At Sir Ganga Ram Hospital, Chowbey established  Minimal Access, Metabolic and Bariatric Surgery Centre  where the team led by him is reported to have performed over 55,000  minimally invasive procedures . [ 7 ]  His list of patients included  K. R. Narayanan , former President of India,  Dalai Lama  and  Arun Jaitley [ 8 ]  who were operated on by him in 2001, 2008 and 2014 respectively. He has been involved in the designing of the  International Centre of Excellence for Bariatric Surgery Program  of the Surgical Review Corporation, USA [ 9 ]  and was one of the key members among the founders of the Asia Pacific Hernia Society where he served as the founder president. [ 10 ]  He is the president of the Asia Pacific Metabolic and Bariatric Surgery Society, Asia Pacific Chapter of International Federation for the Surgery of Obesity and Metabolic Disorders, and International Federation for the Surgery of Obesity and Metabolic Disorders and has served Obesity and Metabolic Surgery Society of India and the Indian Association of Gastrointestinal Endo-Surgeons as their president. He sits in the Board of Governors of the Gasless Laparoscopic and Endoscopic Surgeons Society International and is the Advisor to the Asia Pacific Endosurgery Task Force (AETF). [ 7 ]


Chowbey is a founding designee in the International Centre of Excellence for Bariatric Surgery Program by Surgical Review Corporation, USA. [ 11 ]  He is an Honorary Fellow of the American Society of Metabolic and Bariatric Surgery, [ 12 ]  International Medical Science Academy (IMSA), International Congress of Surgeons (ICS) and Association of Surgeons of India (ASI). [ 6 ]  He is also an Honorary Member of the Japanese Society of Endoscopic Surgeons, [ 13 ]  German Hernia Society, Indonesian Hernia Society and Gulf Cooperation Council Hernia Society (National Chapter of Asia Pacific Hernia Society, Dubai). [ 7 ]  He was included in the  Guinness Book of World Records  in 1997 and the  Limca Book of Records  for more than 80,000 major minimal access surgeries (1992-2018) performed by a surgeon. [ 14 ]  Dr Chowbey also has a Limca Book of Record for establishing the first dedicated Department of Minimal Access Surgery (MAS ) in the Asian subcontinent in 1995 [ 15 ] [ 9 ]  The Government of India awarded him the civilian honour of the  Padma Shri  in 2002. [ 5 ]


Chowbey was the first to introduce the technique called MAFT (Minimally Invasive Fistula Treatment) in entire Asia-Pacific region. The technique is performed for surgical treatment of anal fistulas through a fistulascope. This concept was a breakthrough surgical treatment for anal fistulas as it has a very short recovery period, requires no dressings and there are no chances of loss of control (fecal incontinence). [ 16 ] [ 17 ]


He operated on 14 years old Mihir Jain, believed to be World's heaviest teenager weighing 237 Kilograms in July 2018. [ 18 ]  By December 2018, Mihir's weight reduced by 100 Kg and now stands at 137 kg. [ 19 ]


In 2021, Dr Chowbey embarked on unleashing the excellence of next generation robot, Versius to extend the benefits of robotic surgery even in common surgical conditions like Gallbladder surgery, hernia etc.This next-generation robotic surgery is designed to provide all benefits of laparoscopic surgery with added precision, accuracy and safety. [ 20 ]


A  gastric balloon , also known as an  intragastric balloon  ( IGB ) or a  stomach balloon , is an inflatable  medical device  that is temporarily placed into the  stomach  to help  reduce weight . It is designed to help provide weight loss when diet and exercise have failed and surgery is not wanted by or recommended for the patient.


Intragastric balloons are an alternative to  bariatric surgery  (or weight loss surgery), which is not generally offered to patients with a  body mass index  of less than 35. Gastric balloons are also designed for patients who require weight-loss support but who do not want to commit to surgical interventions. [ 1 ]


Intragastric balloons help induce weight loss by increasing satiety, delaying gastric emptying, and reducing the amount of food eaten at each meal. [ 1 ]  Gastric balloons take up space in the stomach, which limits the amount of food that can be held. This creates an early feeling of fullness and satiety. A reduced intake of food then results in weight loss.


Most balloons require  endoscopy  for removal or placement. They are usually placed for up to six months, though some devices are placed for twelve months. The device is then removed, again using endoscopy. Longer placement is not advised because of the danger of damage to the tissue wall and degradation of the balloon. The use of the balloon is complemented with counseling and nutritional support or advice.


Endoscopic placement of the balloon is temporary and reversible without surgical incisions. The gastric balloon for weight loss differs from the  Sengstaken-Blakemore  balloon used to stop esophageal and gastric bleeding.


Gastric balloon uptake has until recently been limited due to the need for endoscopy for placement or removal. [ 2 ]


Procedureless, or non-endoscopic, intragastric balloons offer a promising alternative to historic endoscopic balloons. Non-endoscopic balloons are also a less invasive alternative to weight-loss surgery. [ 2 ]


In 2015, Allurion's Elipse gastric balloon became the world's first non-endoscopic swallowable gastric balloon when it gained approval in Europe. [ 3 ] [ 4 ]  Except under exceptional circumstances, it does not require endoscopy or surgery for placement or removal. [ 2 ]  The non-endoscopic gastric balloon capsule is swallowed for placement and once in the stomach is filled with saline liquid. After 16 weeks, the non-endoscopic gastric balloon then automatically deflates and passes naturally at the end of placement. A recent meta analysis of 6 studies found the balloon was a safe device offering effective weight loss. Total pooled weight loss at the completion of treatment (4–6 months) was 12.8% and at 12 months was 10.9%. [ 4 ]


Adjustable gastric balloons are able to increase or decrease their volume. While non-adjustable gastric balloons have been successfully used for weight loss for the last 30 years, the adjustability function was developed to address the following issues: (1) variability of response and reduced efficacy after 3 months  [ 5 ] [ 6 ] [ 7 ]  and (2) intolerance necessitating early balloon extraction. [ 8 ] [ 9 ]  Alleviating intolerance with a downward adjustment and renewing weight loss after balloon upward adjustment, are responsible for higher success rates compared with non-adjustable balloons. [ 10 ] [ 11 ]  The Spatz3 adjustable gastric balloon is the first intragastric balloon approved for 1-year implantation (outside of the US), while featuring an adjustability function that provides balloon volume changes as needed.


The device is intended to be used by people with a  body mass index  of more than 27 kg/m 2 . [ 12 ]  or between 30 and 40 kg/m 2 [ 13 ]  and have weight-related co-morbidity. It should not be applied to patients with certain intestinal problems such as inflammatory bowel disease or delayed gastric emptying, who are pregnant, or who are taking blood thinner medications such as Coumadin. Low dose aspirin (100 mg) is permitted. [ 13 ]


A 2016 meta analysis of studies showed short term weight loss without any mortality. [ 14 ]  It was calculated that the weight loss was 1.59 and 1.34 kg/m 2  for overall and 3-month  body mass index  (BMI) loss, respectively, and 4.6 and 4.77 kg for overall and 3-month weight loss, respectively. [ 14 ]


Results are influenced by the adherence to nutritional and dietary programs. Long-term studies show promise for patients who combine balloon treatment with exercise and a healthy diet. In a study on the 'Long-Term Efficacy of the Elipse Gastric Balloon System: An International Multicenter Study, Dr. Roberta Ienca and colleagues' report on 509 patients who received the non-endoscopic Elipse balloon and were followed for one year. After 4 months of treatment, patients achieved weight loss of 14.4 kg or 13.9% of total body weight. At one-year follow-up, 95% of this weight loss was maintained by patients included in the study. [ 2 ]


Gastric balloons are generally considered to be safe and effective in the short term. [ 15 ]  Existing clinical data shows an acceptable safety profile. One of the largest intragastric balloon studies ever performed, which included 1770 patients, demonstrated an excellent safety profile. [ 2 ]


There can be procedure-related side effects due to endoscopy and anesthesia on balloons that require medical intervention for placement or removal. [ 13 ]  On very rare occasions, the endoscopic placement of a balloon has led to death. [ 16 ] [ 17 ]


Several studies have demonstrated that the data on both the efficacy and safety for the non-endoscopic Allurion Elipse gastric balloon compares favorably with balloons that require endoscopy. [ 2 ]  It showed an acceptable safety profile with 0.2% of serious adverse events, which is comparable to the Orbera balloon, which requires endoscopy. [ 4 ]


Post-placement side effects of gastric balloons are common and may include nausea, vomiting, reflux and stomach cramps. [ 18 ]  Other side effects include indigestion, bloating, flatulence and diarrhea. [ 14 ]  Rare side effects include esophagitis, gastric ulcer formation or gastric perforation. [ 19 ]  The device can become deflated and slip into the lower intestines. Migration of a balloon can lead to  bowel obstruction . [ 19 ]


Currently, there are three types of  FDA -approved gastric balloons in the USA. These approved devices are placed via the esophagus using endoscopy. This can be done in an  outpatient setting  under sedation. One further balloon, Allurion's Ellipse, has European  CE  approval and does not require endoscopy for placement or removal. [ 1 ] [ 4 ]


Once in place the balloon is filled with saline and remains as a free-floating object in the stomach cavity, too big to pass through the  pylorus . In addition to saline, the balloon that is made from silicone may contain some radio-opaque material as a radiographic marker and a dye such as  methylene blue  to alert the patient if the balloon leaks. [ 15 ]  Studies have suggested that fluid is superior to air for distending gastric balloons. [ 14 ]  Inflated balloons reduce the operative volume capacity of the stomach. While the typical gastric volume is about 900 ml, an inflated balloon may take up most of the space, about 700 (+/-100) ml.


Gastric balloon-type devices have been approved in many countries, among them Australia, Canada, Mexico, India, Guatemala and several European and South American countries. [ 20 ]  They became available in the United States in 2015 when two different balloon devices were approved by the FDA. [ 21 ] [ 13 ]


Costs for the gastric balloon are surgeon-specific and vary by region. Average cost in the US is US$8,150, and generally less in other countries. Average cost in Europe is around €3,000. Insurance coverage is usually not provided in the US. [ 24 ]  There are three cost categories for the intragastric balloon: pre-operative (e.g. professional fees, lab work and testing), the procedure itself (e.g. surgeon, surgical assistant, anesthesia and hospital fees) and post-operative (e.g. follow-up physician office visits, vitamins and supplements).


The first person to use a gastric balloon for the treatment of obesity was A. Henning 1979. (Inn. Med.6(1979),149) He and his wife used it in a self-experiment.


The use of gastric filling devices to induce weight loss is not new.  DeBakey's  review in 1938 showed that  bezoars  led to weight loss. [ 25 ]  Free floating intragastric balloons were used by Nieben and Harboe in 1982. [ 26 ]  Percival presented a “balloon diet” in 1984 when he placed inflated mammary implants as gastric balloons. [ 27 ]   Elipse mide Balonu   In 1985 the Garren-Edwards Bubble was introduced as the first FDA-approved device, but the approval was withdrawn seven years later because of complications. [ 28 ]  Analysis of its problems led to recommendations for safer designs. [ 12 ]  While a number of further developed devices were used outside of the US, mostly in Europe and South America, the FDA did not approve any new devices until 2015. [ 28 ]  In October 2017, ReShape Medical, which makes gastric balloons, was acquired by EnteroMedics in $38m cash-and-stock deal. [ 29 ] [ 30 ]


Gelesis100 , sold under the brand name  Plenity , is an oral  hydrogel  used to treat  overweight  and  obesity . [ 1 ]  It absorbs water and expands in the  stomach  and  small bowel  thereby increasing feelings of fullness. Possible side effects include primarily gastrointestinal symptoms, [ 2 ]  such as  diarrhea ,  abdominal distention , infrequent bowel movements,  constipation ,  abdominal pain , and  flatulence . [ 3 ]  It is contraindicated in  pregnancy ,  chronic malabsorption syndromes , and  cholestasis . [ 1 ]  The  US Food and Drug Administration  approved it in 2019 as a medical device. Gelesis100 was developed by the company  Gelesis .


The US Food and Drug Administration approved the use of Gelesis100 in April 2019 as a  medical device . [ 4 ]  Gelesis100 is the first treatment of its kind for overweight and obesity. [ 2 ]  In 2022, the American Gastroenterology Association published a guideline for the management of obesity, which recommended the use of Gelesis100 be limited to clinical trials due to limited evidence. [ 5 ]


Gelesis100 is used to treat obesity and overweight as an  anti-obesity medication . [ 1 ]  Gelesis100 is taken as a pill before meals with water. [ 6 ] [ 7 ]


Gelesis100 has been criticized for its small impact on weight loss relative to side effects. [ 8 ]


Gelesis100 is an oral superabsorbent hydrogel, which is produced from  carboxymethylcellulose  and  citric acid . [ 1 ] [ 9 ]  The cross-linked product forms a hydrophilic matrix, which absorbs water. [ 1 ]  Taken in capsule form by mouth, [ 10 ]  as Gelesis100 absorbs water, it expands in the stomach and small intestine. [ 3 ] [ 6 ]  After absorbing water, a semisolid gel structure forms, which may promote satiety and result in weight loss [ 1 ]  via reduced caloric intake. [ 5 ]


Gelesis100 is contraindicated in pregnancy, chronic malabsorption syndromes, and cholestasis. [ 1 ]


Side effects consist of minor gastrointestinal symptoms, [ 2 ]  including diarrhea, abdominal distention, infrequent bowel movements, constipation, abdominal pain, and flatulence. [ 3 ]  Gelesis100 is not associated with any severe adverse events. [ 11 ]  However, long-term safety data beyond 24 weeks is not available. [ 11 ]


Younan Nowzaradan  ( Persian :  یونان نوزرادان ; born October 11, 1944), [ 1 ]  also known as  Dr. Now , is an Iranian-born American doctor of  Assyrian  heritage, TV personality, and author. He specializes in  vascular surgery  and  bariatric surgery . He is known for helping  morbidly obese  people lose weight on  My 600-lb Life  (2012–present). [ 2 ] [ 3 ]


Nowzaradan was born and raised in  Tehran , Iran, and is of Assyrian heritage. In 1970, he graduated from the  University of Tehran  with a  Doctor of Medicine  degree. [ 4 ]  He then moved to the  United States . He participated in the Medical Orientation Program at  Saint Louis University  in 1971 and completed a Rotating Surgical Internship at St. John Hospital (operated by  St. John Providence Health System ) in  Detroit ,  Michigan . [ 4 ]  Nowzaradan is a fellow of the  American College of Surgeons .


Nowzaradan is currently affiliated with Houston Obesity Surgery in  Houston, TX , and practices at several local hospitals. [ 4 ]   He is  the author of several scholarly publications on  obesity  and  laparoscopy . [ 5 ]


He has been on  My 600-lb Life  since 2012. [ 6 ]  He has also appeared on installments of  Body Shock , including the episodes "Half Ton Dad", "Half Ton Teen", and "Half Ton Mum". [ 6 ]  He also published two books titled  Last Chance to Live  (2017) and  The Scale Does Not Lie, People Do  (2019). [ 7 ]  Dr. Now made several appearances at Texas theme parks such as Six Flags  AstroWorld  to promote health awareness in the early 2000s, reaching out to youth and encouraging them to make good dietary choices.


He was married to Delores McRedmond for 31 years; they divorced in 2004. The couple had three children together. [ 8 ]  His son, Jonathan Nowzaradan (b. 1978), works as a director and producer for  My 600-lb Life . [ 9 ] [ 10 ]


Obesity  is a medical condition, sometimes considered a  disease , [ 8 ] [ 9 ] [ 10 ]  in which excess  body fat  has accumulated to such an extent that it can potentially have negative effects on  health . People are classified as obese when their  body mass index  (BMI)—a person's weight divided by the square of the person's height—is over  30  kg / m 2 ; the range  25–30  kg / m 2  is defined as  overweight . [ 1 ]  Some  East Asian  countries use lower values to calculate obesity. [ 11 ]  Obesity is a major cause of disability and is  correlated with various diseases and conditions , particularly  cardiovascular diseases ,  type 2 diabetes ,  obstructive sleep apnea , certain types of  cancer , and  osteoarthritis . [ 2 ] [ 12 ] [ 13 ]


Obesity has individual, socioeconomic, and environmental causes. Some known causes are  diet , physical activity,  automation ,  urbanization ,  genetic susceptibility ,  medications ,  mental disorders ,  economic policies ,  endocrine disorders , and exposure to  endocrine-disrupting chemicals . [ 1 ] [ 4 ] [ 14 ] [ 15 ]


While a many people living with obesity attempt to lose weight and are often successful, maintaining weight loss long-term is rare. [ 16 ]  Obesity prevention requires a complex approach, including interventions at medical, societal, community, family, and individual levels. [ 1 ] [ 13 ]  Changes to  diet  as well as  exercising  are the main treatments recommended by health professionals. [ 2 ]  Diet quality can be improved by reducing the consumption of energy-dense foods, such as those high in fat or sugars, and by increasing the intake of  dietary fiber , although the  World Health Organization  stresses that these improvements are a societal responsibility and that these dietary choices should be made the most available, affordable, and accessible options. [ 1 ]   Medications  can be used, along with a suitable diet, to reduce appetite or decrease fat absorption. [ 5 ]  If diet, exercise, and medication are not effective, a  gastric balloon  or  surgery  may be performed to reduce stomach volume or length of the intestines, leading to feeling full earlier, or a reduced ability to absorb nutrients from food. Many do not realize that metabolic surgery is not only about reducing intake, it has also been shown to alter gut hormones for a period of time.  [ 6 ] [ 17 ]


Obesity is a leading  preventable cause of death  worldwide, with increasing rates in adults and  children . [ 18 ]  In 2022, over 1 billion people lived with obesity worldwide (879 million adults and 159 million children), representing more than a double of adult cases (and four times higher than cases among children) registered in 1990. [ 7 ] [ 19 ]  Obesity is more common in women than in men. [ 1 ]  Today, obesity is  stigmatized  in most of the world. Conversely, some cultures, past and present, have a favorable view of obesity, seeing it as a symbol of wealth and fertility. [ 2 ] [ 20 ]  The  World Health Organization , the US, Canada, Japan, Portugal, Germany, the  European Parliament  and medical societies, e.g. the  American Medical Association , classify obesity as a disease. Others, such as the  UK , do not. [ 21 ] [ 22 ] [ 23 ] [ 24 ]


Obesity is typically defined as a substantial accumulation of  body fat  that could impact health. [ 26 ]  Medical organizations tend to classify people living with obesity as based on  body mass index  (BMI) – a ratio of a person's weight in  kilograms  to the  square  of their height in  meters . For adults, the  World Health Organization  (WHO) defines " overweight " as a BMI 25 or higher, and "obesity" as a BMI 30 or higher. [ 26 ]  The U.S.  Centers for Disease Control and Prevention  (CDC) further subdivides obesity based on BMI, with a BMI 30 to 35 called class 1 obesity; 35 to 40, class 2 obesity; and 40+, class 3 obesity. [ 27 ]


For children, obesity measures take age into consideration along with height and weight. For children aged 5–19, the WHO defines obesity as a BMI two  standard deviations  above the  median  for their age (a BMI around 18 for a five-year old; around 30 for a 19-year old). [ 26 ] [ 28 ]  For children under five, the WHO defines obesity as a weight three standard deviations above the median for their height. [ 26 ]


Some modifications to the WHO definitions have been made by particular organizations. [ 29 ]  The surgical literature breaks down class II and III or only class III obesity into further categories whose exact values are still disputed. [ 30 ]


As Asian populations develop negative health consequences at a lower BMI than  Caucasians , some nations have redefined obesity; Japan has defined obesity as any BMI greater than 25 kg/m 2 [ 11 ]  while China uses a BMI of greater than 28 kg/m 2 . [ 29 ]


The preferred obesity metric in scholarly circles is the  body fat percentage  (BF%) – the ratio of the total weight of person's fat to his or her body weight, and BMI is viewed merely as a way to approximate BF%. [ 31 ]  According to  American Society of Bariatric Physicians , levels in excess of 32% for women and 25% for men are generally considered to indicate obesity. [ 32 ]


BMI is now viewed as outdated in numerous countries. It ignores variations between individuals in amounts of lean body mass, particularly  muscle  mass. Individuals involved in heavy physical labor or sports may have high BMI values despite having little fat. For example, more than half of all  NFL  players are classified as "obese" (BMI ≥ 30), and 1 in 4 are classified as "extremely obese" (BMI ≥ 35), according to the BMI metric. [ 33 ]  However, their mean  body fat percentage , 14%, is well within what is considered a healthy range. [ 34 ]  Similarly,  Sumo  wrestlers may be categorized by BMI as "severely obese" or "very severely obese" but many Sumo wrestlers are not categorized as obese when body fat percentage is used instead (having <25% body fat). [ 35 ]  Some Sumo wrestlers were found to have no more body fat than a non-Sumo comparison group, with high BMI values resulting from their high amounts of lean body mass. [ 35 ]


Canada utilises BMI sparingly within their method of defining levels of obesity through use of the Edmonton Scale (for adult obesity). This scale also introduces factors such as Quality of Life, Mental Health & Mobility amongst others. In recent years, Canada chose to allow both Chilli & Ireland to adapt their obesity guidelines to suit both countries' health systems. In Ireland, obesity is now defined as "a Complex, Chronic & Relapsing Disease".


Obesity increases a person's risk of developing various metabolic diseases,  cardiovascular disease ,  osteoarthritis ,  Alzheimer disease ,  depression , and certain types of cancer. [ 36 ]  Depending on the degree of obesity and the presence of comorbid disorders, obesity is associated with an estimated 2–20 year shorter life expectancy. [ 37 ] [ 36 ]  High BMI is a marker of risk for, but not a direct cause of, diseases caused by diet and physical activity. [ 13 ]


Obesity is one of the leading  preventable causes of death  worldwide. [ 38 ] [ 39 ] [ 40 ]  The mortality risk is lowest at a BMI of 20–25 kg/m 2 [ 41 ] [ 37 ] [ 42 ]  in non-smokers and at 24–27 kg/m 2  in current smokers, with risk increasing along with changes in either direction. [ 43 ] [ 44 ]  This appears to apply in at least four continents. [ 42 ]  Other research suggests that the association of BMI and waist circumference with mortality is U- or J-shaped, while the association between  waist-to-hip ratio  and  waist-to-height ratio  with mortality is more positive. [ 45 ]  In Asians the risk of negative health effects begins to increase between 22 and 25 kg/m 2 . [ 46 ]  In 2021, the  World Health Organization  estimated that obesity caused at least 2.8 million deaths annually. [ 47 ]  On average, obesity reduces life expectancy by six to seven years, [ 2 ] [ 48 ]  a BMI of 30–35 kg/m 2  reduces life expectancy by two to four years, [ 37 ]  while severe obesity (BMI ≥ 40 kg/m 2 ) reduces life expectancy by ten years. [ 37 ]


Obesity increases the risk of many physical and mental conditions. These comorbidities are most commonly shown in  metabolic syndrome , [ 2 ]  a combination of medical disorders which includes:  diabetes mellitus type 2 ,  high blood pressure ,  high blood cholesterol , and  high triglyceride levels . [ 49 ]  A study from the  RAK Hospital  found that obese people are at a greater risk of developing  long COVID . [ 50 ]  The CDC has found that obesity is the single strongest risk factor for severe COVID-19 illness. [ 51 ]


Complications are either directly caused by obesity or indirectly related through mechanisms sharing a common cause such as a poor diet or a  sedentary lifestyle . The strength of the link between obesity and specific conditions varies. One of the strongest is the link with  type 2 diabetes . Excess body fat underlies 64% of cases of diabetes in men and 77% of cases in women. [ 52 ] : 9


Health consequences fall into two broad categories: those attributable to the effects of increased fat mass (such as  osteoarthritis ,  obstructive sleep apnea , social stigmatization) and those due to the increased number of  fat cells  ( diabetes ,  cancer ,  cardiovascular disease ,  non-alcoholic fatty liver disease ). [ 2 ] [ 53 ]  Increases in body fat alter the body's response to insulin, potentially leading to  insulin resistance . Increased fat also creates a  proinflammatory state , [ 54 ] [ 55 ]  and a  prothrombotic  state. [ 53 ] [ 56 ]


Newer research has focused on methods of identifying healthier obese people by clinicians, and not treating obese people as a monolithic group. [ 81 ]  Obese people who do not experience medical complications from their obesity are sometimes called  (metabolically) healthy obese , but the extent to which this group exists (especially among older people) is in dispute. [ 82 ]  The number of people considered  metabolically healthy  depends on the definition used, and there is no universally accepted definition. [ 83 ]  There are numerous obese people who have relatively few metabolic abnormalities, and a minority of obese people have no medical complications. [ 83 ]  The guidelines of the  American Association of Clinical Endocrinologists  call for physicians to use  risk stratification  with obese patients when considering how to assess their risk of developing type 2 diabetes. [ 84 ] : 59–60


In 2014, the BioSHaRE– EU  Healthy Obese Project (sponsored by Maelstrom Research, a team under the  Research Institute of the McGill University Health Centre ) came up with two definitions for  healthy obesity , one more strict and one less so: [ 82 ] [ 85 ]


To come up with these criteria, BioSHaRE controlled for age and tobacco use, researching how both may effect the metabolic syndrome associated with obesity, but not found to exist in the metabolically healthy obese. [ 86 ]  Other definitions of metabolically healthy obesity exist, including ones based on waist circumference rather than BMI, which is unreliable in certain individuals. [ 83 ]


Another identification metric for health in obese people is  calf   strength , which is positively correlated with  physical fitness  in obese people. [ 87 ]   Body composition  in general is hypothesized to help explain the existence of metabolically healthy obesity—the metabolically healthy obese are often found to have low amounts of  ectopic  fat (fat stored in tissues other than adipose tissue) despite having overall fat mass equivalent in weight to obese people with  metabolic syndrome . [ 88 ] : 1282


Although the negative health consequences of obesity in the general population are well supported by the available research evidence, health outcomes in certain subgroups seem to be improved at an increased BMI, a phenomenon known as the obesity survival paradox. [ 89 ]  The paradox was first described in 1999 in overweight and obese people undergoing  hemodialysis [ 89 ]  and has subsequently been found in those with  heart failure  and  peripheral artery disease  (PAD). [ 90 ]


In people with heart failure, those with a BMI between 30.0 and 34.9 had lower mortality than those with a normal weight. This has been attributed to the fact that people often lose weight as they become progressively more ill. [ 91 ]  Similar findings have been made in other types of heart disease. People with class I obesity and heart disease do not have greater rates of further heart problems than people of normal weight who also have heart disease. In people with greater degrees of obesity, however, the risk of further cardiovascular events is increased. [ 92 ] [ 93 ]  Even after  cardiac bypass surgery , no increase in mortality is seen in the overweight and obese. [ 94 ]  One study found that the improved survival could be explained by the more aggressive treatment obese people receive after a cardiac event. [ 95 ]  Another study found that if one takes into account  chronic obstructive pulmonary disease  (COPD) in those with PAD, the benefit of obesity no longer exists. [ 90 ]


The " a calorie is a calorie " model of obesity posits a combination of excessive  food energy  intake and a lack of  physical activity  as the cause of most cases of obesity. [ 96 ]  A limited number of cases are due primarily to genetics, medical reasons, or psychiatric illness. [ 15 ]  The  satiety value  shows that the feeling of  satiety  per  calorie  varies between food types. [ 97 ]  Increasing rates of obesity at a societal level are felt to be due to an easily accessible and palatable  diet , [ 98 ]  increased  reliance on cars , and mechanized manufacturing. [ 99 ] [ 100 ]


Some other factors have been proposed as causes towards rising rates of obesity worldwide, including  insufficient sleep ,  endocrine disruptors , increased usage of certain medications (such as  atypical antipsychotics ), [ 101 ]  increases in ambient temperature, decreased rates of  smoking , [ 102 ]  demographic changes, increasing maternal age of first-time mothers, changes to  epigenetic  dysregulation from the environment, increased phenotypic variance via  assortative mating , social pressure to  diet , [ 103 ]  among others. According to one study, factors like these may play as big of a role as excessive food energy intake and a lack of physical activity; [ 104 ]  however, the relative magnitudes of the effects of any proposed cause of obesity is varied and uncertain, as there is a general need for randomized controlled trials on humans before definitive statement can be made. [ 105 ]


According to the  Endocrine Society , there is "growing evidence suggesting that obesity is a disorder of the  energy homeostasis  system, rather than simply arising from the passive accumulation of excess weight". [ 106 ]


Excess appetite for palatable, high-calorie food (especially fat, sugar, and certain animal proteins) is seen as the primary factor driving obesity worldwide, likely because of imbalances in  neurotransmitters  affecting the drive to eat. [ 108 ]   Dietary energy supply  per capita varies markedly between different regions and countries. It has also changed significantly over time. [ 107 ]  From the early 1970s to the late 1990s the average  food energy  available per person per day (the amount of food bought) increased in all parts of the world except Eastern Europe. The United States had the highest availability with 3,654 calories (15,290 kJ) per person in 1996. [ 107 ]  This increased further in 2003 to 3,754 calories (15,710 kJ). [ 107 ]  During the late 1990s, Europeans had 3,394 calories (14,200 kJ) per person, in the developing areas of Asia there were 2,648 calories (11,080 kJ) per person, and in sub-Saharan Africa people had 2,176 calories (9,100 kJ) per person. [ 107 ] [ 109 ]  Total food energy consumption has been found to be related to obesity. [ 110 ]


The widespread availability of  dietary guidelines [ 111 ]  has done little to address the problems of overeating and poor dietary choice. [ 112 ]  From 1971 to 2000, obesity rates in the United States increased from 14.5% to 30.9%. [ 113 ]  During the same period, an increase occurred in the average amount of food energy consumed. For women, the average increase was 335 calories (1,400 kJ) per day (1,542 calories (6,450 kJ) in 1971 and 1,877 calories (7,850 kJ) in 2004), while for men the average increase was 168 calories (700 kJ) per day (2,450 calories (10,300 kJ) in 1971 and 2,618 calories (10,950 kJ) in 2004). Most of this extra food energy came from an increase in carbohydrate consumption rather than fat consumption. [ 114 ]  The primary sources of these extra carbohydrates are sweetened beverages, which now account for almost 25 percent of daily food energy in young adults in America, [ 115 ]  and potato chips. [ 116 ]  Consumption of  sweetened beverages  such as soft drinks, fruit drinks, and iced tea is believed to be contributing to the rising rates of obesity [ 117 ] [ 118 ]  and to an increased risk of  metabolic syndrome  and  type 2 diabetes . [ 119 ]   Vitamin D deficiency  is related to diseases associated with obesity. [ 120 ]


As societies become increasingly reliant on  energy-dense , big-portions, and  fast-food  meals, the association between fast-food consumption and obesity becomes more concerning. [ 121 ]  In the United States, consumption of fast-food meals tripled and food energy intake from these meals quadrupled between 1977 and 1995. [ 122 ]


Agricultural policy  and  techniques  in the United States and Europe have led to lower  food prices . In the United States, subsidization of corn, soy, wheat, and rice through the  U.S. farm bill  has made the main sources of processed food cheap compared to fruits and vegetables. [ 123 ]   Calorie count laws  and  nutrition facts labels  attempt to steer people toward making healthier food choices, including awareness of how much food energy is being consumed.


Obese people consistently under-report their food consumption as compared to people of normal weight. [ 124 ]  This is supported both by tests of people carried out in a  calorimeter  room [ 125 ]  and by direct observation.


A sedentary lifestyle may play a significant role in obesity. [ 52 ] : 10   Worldwide there has been a large shift towards less physically demanding work, [ 126 ] [ 127 ] [ 128 ]  and currently at least 30% of the world's population gets insufficient exercise. [ 127 ]  This is primarily due to increasing use of mechanized transportation and a greater prevalence of labor-saving technology in the home. [ 126 ] [ 127 ] [ 128 ]  In children, there appear to be declines in levels of physical activity (with particularly strong declines in the amount of walking and physical education), likely due to safety concerns, changes in social interaction (such as fewer relationships with neighborhood children), and inadequate urban design (such as too few public spaces for safe physical activity). [ 129 ]  World trends in active leisure time  physical activity  are less clear. The World Health Organization indicates people worldwide are taking up less active recreational pursuits, while research from Finland [ 130 ]  found an increase and research from the United States found leisure-time physical activity has not changed significantly. [ 131 ]  Physical activity in children may not be a significant contributor. [ 132 ]


In both children and adults, there is an association between television viewing time and the risk of obesity. [ 133 ] [ 134 ] [ 135 ]  Increased media exposure increases the rate of childhood obesity, with rates increasing proportionally to time spent watching television. [ 136 ]


Like many other medical conditions, obesity is the result of an interplay between genetic and environmental factors. [ 138 ]   Polymorphisms  in various  genes  controlling  appetite  and  metabolism  predispose to obesity when sufficient food energy is present. As of 2006, more than 41 of these sites on the human genome have been linked to the development of obesity when a favorable environment is present. [ 139 ]  People with two copies of the  FTO gene  (fat mass and obesity associated gene) have been found on average to weigh 3–4 kg more and have a 1.67-fold greater risk of obesity compared with those without the risk  allele . [ 140 ]  The differences in BMI between people that are  due to genetics  varies depending on the population examined from 6% to 85%. [ 141 ]


Obesity is a major feature in several syndromes, such as  Prader–Willi syndrome ,  Bardet–Biedl syndrome ,  Cohen syndrome , and  MOMO syndrome . (The term "non-syndromic obesity" is sometimes used to exclude these conditions.) [ 142 ]  In people with early-onset severe obesity (defined by an onset before 10 years of age and body mass index over three  standard deviations  above normal), 7% harbor a single point DNA mutation. [ 143 ]


Studies that have focused on inheritance patterns rather than on specific genes have found that 80% of the offspring of two  obese parents  were also obese, in contrast to less than 10% of the offspring of two parents who were of normal weight. [ 144 ]  Different people exposed to the same environment have different risks of obesity due to their underlying genetics. [ 145 ]


The  thrifty gene hypothesis  postulates that, due to dietary scarcity during human evolution, people are prone to obesity. Their ability to take advantage of rare periods of abundance by storing energy as fat would be advantageous during times of varying food availability, and individuals with greater adipose reserves would be more likely to survive  famine . This tendency to store fat, however, would be maladaptive in societies with stable food supplies. [ medical citation needed ]  This theory has received various criticisms, and other evolutionarily-based theories such as the  drifty gene hypothesis  and the  thrifty phenotype hypothesis  have also been proposed. [ medical citation needed ]


Certain physical and mental illnesses and the pharmaceutical substances used to treat them can increase risk of obesity. Medical illnesses that increase obesity risk include several rare genetic syndromes (listed above) as well as some congenital or acquired conditions:  hypothyroidism ,  Cushing's syndrome ,  growth hormone deficiency , [ 146 ]  and some  eating disorders  such as  binge eating disorder  and  night eating syndrome . [ 2 ]  However, obesity is not regarded as a psychiatric disorder, and therefore is not listed in the  DSM-IVR  as a psychiatric illness. [ 147 ]  The risk of overweight and obesity is higher in patients with psychiatric disorders than in persons without psychiatric disorders. [ 148 ]  Obesity and  depression  influence each other mutually, with obesity increasing the risk of clinical depression, and also depression leading to a higher chance of developing obesity. [ 3 ]


Certain medications may cause weight gain or changes in  body composition ; these include  insulin ,  sulfonylureas ,  thiazolidinediones ,  atypical antipsychotics ,  antidepressants ,  steroids , certain  anticonvulsants  ( phenytoin  and  valproate ),  pizotifen , and some forms of  hormonal contraception . [ 2 ]


While genetic influences are important to understanding obesity, they cannot completely explain the dramatic increase seen within specific countries or globally. [ 149 ] [ better source needed ]  Though it is accepted that energy consumption in excess of energy expenditure leads to increases in body weight on an individual basis, the cause of the shifts in these two factors on the societal scale is much debated. There are a number of theories as to the cause but most believe it is a combination of various factors.


The correlation between  social class  and BMI varies globally. Research in 1989 found that in developed countries women of a high social class were less likely to be obese. No significant differences were seen among men of different social classes. In the developing world, women, men, and children from high social classes had greater rates of obesity. [ better source needed ] [ 150 ]  In 2007 repeating the same research found the same relationships, but they were weaker. The decrease in strength of correlation was felt to be due to the effects of  globalization . [ 151 ]  Among developed countries, levels of adult obesity, and percentage of teenage children who are overweight, are correlated with  income inequality . A similar relationship is seen among US states: more adults, even in higher social classes, are obese in more unequal states. [ 152 ]


Many explanations have been put forth for associations between BMI and social class. It is thought that in developed countries, the wealthy are able to afford more nutritious food, they are under greater social pressure to remain slim, and have more opportunities along with greater expectations for  physical fitness . In  undeveloped countries  the ability to afford food, high energy expenditure with physical labor, and cultural values favoring a larger body size are believed to contribute to the observed patterns. [ 151 ]  Attitudes toward body weight held by people in one's life may also play a role in obesity. A correlation in BMI changes over time has been found among friends, siblings, and spouses. [ 153 ]  Stress and perceived low social status appear to increase risk of obesity. [ 152 ] [ 154 ] [ 155 ]


Smoking has a significant effect on an individual's weight. Those who quit smoking gain an average of 4.4 kilograms (9.7 lb) for men and 5.0 kilograms (11.0 lb) for women over ten years. [ 156 ]  However, changing rates of smoking have had little effect on the overall rates of obesity. [ 157 ]


In the United States, the number of children a person has is related to their risk of obesity. A woman's risk increases by 7% per child, while a man's risk increases by 4% per child. [ 158 ]  This could be partly explained by the fact that having dependent children decreases physical activity in Western parents. [ 159 ]


In the developing world urbanization is playing a role in increasing rate of obesity. In China overall rates of obesity are below 5%; however, in some cities rates of obesity are greater than 20%. [ 160 ]  In part, this may be because of urban design issues (such as inadequate public spaces for physical activity). [ 129 ]  Time spent in motor vehicles, as opposed to  active transportation  options such as cycling or walking, is correlated with increased risk of obesity. [ 161 ] [ 162 ]


Malnutrition  in early life is believed to play a role in the rising rates of obesity in the  developing world . [ 163 ]  Endocrine changes that occur during periods of malnutrition may promote the storage of fat once more food energy becomes available. [ 163 ]


The study of the effect of infectious agents on metabolism is still in its early stages.  Gut flora  has been shown to differ between lean and obese people. There is an indication that gut flora can affect the metabolic potential. This apparent alteration is believed to confer a greater capacity to harvest energy contributing to obesity. Whether these differences are the direct cause or the result of obesity has yet to be determined unequivocally. [ 164 ]  The use of  antibiotics  among children has also been associated with obesity later in life. [ 165 ] [ 166 ]


An association between  viruses  and obesity has been found in humans and several different animal species. The amount that these associations may have contributed to the rising rate of obesity is yet to be determined. [ 167 ]


Not getting enough sleep  is also associated with obesity . [ 168 ] [ 169 ]  Whether one causes the other is unclear. [ 168 ]  Even if short sleep does increase weight gain, it is unclear if this is to a meaningful degree or if increasing sleep would be of benefit. [ 170 ]


Some have proposed that chemical compounds called " obesogens " may play a role in obesity.


Certain aspects of  personality  are associated with being obese. [ 171 ]   Loneliness , [ 172 ]   neuroticism ,  impulsivity , and sensitivity to reward are more common in people who are obese while  conscientiousness  and  self-control  are less common in people who are obese. [ 171 ] [ 173 ]  Because most of the studies on this topic are questionnaire-based, it is possible that these findings overestimate the relationships between personality and obesity: people who are obese might be aware of the  social stigma of obesity  and their questionnaire responses might be biased accordingly. [ 171 ]  Similarly, the personalities of people who are obese as children might be influenced by obesity stigma, rather than these personality factors acting as risk factors for obesity. [ 171 ]


In relation to globalization, it is known that trade liberalization is linked to obesity; research, based on data from 175 countries during 1975–2016, showed that obesity prevalence was positively correlated with trade openness, and the correlation was stronger in developing countries. [ 174 ]


Two distinct but related processes are considered to be involved in the development of obesity: sustained positive energy balance (energy intake exceeding energy expenditure) and the resetting of the body weight "set point" at an increased value. [ 106 ]  The second process explains why finding effective obesity treatments has been difficult. While the underlying biology of this process still remains uncertain, research is beginning to clarify the mechanisms. [ 106 ]


At a biological level, there are many possible  pathophysiological  mechanisms involved in the development and maintenance of obesity. [ 175 ]  This field of research had been almost unapproached until the  leptin  gene was discovered in 1994 by J. M. Friedman's laboratory. [ 176 ]  While leptin and  ghrelin  are produced peripherally, they control appetite through their actions on the  central nervous system . In particular, they and other appetite-related hormones act on the  hypothalamus , a region of the brain central to the regulation of food intake and energy expenditure. There are several circuits within the hypothalamus that contribute to its role in integrating appetite, the  melanocortin  pathway being the most well understood. [ 175 ]  The circuit begins with an area of the hypothalamus, the  arcuate nucleus , that has outputs to the  lateral hypothalamus  (LH) and  ventromedial hypothalamus  (VMH), the brain's feeding and satiety centers, respectively. [ 177 ]


The arcuate nucleus contains two distinct groups of  neurons . [ 175 ]  The first group coexpresses  neuropeptide Y  (NPY) and  agouti-related peptide  (AgRP) and has stimulatory inputs to the LH and inhibitory inputs to the VMH. The second group coexpresses  pro-opiomelanocortin  (POMC) and  cocaine- and amphetamine-regulated transcript  (CART) and has stimulatory inputs to the VMH and inhibitory inputs to the LH. Consequently, NPY/AgRP neurons stimulate feeding and inhibit satiety, while POMC/CART neurons stimulate satiety and inhibit feeding. Both groups of arcuate nucleus neurons are regulated in part by leptin. Leptin inhibits the NPY/AgRP group while stimulating the POMC/CART group. Thus a deficiency in leptin signaling, either via leptin deficiency or leptin resistance, leads to overfeeding and may account for some genetic and acquired forms of obesity. [ 175 ]


The main treatment for obesity consists of  weight loss  via lifestyle interventions, including prescribed  diets  and  physical exercise . [ 22 ] [ 96 ] [ 178 ] [ 179 ]  Although it is unclear what diets might support long-term weight loss, and although the effectiveness of  low-calorie diets  is debated, [ 180 ]  lifestyle changes that reduce calorie consumption or increase physical exercise over the long term also tend to produce some sustained weight loss, despite slow weight regain over time. [ 22 ] [ 180 ] [ 181 ] [ 182 ]


Although 87% of participants in the  National Weight Control Registry  were able to maintain 10% body weight loss for 10 years, [ 183 ] [ clarification needed ]  the most appropriate dietary approach for long term weight loss maintenance is still unknown. [ 184 ]  In the US, intensive behavioral interventions combining both dietary changes and exercise are recommended. [ 22 ] [ 178 ] [ 185 ]   Intermittent fasting  has no additional benefit of weight loss compared to continuous energy restriction. [ 184 ]  Adherence is a more important factor in weight loss success than whatever kind of diet an individual undertakes. [ 184 ] [ 186 ]


Several hypo-caloric diets are effective. [ 22 ]  In the short-term  low carbohydrate diets  appear better than  low fat diets  for weight loss. [ 187 ]  In the long term, however, all types of low-carbohydrate and low-fat diets appear equally beneficial. [ 187 ] [ 188 ]  Heart disease and diabetes risks associated with different diets appear to be similar. [ 189 ]


Promotion of the Mediterranean diets among the obese may lower the risk of heart disease. [ 187 ]  Decreased intake of  sweet drinks  is also related to weight-loss. [ 187 ]  Success rates of long-term weight loss maintenance with lifestyle changes are low, ranging from 2–20%. [ 190 ]  Dietary and lifestyle changes are effective in limiting excessive weight gain in  pregnancy  and improve outcomes for both the mother and the child. [ 191 ]  Intensive behavioral counseling is recommended in those who are both obese and have other risk factors for heart disease. [ 192 ]


Obesity is a complex public health and policy problem because of its prevalence, costs, and health effects. [ 193 ]  As such, managing it requires changes in the wider societal context and effort by communities, local authorities, and governments. [ 185 ]  Public health efforts seek to understand and correct the  environmental factors  responsible for the increasing prevalence of obesity in the population. Solutions look at changing the factors that cause excess food energy consumption and inhibit physical activity. Efforts include federally reimbursed meal programs in schools, limiting direct  junk   food marketing  to children, [ 194 ]  and decreasing access to sugar-sweetened beverages in schools. [ 195 ]  The World Health Organization recommends the taxing of sugary drinks. [ 196 ]  When constructing urban environments, efforts have been made to increase access to parks and to develop pedestrian routes. [ 197 ]


Mass media  campaigns seem to have limited effectiveness in changing behaviors that influence obesity, but may increase knowledge and awareness regarding physical activity and diet, which might lead to changes in the long term. Campaigns might also be able to reduce the amount of time spent  sitting or lying down  and positively affect the intention to be active physically. [ 198 ] [ 199 ]   Nutritional labelling  with energy information on menus might be able to help reducing energy intake while dining in restaurants. [ 200 ]  Some call for policy against  ultra-processed foods . [ 201 ] [ 202 ]


Since the introduction of medicines for the management of obesity in the 1930s, many compounds have been tried. Most of them reduce body weight by small amounts, and several of them are no longer marketed for obesity because of their side effects. Out of 25 anti-obesity medications withdrawn from the market between 1964 and 2009, 23 acted by altering the functions of chemical  neurotransmitters  in the brain. The most common side effects of these drugs that led to withdrawals were mental disturbances, cardiac side effects, and  drug abuse  or  drug dependence . Deaths were reportedly associated with seven products. [ 203 ]


Five medications beneficial for long-term use are:  orlistat ,  lorcaserin ,  liraglutide ,  phentermine–topiramate , and  naltrexone–bupropion . [ 204 ]  They result in weight loss after one year ranged from 3.0 to 6.7 kg (6.6-14.8 lbs) over placebo. [ 204 ]  Orlistat, liraglutide, and naltrexone–bupropion are available in both the United States and Europe, phentermine–topiramate is available only in the United States. [ 205 ]  European regulatory authorities rejected lorcaserin and phentermine-topiramate, in part because of associations of heart valve problems with lorcaserin and more general heart and blood vessel problems with phentermine–topiramate. [ 205 ]  Lorcaserin was available in the United States and then removed from the market in 2020 due to its association with cancer. [ 206 ]  Orlistat use is associated with high rates of gastrointestinal side effects [ 207 ]  and concerns have been raised about negative effects on the kidneys. [ 208 ]  There is no information on how these drugs affect longer-term complications of obesity such as cardiovascular disease or death; [ 5 ]  however, liraglutide, when used for type 2 diabetes, does reduce cardiovascular events. [ 209 ]


In 2019 a  systematic review  compared the effects on weight of various doses of  fluoxetine  (60 mg/d, 40 mg/d, 20 mg/d, 10 mg/d) in obese adults. [ 210 ]  When compared to placebo, all dosages of fluoxetine appeared to contribute to weight loss but lead to increased risk of experiencing side effects such as dizziness, drowsiness, fatigue, insomnia and nausea during period of treatment. However, these conclusions were from low certainty evidence. [ 210 ]  When comparing, in the same review, the effects of fluoxetine on weight of obese adults, to other  anti-obesity agents ,  omega-3  gel and not receiving a treatment, the authors could not reach conclusive results due to poor quality of evidence. [ 210 ]


Among antipsychotic drugs for treating schizophrenia  clozapine  is the most effective, but it also has the highest risk of causing the  metabolic syndrome , of which obesity is the main feature. For people who gain weight because of clozapine, taking  metformin  may reportedly improve three of the five components of the metabolic syndrome: waist circumference, fasting glucose, and fasting triglycerides. [ 211 ]


The most effective treatment for obesity is  bariatric surgery . [ 6 ] [ 22 ]  The types of procedures include  laparoscopic adjustable gastric banding ,  Roux-en-Y gastric bypass ,  vertical-sleeve gastrectomy , and  biliopancreatic diversion . [ 204 ]  Surgery for severe obesity is associated with long-term weight loss, improvement in obesity-related conditions, [ 212 ]  and decreased overall mortality; however, improved metabolic health results from the weight loss, not the surgery. [ 213 ]  One study found a weight loss of between 14% and 25% (depending on the type of procedure performed) at 10 years, and a 29% reduction in all cause mortality when compared to standard weight loss measures. [ 214 ]  Complications occur in about 17% of cases and reoperation is needed in 7% of cases. [ 212 ]


In earlier historical periods obesity was rare and achievable only by a small elite, although already recognised as a problem for health. But as prosperity increased in the  Early Modern period , it affected increasingly larger groups of the population. [ 215 ]  Prior to the 1970s, obesity was a relatively rare condition even in the wealthiest of nations, and when it did exist it tended to occur among the wealthy. Then, a confluence of events started to change the human condition. The average BMI of populations in first-world countries started to increase, and consequently there was a rapid increase in the proportion of people overweight and obese. [ 216 ]


In 1997, the WHO formally recognized obesity as a global epidemic. [ 115 ]  As of 2008, the WHO estimates that at least 500 million adults (greater than 10%) are obese, with higher rates among women than men. [ 217 ]  The global prevalence of obesity more than doubled between 1980 and 2014. In 2014, more than 600 million adults were obese, equal to about 13 percent of the world's adult population, [ 218 ]  with that figure growing to 16% by 2022, according to the World Health Organisation  [ 219 ]  The percentage of adults affected in the United States as of 2015–2016 is about 39.6% overall (37.9% of males and 41.1% of females). [ 220 ]  In 2000, the  World Health Organization  (WHO) stated that  overweight  and obesity were replacing more traditional  public health  concerns such as  undernutrition  and  infectious diseases  as one of the most significant cause of poor health. [ 221 ]


The rate of obesity also increases with age at least up to 50 or 60 years old [ 52 ] : 5   and severe obesity in the United States, Australia, and Canada is increasing faster than the overall rate of obesity. [ 30 ] [ 222 ] [ 223 ]  The  OECD  has projected an increase in obesity rates until at least 2030, especially in the United States, Mexico and England with rates reaching 47%, 39% and 35%, respectively. [ 224 ]


Once considered a problem only of high-income countries, obesity rates are rising worldwide and affecting both the developed and developing world. [ 225 ]  These increases have been felt most dramatically in urban settings. [ 217 ]


Sex- and gender-based differences also influence the prevalence of obesity. Globally there are more obese women than men, but the numbers differ depending on how obesity is measured. [ 226 ] [ 227 ]


Obesity  is from the  Latin   obesitas , which means "stout, fat, or plump".  Ēsus  is the past participle of  edere  (to eat), with  ob  (over) added to it. [ 228 ]   The Oxford English Dictionary  documents its first usage in 1611 by  Randle Cotgrave . [ 229 ]


Ancient Greek medicine  recognizes obesity as a medical disorder and records that the Ancient Egyptians saw it in the same way. [ 215 ]   Hippocrates  wrote that "Corpulence is not only a disease itself, but the harbinger of others". [ 2 ]  The Indian surgeon  Sushruta  (6th century BCE) related obesity to diabetes and heart disorders. [ 231 ]  He recommended physical work to help cure it and its side effects. [ 231 ]  For most of human history, mankind struggled with food scarcity. [ 232 ]  Obesity has thus historically been viewed as a sign of wealth and prosperity. It was common among high officials in Ancient East Asian civilizations. [ 233 ]  In the 17th century, English medical author  Tobias Venner  is credited with being one of the first to refer to the term as a societal disease in a published English language book. [ 215 ] [ 234 ]


With the onset of the  Industrial Revolution , it was realized that the military and economic might of nations were dependent on both the body size and strength of their soldiers and workers. [ 115 ]  Increasing the average body mass index from what is now considered underweight to what is now the normal range played a significant role in the development of industrialized societies. [ 115 ]  Height and weight thus both increased through the 19th century in the developed world. During the 20th century, as populations reached their genetic potential for height, weight began increasing much more than height, resulting in obesity. [ 115 ]  In the 1950s, increasing wealth in the developed world decreased child mortality, but as body weight increased, heart and kidney disease became more common. [ 115 ] [ 235 ]
During this time period, insurance companies realized the connection between weight and life expectancy and increased premiums for the obese. [ 2 ]


Many cultures throughout history have viewed obesity as the result of a character flaw. The  obesus  or fat character in  Ancient Greek comedy  was a glutton and figure of mockery. During Christian times, food was viewed as a gateway to the sins of  sloth  and  lust . [ 20 ]  In modern Western culture, excess weight is often regarded as unattractive, and obesity is commonly associated with various negative stereotypes. People of all ages can face social stigmatization and may be targeted by bullies or shunned by their peers. [ 236 ]


Public perceptions in Western society regarding healthy body weight differ from those regarding the weight that is considered ideal – and both have changed since the beginning of the 20th century. The weight that is viewed as an ideal has become lower since the 1920s. This is illustrated by the fact that the average height of Miss America pageant winners increased by 2% from 1922 to 1999, while their average weight decreased by 12%. [ 237 ]  On the other hand, people's views concerning healthy weight have changed in the opposite direction. In Britain, the weight at which people considered themselves to be overweight was significantly higher in 2007 than in 1999. [ 238 ]  These changes are believed to be due to increasing rates of adiposity leading to increased acceptance of extra body fat as being normal. [ 238 ]


Obesity is still seen as a sign of wealth and well-being in many parts of Africa. This has become particularly common since the  HIV  epidemic began. [ 2 ]


The first sculptural representations of the human body 20,000–35,000 years ago depict obese females. Some attribute the  Venus figurines  to the tendency to emphasize fertility while others feel they represent "fatness" in the people of the time. [ 20 ]  Corpulence is, however, absent in both Greek and Roman art, probably in keeping with their ideals regarding moderation. This continued through much of Christian European history, with only those of low socioeconomic status being depicted as obese. [ 20 ]


During the  Renaissance  some of the upper class began flaunting their large size, as can be seen in portraits of  Henry VIII of England  and  Alessandro dal Borro . [ 20 ]   Rubens  (1577–1640) regularly depicted heavyset women in his pictures, from which derives the term  Rubenesque . These women, however, still maintained the "hourglass" shape with its relationship to fertility. [ 239 ]  During the 19th century, views on obesity changed in the Western world. After centuries of obesity being synonymous with wealth and social status, slimness began to be seen as the desirable standard. [ 20 ]  In his 1819 print,  The Belle Alliance, or the Female Reformers of Blackburn!!!,  artist  George Cruikshank  criticised the work of female reformers in  Blackburn  and used fatness as a means to portray them as unfeminine. [ 240 ]


In addition to its health impacts, obesity leads to many problems, including disadvantages in employment [ 241 ] : 29  [ 242 ]  and increased business costs.


In 2005, the medical costs attributable to obesity in the US were an estimated $190.2 billion or 20.6% of all medical expenditures, [ 243 ] [ 244 ] [ 245 ]  while the cost of obesity in Canada was estimated at CA$2 billion in 1997 (2.4% of total health costs). [ 96 ]  The total annual direct cost of overweight and obesity in Australia in 2005 was A$21 billion. Overweight and obese Australians also received A$35.6 billion in government subsidies. [ 246 ]  The estimated range for annual expenditures on diet products is $40 billion to $100 billion in the US alone. [ 247 ]


The Lancet  Commission on Obesity in 2019 called for a global treaty—modelled on the  WHO Framework Convention on Tobacco Control —committing countries to address obesity and undernutrition, explicitly excluding the food industry from policy development. They estimate the global cost of obesity $2 trillion a year, about or 2.8% of world GDP. [ 248 ]


Obesity prevention programs have been found to reduce the cost of treating obesity-related disease. However, the longer people live, the more medical costs they incur. Researchers, therefore, conclude that reducing obesity may improve the public's health, but it is unlikely to reduce overall health spending. [ 249 ]  Sin taxes such as a  sugary drink tax  have been implemented in certain countries globally to curb dietary and consumer habits, and as an effort to offset the economic tolls.


Obesity can lead to social stigmatization and disadvantages in employment. [ 241 ] : 29   When compared to their ideal weight counterparts, workers with obesity, on average have higher rates of absenteeism from work and take more disability leave, thus increasing costs for employers and decreasing productivity. [ 251 ]  A study examining Duke University employees found that people with a BMI over 40 kg/m 2  filed twice as many  workers' compensation  claims as those whose BMI was 18.5–24.9 kg/m 2 . They also had more than 12 times as many lost work days. The most common injuries in this group were due to falls and lifting, thus affecting the lower extremities, wrists or hands, and backs. [ 252 ]  The Alabama State Employees' Insurance Board approved a controversial plan to charge obese workers $25 a month for health insurance that would otherwise be free unless they take steps to lose weight and improve their health. These measures started in January 2010 and apply to those state workers whose BMI exceeds 35 kg/m 2  and who fail to make improvements in their health after one year. This becomes a Catch 22 position as many insurance companies will refuse to pay for treatment methods for workers living with obesity. [ 253 ]


Some research shows that people with obesity are less likely to be hired for a job and are less likely to be promoted. [ 236 ]  People with obesity are also paid less than their counterparts who do not live with obesity for an equivalent job; women with obesity on average make 6% less and men with obesity make 3% less. [ 241 ] : 30


Specific industries, such as the airline, healthcare and food industries, have special concerns. Due to rising rates of obesity, airlines face higher fuel costs and pressures to increase seating width. [ 254 ]  In 2000, the extra weight of passengers with obesity cost airlines US$275 million. [ 255 ]  The healthcare industry has had to invest in special facilities for handling  patients with class III obesity, including special lifting equipment and  bariatric ambulances . [ 256 ]  Costs for restaurants are increased by litigation accusing them of causing obesity. [ 257 ]  In 2005, the US Congress discussed legislation to prevent civil lawsuits against the food industry in relation to obesity; however, it did not become law. [ 257 ]


With the  American Medical Association 's 2013 classification of obesity as a chronic disease, [ 23 ]  it is thought that health insurance companies will more likely pay for obesity treatment, counseling and surgery, and the cost of research and development of adipose treatment pills or gene therapy treatments should be more affordable if insurers help to subsidize their cost. [ 258 ]  The AMA classification is not legally binding, however, so health insurers still have the right to reject coverage for a treatment or procedure. [ 258 ]


In 2014, The European Court of Justice ruled that morbid obesity is a disability. The Court said that if an employee's obesity prevents them from "full and effective participation of that person in professional life on an equal basis with other workers", then it shall be considered a disability and that firing someone on such grounds is discriminatory. [ 259 ]


In low-income countries, obesity can be a signal of wealth. A 2023 experimental study found that obese individuals in Uganda were more likely to access credit. [ 260 ]


The principal goal of the fat acceptance movement is to decrease discrimination against people who are overweight and obese. [ 262 ] [ 263 ]  However, some in the movement are also attempting to challenge the established relationship between obesity and negative health outcomes. [ 264 ]


A number of organizations exist that promote the acceptance of obesity. They have increased in prominence in the latter half of the 20th century. [ 265 ]  The US-based  National Association to Advance Fat Acceptance  (NAAFA) was formed in 1969 and describes itself as a civil rights organization dedicated to ending size discrimination. [ 266 ]


The  International Size Acceptance Association  (ISAA) is a  non-governmental organization  (NGO) which was founded in 1997. It has more of a global orientation and describes its mission as promoting size acceptance and helping to end weight-based discrimination. [ 267 ]  These groups often argue for the recognition of obesity as a disability under the US  Americans With Disabilities Act  (ADA). The American legal system, however, has decided that the potential public health costs exceed the benefits of extending this anti-discrimination law to cover obesity. [ 264 ]


In 2015, the  New York Times  published an article on the  Global Energy Balance Network , a nonprofit founded in 2014 that advocated for people to focus on increasing exercise rather than reducing calorie intake to avoid obesity and to be healthy. The organization was founded with at least $1.5M in funding from the  Coca-Cola Company , and the company has provided $4M in research funding to the two founding scientists Gregory A. Hand and  Steven N. Blair  since 2008. [ 268 ] [ 269 ]


Many organizations have published reports pertaining to obesity. In 1998, the first US Federal guidelines were published, titled "Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults: The Evidence Report". [ 270 ]  In 2006, the  Canadian Obesity Network , now known as  Obesity Canada  published the "Canadian Clinical Practice Guidelines (CPG) on the Management and Prevention of Obesity in Adults and Children". This is a comprehensive evidence-based guideline to address the management and prevention of overweight and obesity in adults and children. [ 96 ]


In 2004, the United Kingdom  Royal College of Physicians , the  Faculty of Public Health  and the  Royal College of Paediatrics and Child Health  released the report "Storing up Problems", which highlighted the growing problem of obesity in the UK. [ 271 ]  The same year, the  House of Commons   Health Select Committee  published its "most comprehensive inquiry [...] ever undertaken" into the impact of obesity on health and society in the UK and possible approaches to the problem. [ 272 ]  In 2006, the  National Institute for Health and Clinical Excellence  (NICE) issued a guideline on the diagnosis and management of obesity, as well as policy implications for non-healthcare organizations such as local councils. [ 273 ]  A 2007 report produced by  Derek Wanless  for the  King's Fund  warned that unless further action was taken, obesity had the capacity to debilitate the  National Health Service  financially. [ 274 ]  In 2022 the  National Institute for Health and Care Research  (NIHR) published a comprehensive review of research on what  local authorities  can do to reduce obesity. [ 199 ]


The Obesity Policy Action (OPA) framework divides measure into  upstream  policies,  midstream  policies, and  downstream  policies. Upstream policies have to do with changing society, while midstream policies try to alter behaviors believed to contribute to obesity at the individual level, while downstream policies treat currently obese people. [ 275 ]


The healthy BMI range varies with the age and sex of the child. Obesity in children and adolescents is defined as a BMI greater than the 95th  percentile . [ 276 ]  The reference data that these percentiles are based on is from 1963 to 1994 and thus has not been affected by the recent increases in rates of obesity. [ 277 ]  Childhood obesity has reached epidemic proportions in the 21st century, with rising rates in both the developed and the developing world. Rates of obesity in Canadian boys have increased from 11% in the 1980s to over 30% in the 1990s, while during this same time period rates increased from 4 to 14% in Brazilian children. [ 278 ]  In the UK, there were 60% more obese children in 2005 compared to 1989. [ 279 ]  In the US, the percentage of overweight and obese children increased to 16% in 2008, a 300% increase over the prior 30 years. [ 280 ]


As with obesity in adults, many factors contribute to the rising rates of childhood obesity. Changing diet and decreasing physical activity are believed to be the two most important causes for the recent increase in the incidence of child obesity. [ 281 ]   Advertising of unhealthy foods to children  also contributes, as it increases their consumption of the product. [ 282 ]  Antibiotics in the first 6 months of life have been associated with excess weight at age seven to twelve years of age. [ 166 ]  Because childhood obesity often persists into adulthood and is associated with numerous chronic illnesses, children who are obese are often tested for  hypertension ,  diabetes ,  hyperlipidemia , and  fatty liver disease . [ 96 ]


Treatments used in children are primarily lifestyle interventions and behavioral techniques, although efforts to increase activity in children have had little success. [ 283 ]  In the United States, medications are not FDA approved for use in this age group. [ 278 ]  Brief weight management interventions in  primary care  (e.g. delivered by a physician or nurse practitioner) have only a marginal positive effect in reducing childhood overweight or obesity. [ 284 ]  Multi-component behaviour change interventions that include changes to dietary and physical activity may reduce BMI in the short term in children aged 6 to 11 years, although the benefits are small and quality of evidence is low. [ 285 ]


Obesity in pets is common in many countries. In the United States, 23–41% of dogs are overweight, and about 5.1% are obese. [ 286 ]  The rate of obesity in cats was slightly higher at 6.4%. [ 286 ]  In Australia, the rate of obesity among dogs in a veterinary setting has been found to be 7.6%. [ 287 ]  The risk of obesity in dogs is related to whether or not their owners are obese; however, there is no similar correlation between cats and their owners. [ 288 ]


Obesity and the environment  aims to look at the different  environmental factors  that researchers worldwide have determined cause and perpetuate  obesity . Obesity is a condition in which a person's weight is higher than what is considered healthy for their height, and is the leading cause of preventable death worldwide. Obesity can result from several factors such as poor nutritional choices, overeating, genetics, culture, and metabolism. [ 1 ]  Many diseases and health complications [ 2 ]  are associated with obesity (e.g., Type-II diabetes, heart disease, cancer, stroke). Worldwide, the rates of obesity have nearly tripled since 1975, leading health professionals to label the condition as a modern epidemic in most parts of the world. Current (as of 2022) worldwide population estimates of obese adults are near 13%; overweight adults total approximately 39%. [ 1 ]


Studies have shown that  obesity  has become increasingly prevalent in both people and animals (pets and laboratory animals). [ 3 ]  Proper diet and exercise is not linked to lower obesity rates or the trending toward obesity despite these being the assumed cure and preventative for obesity. According to Professor  Robert H. Lustig  from the  University of California, San Francisco , "[E]ven those at the lower end of the  body mass index  (BMI) curve are gaining weight. Whatever is happening is happening to everyone, suggesting an environmental trigger." [ 4 ]  The theory of environmental  obesogens  proposes a different causal facet to obesity – that lifetime exposure to  xenobiotic  chemical obesogens, molecules that do not properly regulate  lipid metabolism  in the body and may cause obesity, changes the body's metabolic system. Data is scarce, but some in-vitro studies have found this model could be an accurate predictor of future obesity. A study suggested that smoking before and during pregnancy, for example, increases the risk of obesity twofold in children of school age. [ 5 ]


Many chemicals in common-use products are known or suspected to be obesogens and act as  endocrine disruptors  in the body. In a  University at Albany, State University of New York  study,  organotin compounds , toxic chemicals derived from tin and hydrocarbon substituents, were found in a designer handbag, vinyl blinds, wallpaper, tile, and vacuum cleaner dust collected from 20 houses. [ 6 ]  The study linked obesity to  phthalates , present in many PVC items, in addition to scented items like fresheners, laundry products, and personal care products. [ 7 ]  Also linked is  Bisphenol A  (BPA), a known environmental obesogen that reduces the body's overall number of fat cells but which makes remaining fat cells larger. Additionally, glucose intolerance and more abdominal fat were found to be the results of obesogens in animals and the long-term effects of low-birth weight babies. [ 6 ]   The study strongly indicates that obesogens change an individual's metabolic set points for gaining weight. [ 6 ]


Research on obesogens indicate some  endocrine disrupting chemicals  (EDCs) belong to this class of compounds. Bruce Blumberg, a professor of developmental and cell biology at  UC Irvine , has found compelling evidence that exposure to the chemical  Tributyltin  (TBT), a compound used in  pesticides , can trigger fat cell creation. [ 8 ]


As several cases have confirmed, farm workers in America have unwillingly or unknowingly worked in fields that had been recently sprayed with TBT and other dangerous chemicals. Among a wide variety of health risks, farm workers may bear a disproportionate risk of exposure to such obesogens. While legislation has been enacted to require a minimum amount of time to pass before workers enter sprayed fields, the lack of legal and political power of many farm workers combined with the fact that enforcing such laws can be difficult, makes exposure to obesogens a possible threat to the livelihood of many farm workers.


The country to country rates of obese adults in a total population vary due to different environments, lifestyles, and diets. While there is no direct correlation between obesity rates and economic status, wealthier countries have more resources to utilize for health and fitness awareness. [ 9 ]  According to World Population Review, in 2022 all of the top ten countries with the highest percentage of obese adults are found in the South Pacific. Several theories attempt to explain this fact, including the popularity of unhealthy fast food, the use of frying as a means to prepare food, and possible genetic predispositions. In contrast, the country with the lowest percentage of total obese adults is Vietnam, with only 2.1%, attributed to chronic food insecurity and child malnutrition. [ 1 ]


In the United States, the prevalence of obese adults in the mid-1990's was substantially lower than current figures. In 1994, the prevalence of obesity in every state was less than 22%, but by 2000, 11 states (Alabama, Arkansas, Kentucky, Louisiana, Michigan, Mississippi, Missouri, South Carolina, Tennessee, Texas, and West Virginia) had surpassed that figure. Six states had a population percentage of obese adults of more than 30%; the remaining states ranged between 20% and 30%. By 2015, no state had a prevalence of obesity under 18%; almost all states exceeded 22%, and six states exceeded 26%. [ 10 ]   According to the  Centers for Disease Control and Prevention  (CDC), in 2016 the number of obese people in the United States reached an all-time high of about 93 million, up 33% from 2008. [ 11 ]  By 2020, the U.S, obesity prevalence was 41.9%, an increase from 30.5% in 2017 to 41.9% in 2020. During the same time, the prevalence of severe obesity increased from 4.7% to 9.2%. [ 12 ]


Race and genetics are two other dimensions of obesity that have been extensively studied. Some researchers have found that genetics increase the likelihood of occurrence of obesity through higher levels of fat deposition and  adipokine  secretion. [ 13 ]  Other critics suggest that race itself may affect the way obesity presents itself in individuals. In a recent study of 70,000 men and women of African ancestry, researchers found three new common genetic variants. [ 14 ]  These  single-nucleotide polymorphisms  (SNPs) are connected to body mass index (BMI) and obesity. Therefore, individuals who carry these variants are more at risk of becoming obese. Researchers noted that these genetic variants are very small determinants in most cases of obesity. Most medical professionals agree that  environmental factors , poor health, and eating habits are still considered to be the strongest contributors of obesity. [ 15 ]


One study found that Black men and women have a lower percentage of body fat than White men and women with the same  body mass index  (BMI). [ 16 ]   A similar study concluded that obese Black adolescents had significantly less dangerous visceral fat than obese White adolescents. This finding is significant because visceral fat has been more strongly linked to the risk of disease compared to fat stored in other parts of the body. [ 17 ]


Between 1980 and 2000, obesity rates in the United States doubled among young children and tripled among teens. Numerous studies aimed to provide insight into genetic, economic, and/or environmental causes of obesity. According to the " thrifty gene hypothesis , [ 18 ]  a genetic theory explaining rising obesity rates, certain individuals are genetically predisposed to metabolize food more efficiently than others as a result of human evolution. In times of scarcity, these genes were essential in ensuring survival; in times of abundance, these same genes cause obesity. In first-world countries like the United States, the UK, Australia, and most Western European countries, evolution has led to an increased sedentary lifestyle and high rates of sugar and fat consumption, directly leading to obesity.


According to the CDC, studies show that members of racial and ethnic minority communities are disproportionately obese. Hispanics (47%) and non-Hispanic Blacks (46.8%) had the highest age-adjusted prevalence of obesity compared to non-Hispanic Whites (37.9%) and non-Hispanic Asians (12.7%). [ 19 ]  A similar study in the  American Journal of Public Health  found a strong correlation between community demographics and the likelihood of obesity: Hispanics (28.7%) and non-Hispanic Blacks (36.1%) evidenced higher percentages of obesity than non-Hispanic Whites (24.5%) and non-Hispanic Asians (7.1%). [ 20 ]  Many theories exist to explain these disparities, including differing dietary behaviors among ethnic groups, differing cultural norms in regards to body weight and size, and unequal access to healthy foods. [ 21 ]  Due to economic factors, many Hispanics and non-Hispanic Blacks rely on cheap calories with little nutritional value. According to television broadcast statistics, Hispanic and Black teens and children are specifically targeted by fast food restaurants. Spanish-language TV advertisement has increased by 8%, and restaurants such as KFC and Burger King have increased their spending on Spanish advertisements from 35% to 41% while decreasing English-language advertising. [ 22 ]


The Department of Agriculture defines  food deserts  as neighborhoods without ready access to fresh, healthy, and affordable food. Communities suffering in food deserts are more likely to be Hispanic and Black neighborhoods, limiting available healthy food options. In 2015, Chicago's Mayor Emmanuel partnered with Growing Power, which transported affordable fresh fruits and vegetables to food desert areas. [ 23 ]   In 2004, Pennsylvania enacted a $100 million economic stimulus package that subsidized grocery stores by offering a low-cost business loan from the Fresh Food Financing Initiative (FFFI) if they were located in a food desert. [ 23 ]  In 2008, former New York City Mayor Bloomberg introduced the Green Cart amendment, which allowed pushcart vendors to receive a low-cost permit if they were willing to operate in under-served neighborhoods. The Green Cart program projected an improvement in the health of 75,000 New Yorkers, and save at least 50 lives a year over the long term. [ 23 ]


Hispanic and Black communities frequently have less access to exercise and fitness opportunities (i.e., public parks) as well as healthy green spaces which creates a obesogenic environment. [ 24 ] [ 25 ]  Low income neighborhoods are burdened with an abundance of fast food outlets. A 2005 study conducted in Chicago found that Black neighborhoods had 14 fast food restaurants per 100,000 neighborhood residents, while White neighborhoods had 9.4 fast food restaurants per 100,000 residents. Fast food restaurants offer inexpensive, calorie-dense food that is nutrient-poor and unhealthy with high levels of sugar, fat, and sodium. According to the USDA recommendation for daily caloric intake, a McDonald's meal has more than half a day's worth of calories. [ 26 ]  In the short term, the residents of these communities are making an economically rational decision when purchasing fast food as it is easily accessible and inexpensive. The alternative would be purchasing low quality groceries at a high cost. [ 27 ]  In the long-term, however, studies show that the consumption of fast food hurts overall health, raising the probability of becoming obese. [ 28 ]


Economic status of individuals in ethnic groups does not fully explain the disparity between communities. A 2009 study in the  Journal of Epidemiology and Community Health  found that racial/ethnic minorities have a higher risk of being obese within each observed socioeconomic group, [ 29 ]  suggesting that race is a key indicator in determining disparities of obesity risk. The study also implies that  structural racism  may cause certain racial/ethnic groups to experience a disproportionate risk of obesity.


Weight bias  is an ongoing field of study focusing on obesity-related stigmatization. Multiple academics cite evidence of differential, negative treatment of the overweight and obese due to commonly attributed  stereotypes  such as laziness, incompetence, weakness of will, sloppiness, and untrustworthiness. [ 30 ] [ 31 ]


In one study of 2,249 obese and overweight women, 54% reported experiencing weight stigma by their colleagues; 43% reported experiencing weight stigma by their superiors. Weight stigma can be defined as derogatory comments, preferential treatment towards average-weight colleagues, and denial of employment. In another study of 2,838 nationally representative adults aged 25–74, overweight, obese, and severely obese respondents were, respectively, 12, 37, and 100 times more likely to report  employment discrimination  than average-weight respondents, including loss or reduction of wages. Data suggests that after controlling for other socioeconomic factors, limitations of health, and other household variables, obese men were expected to see a 0.7 to 3.4% wage depression, and obese women were expected to see a wage depression between 2.3 and 6.1%. [ 32 ]


Studies show that physicians are most likely to attribute lack of motivation as the primary cause of obesity, coupled with non-compliance and general laziness. In one United Kingdom study, physicians tended to follow a  victim-blaming  approach regarding the causes of obesity, while the obese patients themselves attributed their weight to specific medical causes or other socioeconomic factors, such as low income. Disparities in perceived causation are a major hindrance towards physicians' and patients' abilities to create and maintain a balanced obesity management plan. [ 32 ]


Educational weight bias also presents in the correlation between obesity and educational attainment. A study of over 700,000 Swedish men found that, after controlling for intelligence and parental socioeconomic levels, those who were obese at the age of 18 had a lower chance of going to college than their average-weight peers. Similarly, a study based on data gathered by the  National Longitudinal Study of Adolescent Health  concluded that obese women were 50% less likely to attend college than their average-sized peers. Female students who attended school where most of the females were obese, however, had a relatively similar chance of attending college as non-obese women. [ 32 ]


Weight bias, fat stigma, and discrimination are factors that many academics say can contribute to hopelessness and depression, encouraging the same unhealthy habits that initially caused obesity. [ 33 ]


Scientific and healthcare communities agree that obesity and mental illness are directly related. Awareness of the complicated relationship between these health concerns will develop solutions that are as of yet inaccessible. Patients assessed for obesity need to be examined with respect to their mental health status. Public health policies should recognize frequently paired mental illness and weight-related disorders and their influence on and from cultural, gender, socioeconomic, and other health elements. Policy and training should also highlight the likelihood of the obese developing mental health co-morbid disorders, and vice versa. Training health professionals with a focus on interventions, support, prevention, and collaboration with related specialties is crucial.


Obesity is a chronic health condition associated with extreme conditions in mental health. A variety of psychological disorders or mental illnesses such as eating disorders (anorexia, bulimia, binge-eating disorder), schizophrenia, bipolar disorder, and depression/anxiety, are associated with an increased risk of obesity and other obesity-related illnesses like diabetes and coronary heart disease. A 2014 study of over 10,000 people suffering from schizophrenia, bipolar disorder, or depression showed that 80% of the participants were overweight or obese. [ 34 ]  Psychological issues obesity can trigger include low self-esteem, distorted body image, and body shaming. Obese individuals tend to have higher rates of depression than those who are not obese. Research at the  University of Wisconsin-Madison  by Dr. David A. Kats and his colleagues indicated that of the 2,931 patients tested exhibiting chronic health conditions, clinical depression was highest in extremely obese patients (patients with a BMI over 35). A Swedish Obese Subjects (SOS) research study indicated that clinically significant depression is about three- to four-times higher in severely obese individuals than in those who are not obese. Professor Marianne Sullivan and her team from  Sahlgrenska University Hospital  noted that obese subjects exhibited depression scores similar to patients living with chronic pain. [ 35 ] [ 36 ]


Children tend to be less active when their communities lack safe play areas and after-school programs regardless of their community's socioeconomic status. Rates of after-school program participation are low across all socioeconomic groups; current research shows that this may be due to external factors other than willingness or a need to participate. Research indicates children that come from high socioeconomic households typically do not participate in after-school programs because they are already involved in a wide range of extra-curricular activities. Children that come from low-socioeconomic households, however, typically do not utilize play spaces and after-school programs due to lack of ability and frequently a lack of transportation. [ 37 ] [ 38 ] [ 39 ]  The CCLC, an after-school program serving low-income youth, conducted a survey in which 20% of youth responders cite transportation, rather than a lack of interest or willingness, as the primary reason they do not attend after-school programs. [ 40 ]  Additionally, parents of low-income and minority youth are less likely to have easy access to after-school programs as compared to high-income and White parents.


Disadvantaged youth and young adults face similar problems with transportation to safe and engaging spaces. Poor youth are less likely to have access to a car, and more likely to live in high crime neighborhoods, making it difficult to take public transportation or walk. Additionally, children from disadvantaged families often have more worries and less free time to exercise, as they struggle alongside family members to find ways to meet their basic needs. By contrast, privileged families have the financial means and time to take their children to playgrounds, after-school activities, competitive sports, and more.


Children of higher-class families have more access to technology and tend to make less use of the " environmental space " of their everyday life; such technology removes opportunities for youth outdoor interaction. Children with frequent access to technology tend to spend more time indoors engaged with a computer/television screen rather than playing outdoors. [ 41 ]  In this sense, technology is a detriment to children as it frequently hampers physical activity, thus negatively impacting a child's health. This issue contradicts the belief held by many in the United States that children who come from high-income homes are less likely to become obese as they can be active in safe environmental spaces.


Technology also plays a detrimental role for adults who spend most of their time working on a computer. Economists from the  Milken Institute , working with statistics from the United States, correlated a 10% increase in the sale of technology with a 1.4% increase in obesity rates – approximately 4.2 million people in a country with the same population as the United States. [ 42 ]  This increase in time spent using technology not only absorbs time potentially spent being active, it also changes the way people eat. Employees may feel pressured while at work and may eat hurriedly or absentmindedly; once home, workers frequently turn on the TV or engage in their mobile phones instead of focusing on their food consumption and diet. Ross DeVol, a chief research officer at the Milken Institute, quipped: "Common sense says if you sit around in front of the screen, don't exercise while you are working, change your diet...you are going to gain weight." [ 43 ]


In 2009, the  U.S. Department of Agriculture  conducted a food desert study to examine the public's access to supermarkets. Evidence showed that 23.5 million people within the United States did not have access to a supermarket within a one-mile radius of their residence. More than 113 studies have been conducted to determine if healthy food and supermarkets are equally distributed and accessible to every socioeconomic class. Of these, 85% (97) of the studies found that supermarkets and healthy food stores are unequally distributed between different socioeconomic groups. [ 44 ]


Other research teams have studied the comparison between supermarkets and smaller food outlets such as small grocery stores and convenience stores. They found that supermarkets were used as a proxy for food access as they provide the most reliable access to a wide variety of nutritious and affordable food. The study showed that low-income and minority communities had less supermarkets and more convenience and small grocery stores as compared to predominantly wealthy and White communities. 89 out of the 98 (90%) studies of national data indicated that urban areas have uneven geographic access to supermarkets.


National studies have concluded that ZIP codes composed primarily of low-income households are 25% less likely to have a chain supermarket store but contain 1.3 times as many convenient stores when compared to ZIP codes composed of middle-income households. ZIP codes composed of predominantly African-American households have about half the amount of chain supermarkets, as do ZIP codes composed of predominantly White households. [ 45 ]  An assessment of 685 urban and rural census tracts spanning three states show that low-income neighborhoods have approximately half as many supermarkets and four times as many small grocery stores when compared to high-income neighborhoods. The same study also found that predominantly White neighborhoods have four times as many supermarkets as predominantly African-American neighborhoods. [ 46 ]  Also, a study of 10,763 residences in four states reported the existence of supermarkets in the surveyed residential area was directly related with a 24% lower prevalence of obesity and a 9% lower prevalence of overweight residents. [ 47 ]


Studies done at the local level demonstrate similar trends to those done at the national level. There are 2.3 times as many supermarkets per household in low-poverty areas in  Los Angeles  compared to high-poverty areas. Predominantly white regions have 1.7 times as many supermarkets as Hispanic regions, and 3.2 times as many as African-American regions. [ 48 ]   West Louisville, Kentucky , a low-income African-American community that suffers from high rates of diabetes, has one supermarket for every 25,000 residents; in comparison, the U.S. in total has an average of one supermarket for every 12,500 residents. [ 49 ]  In Washington, DC, the city's lowest income wards (Wards 7 and 8) have one supermarket for every 70,000 people, while two of the three highest-income wards (Wards 2 and 3) have one for every 11,881 people. One in five of the city's  food stamp  recipients lives in a neighborhood without a grocery store. [ 50 ]  Twenty-one studies have found that food stores in low-income communities are less likely to stock healthy or fresh food or snacks, and are instead more likely to offer lower quality items at higher prices, compared to food stores in predominantly white communities. [ 51 ] [ 52 ] [ 53 ] [ 54 ]


The  Child Nutrition and WIC Reauthorization Act of 2004  created the team nutrition network to promote healthy eating and physical activity in school-aged children, awarding grants to states that created healthy eating and physical activity programs for the children they serve. [ 55 ]  The CDC released its own guidelines for schools to promote physical and health education for schoolchildren, specifically suggesting that public and private schools: