obesity obesity obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect 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/m2; the range 25–30 kg/m2 is defined as overweight. some east asian countries use lower values to calculate obesity. 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. obesitysilhouettes and waist circumferences representing optimal, overweight, and obesespecialtyendocrinologysymptomsincreased fatcomplicationscardiovascular diseases, type 2 diabetes, obstructive sleep apnea, certain types of cancer, osteoarthritis, depressioncausesexcessive consumption of energy-dense foods, sedentary work and lifestyles and lack of physical activity, changes in modes of transportation, urbanization, lack of supportive policies, lack of access to a healthy diet, geneticsdiagnostic methodbmi > 30 kg/m2preventionsocietal changes, changes in the food industry, access to a healthy lifestyle, personal choicestreatmentdiet, exercise, medications, surgeryprognosisreduced life expectancyfrequency700 million / 12% (2015)deaths2.8 million people per year part of a series onhuman body weight general concepts obesity (epidemiology) overweight underweight body shape weight gain weight loss gestational weight gain diet (nutrition) weight management overnutrition childhood obesity (epidemiology) medical concepts adipose tissue classification of obesity genetics of obesity metabolic syndrome (epidemiology of metabolic syndrome) metabolically healthy obesity obesity paradox set point theory measurements body adiposity index body mass index body fat percentage body shape index corpulence index lean body mass relative fat mass waist–hip ratio waist-to-height ratio related conditions diabetes (type 1) eating disorder (anorexia • bulimia • binge eating disorder) food addiction hyperthyroidism malnutrition red-s starvation (starvation response) pcos obesity-associated morbidity arteriosclerosis atherosclerosis fatty liver disease gerd gynecomastia heart disease hypertension obesity and cancer osteoarthritis prediabetes sleep apnea type 2 diabetes management of obesity anti-obesity medication bariatrics bariatric surgery dieting (list of diets) caloric deficit exercise (outline) liposuction obesity medicine weight loss camp weight loss coaching yo-yo effect social aspects comfort food fast food (criticism) fat acceptance movement fat fetishism health at every size hunger obesity and the environment obesity and sexuality sedentary lifestyle social determinants of obesity social stigma of obesity weight cutting weight class 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. while a majority of obese individuals at any given time are attempting to lose weight and are often successful, maintaining weight loss long term is rare. there is no effective, well-defined, evidence-based intervention for preventing obesity. obesity prevention requires a complex approach, including interventions at societal, community, family, and individual levels. changes to diet and exercising are the main treatments recommended by health professionals. 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, if these dietary choices are available, affordable, and accessible. medications can be used, along with a suitable diet, to reduce appetite or decrease fat absorption. 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. obesity is a leading preventable cause of death worldwide, with increasing rates in adults and children. in 2015, 600 million adults (12%) and 100 million children were obese in 195 countries. obesity is more common in women than in men. 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. nevertheless, in 2013, several medical societies, including the american medical association and the american heart association, classified obesity as a disease. classification main article: classification of obesity category bmi (kg/m2) underweight < 18.5 normal weight 18.5 – 24.9 overweight 25.0 – 29.9 obese (class i) 30.0 – 34.9 obese (class ii) 35.0 – 39.9 obese (class iii) ≥ 40.0 a "super obese" male with a bmi of 53 kg/m2: weight 182 kg (401 lb), height 185 cm (6 ft 1 in). he presents with stretch marks and enlarged breasts. obesity is typically defined as a substantial accumulation of body fat that could impact health. medical organizations tend to classify people as obese 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 "obese" as a bmi 30 or higher. 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. 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). for children under five, the who defines obesity as a weight three standard deviations above the median for their height. some modifications to the who definitions have been made by particular organizations. the surgical literature breaks down class ii and iii or only class iii obesity into further categories whose exact values are still disputed. any bmi ≥ 35 or 40 kg/m2 is severe obesity. a bmi of ≥ 35 kg/m2 and experiencing obesity-related health conditions or ≥ 40 or 45 kg/m2 is morbid obesity. a bmi of ≥ 45 or 50 kg/m2 is super obesity. 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/m2 while china uses a bmi of greater than 28 kg/m2. 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%. levels in excess of 32% for women and 25% for men are generally considered to indicate obesity. bmi 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. however, their mean body fat percentage, 14%, is well within what is considered a healthy range. 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). 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. effects on health obesity increases a person's risk of developing various metabolic diseases, cardiovascular disease, osteoarthritis, alzheimer disease, depression, and certain types of cancer. depending on the degree of obesity and the presence of comorbid disorders, obesity is associated with an estimated 2–20 year shorter life expectancy. high bmi is a marker of risk for, but not a direct cause of, diseases caused by diet and physical activity. mortality relative risk of death over 10 years in white people who have never smoked in the united states by bmi. the bmi range 22.5 to 24.9 is set as the reference. obesity is one of the leading preventable causes of death worldwide. the mortality risk is lowest at a bmi of 20–25 kg/m2 in non-smokers and at 24–27 kg/m2 in current smokers, with risk increasing along with changes in either direction. this appears to apply in at least four continents. 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. in asians the risk of negative health effects begins to increase between 22 and 25 kg/m2. in 2021, the world health organization estimated that obesity caused at least 2.8 million deaths annually. on average, obesity reduces life expectancy by six to seven years, a bmi of 30–35 kg/m2 reduces life expectancy by two to four years, while severe obesity (bmi ≥ 40 kg/m2) reduces life expectancy by ten years. morbidity main article: obesity-associated morbidity obesity increases the risk of many physical and mental conditions. these comorbidities are most commonly shown in metabolic syndrome, a combination of medical disorders which includes: diabetes mellitus type 2, high blood pressure, high blood cholesterol, and high triglyceride levels. a study from the rak hospital found that obese people are at a greater risk of developing long covid. the cdc has found that obesity is the single strongest risk factor for severe covid-19 illness. 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. 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). increases in body fat alter the body's response to insulin, potentially leading to insulin resistance. increased fat also creates a proinflammatory state, and a prothrombotic state. medical field condition medical field condition cardiology coronary heart disease: angina and myocardial infarction congestive heart failure high blood pressure abnormal cholesterol levels deep vein thrombosis and pulmonary embolism dermatology acanthosis nigricans lymphedema cellulitis hirsutism intertrigo endocrinology and reproductive medicine diabetes mellitus polycystic ovarian syndrome menstrual disorders infertility complications during pregnancy birth defects intrauterine fetal death gastroenterology gastroesophageal reflux disease fatty liver disease cholelithiasis (gallstones) neurology stroke meralgia paresthetica migraines carpal tunnel syndrome dementia idiopathic intracranial hypertension multiple sclerosis oncology esophageal colorectal pancreatic gallbladder endometrial kidney leukemia hepatocellular carcinoma malignant melanoma psychiatry depression in women social stigmatization respirology obstructive sleep apnea obesity hypoventilation syndrome asthma increased complications during general anaesthesia increased risk of severe covid-19 rheumatology and orthopedics gout poor mobility osteoarthritis low back pain urology and nephrology erectile dysfunction urinary incontinence chronic renal failure hypogonadism buried penis metrics of health main article: metabolically healthy obesity newer research has focused on methods of identifying healthier obese people by clinicians, and not treating obese people as a monolithic group. 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. the number of people considered metabolically healthy depends on the definition used, and there is no universally accepted definition. there are numerous obese people who have relatively few metabolic abnormalities, and a minority of obese people have no medical complications. 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.: 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: bioshare healthy obese (hop) project criteria (2014)a patient must have a body mass index ≥ 30, and all of the following: less strict more strict blood pressure measured as follows, with no pharmaceutical help overall (mmhg) ≤ 140 ≤ 130 systolic (mmhg) n/a ≤ 85 diastolic (mmhg) ≤ 90 n/a blood sugar level measured as follows, with no pharmaceutical help blood glucose (mmol/l) ≤ 7.0 ≤ 6.1 triglycerides measured as follows,