Obesity

Obesity
Silhouettes and waist circumferences representing optimal, overweight, and obese
Specialty	Endocrinology
Symptoms	Increased fat[1]
Complications	Cardiovascular diseases, type 2 diabetes, obstructive sleep apnea, certain types of cancer, osteoarthritis, depression[2][3]
Causes	Excessive 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, genetics[1][4]
Diagnostic method	BMI > 30 kg/m2[1]
Prevention	Societal changes, changes in the food industry, access to a healthy lifestyle, personal choices[1]
Treatment	Diet, exercise, medications, surgery[5][6]
Prognosis	Reduced life expectancy[2]
Frequency	Over 1 billion / 12.5% (2022)[7]
Deaths	2.8 million people per year

Obesity is a medical condition, considered by multiple organizations to be 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/m²; the range 25–30 kg/m² 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, low physical activity, automation, urbanization, genetic susceptibility, medications, mental disorders, economic policies, endocrine disorders, and exposure to endocrine-disrupting chemicals.^{[1][4][14][15]}

While 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. The World Health Organization stresses that the disease is 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]}