Obesity

Obesity
Silhouettes and waist circumferences representing normal, overweight, and obese

Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have a negative effect on health, leading to reduced life expectancy and/or increased health problems.^[1][2] In Western countries, people are considered obese when their body mass index (BMI),^[3] a measurement obtained by dividing a person's weight by the square of the person's height, exceeds30 kg/m², with the range 25-30 kg/m² defined as overweight. Some East Asian countries use stricter criteria.

Obesity increases the likelihood of various diseases, particularly heart disease, type 2 diabetes, obstructive sleep apnea, certain types of cancer, and osteoarthritis.^[2] Obesity is most commonly caused by a combination of excessive food energy intake, lack of physical activity, and genetic susceptibility, although a few cases are caused primarily by genes, endocrine disorders, medications, orpsychiatric illness. Evidence to support the view that some obese people eat little yet gain weight due to a slow metabolism is limited. On average, obese people have a greater energy expenditure than their thin counterparts due to the energy required to maintain an increased body mass.^[4][5]

Dieting and exercising are the main treatments for obesity. Diet quality can be improved by reducing the consumption of energy-dense foods, such as those high in fat and sugars, and by increasing the intake of dietary fiber. With a suitable diet, anti-obesity drugs may be taken to reduce appetite or decrease fat absorption. If diet, exercise, and medication are not effective, a gastric balloon may assist with weight loss, or surgery may be performed to reduce stomach volume and/or bowel length, leading to feeling full earlier and a reduced ability to absorb nutrients from food.^[6][7]

Obesity is a leading preventable cause of death worldwide, with increasing rates in adults and children. Authorities view it as one of the most serious public health problems of the 21st century.^[8] Obesity is stigmatized in much of the modern world (particularly in theWestern world), though it was widely seen as a symbol of wealth and fertility at other times in history and still is in some parts of the world.^[2][9] In 2013, the American Medical Association classified obesity as a disease.^[10][11]