| Obesity | |
|---|---|
| Silhouettes and waist circumferences representing optimal, overweight, and obese | |
| Classification and external resources | |
| Specialty | Endocrinology |
| ICD-10 | E66 |
| ICD-9-CM | 278 |
| OMIM | 601665 |
| DiseasesDB | 9099 |
| MedlinePlus | 007297 |
| eMedicine | med/1653 |
| MeSH | C23.888.144.699.500 |
Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have a negative effect on health. People are generally considered obese when their body mass index (BMI), a measurement obtained by dividing a person's weight by the square of the person's height, is over 30 kg/m2, with the range 25–30 kg/m2 defined as overweight. Some East Asian countries use lower values. Obesity increases the likelihood of various diseases, particularly heart disease, type 2 diabetes, obstructive sleep apnea, certain types of cancer, and osteoarthritis.
Obesity is most commonly caused by a combination of excessive food intake, lack of physical activity, and genetic susceptibility. A few cases are caused primarily by genes, endocrine disorders, medications, or mental illness. The view that obese people eat little yet gain weight due to a slow metabolism is not generally supported. On average, obese people have a greater energy expenditure than their thin counterparts due to the energy required to maintain an increased body mass.