Obesity is a condition in which excess body fat has accumulated to an extent that health may be negatively affected. It is commonly defined as a body mass index (BMI) of 30 kg/m2 or higher. This distinguishes it from being pre-obese or overweight as defined by a BMI of 25 kg/m2 but less than 30 kg/m2.
Excessive body weight is associated with various diseases, particularly cardiovascular diseases, diabetes mellitus type 2, obstructive sleep apnea, certain types of cancer, and osteoarthritis. As a result, obesity has been found to reduce life expectancy. A combination of excessive caloric intake, lack of physical activity, and genetic susceptibility is thought to explain most cases of obesity, with a limited number of cases due solely to genetics, medical reasons, or psychiatric illness.
The primary treatment for obesity is dieting and physical exercise. If this fails, anti-obesity drugs and (in severe cases) bariatric surgery can be tried.
As obesity is one of the leading preventable causes of death worldwide and with rates of adult and childhood obesity increasing, authorities view it as one of the most serious public health problem of the 21st century. Obesity is often stigmatized in the modern Western world. However, it has been perceived as a symbol of wealth and fertility at other times in history and still is in many parts of Africa.