Obesity is an excessive fat accumulation in the form of adipose tissue under the skin, within organs and muscles. In normal conditions the amount of body fat is 25 % for women and 15 % for men. Fat allows storing energy for future needs. However, significant fat deposition is associated with obesity problems. 1/4th of Americans fall under the category of obesity. The level of obesity may be evaluated with BMI - body mass index.

The correct regulation of food consumption may be affected by many causes such as genetics, hormones, metabolic activity, eating habits, and stressful factors. In obesity the body accumulates more food energy than is necessary for usual activity. From this standpoint, overeating and inactivity are the main causes of obesity. Family predisposition to obesity is extremely frequent. Particularities of child's feeding may play significant part in spreading of obesity from one generation to another. Lifestyle, emotional reactions and behavioral predilections may also contribute to obesity. Stress, fears and anxiety make some people recur to excessive eating to reduce tension.

Food intake control may be disturbed due to changes in hypothalamus and endocrine glands. Researchers also suggest that virus AD-36 may affect food assimilation and in this way increase the amount of body fat. It was also noticed that the digestive system of people suffering from obesity is populated by particular bacteria that are able to extract large amounts of calories from food.

For many people obesity is unwelcome from aesthetic point of view. Obesity is also a serious headache for health professionals. Life expectancy among obese people is shorter. Obese people are frequently ill and their diseases take more severe course. Obesity sufferers die prematurely of diabetes, heart disease, affections of blood vessels, stroke, and kidney problems. Obesity may affect mental health and patients give rise to wide range of behavioral symptoms from shyness to neuroses and psychoses.

The treatment of obesity is directed to elimination of causative factors and reducing food consumption.