|Obesity is an excess of body fat frequently resulting in a significant impairment of health.
Adipose tissue is a normal constituent of the human body that serves the function of storing energy as fat. The fat may be used by the body in response to various metabolic demands. The excess fat accumulation is associated with increased fat cell size.A very important reason for obesity is the overconsumption of carbohydrates. When carbohydrates enter our body they are rapidly broken down into glucose (a sugar). Glucose raises blood sugar levels causing pancreas to make the hormone insulin. Insulin inhibits fat already stored in our body from being broken down and it also promotes the storage of new fat in the body; and increases cholesterol levels.In many forms of severe childhood-onset obesity, the total number of fat cells is increased.Formerly, obesity was explained by the single adverse behaviour of inappropriate eating in the setting of attractive foods. But now it has been established that obesity has multiple causes and is of different types. Both genetic and environmental factors are likely to be involved in the pathogenesis of obesity. These include excess caloric intake, decreased physical activity, and metabolic and endocrine abnormalities.Genetic determinants can either play a major role in the pathogenesis of obesity or enhance susceptibility to its development.The conditions in which genetics may play a role are Prader-Willi syndrome, Ahlstrom’s syndrome, the Laurence-Moon-Biedl syndrome, Cohen’s syndrome, and Carpenter’s syndrome.Over weight can be estimated by Body mass index (BMI), which is weight/height square, where weight is in kilograms and height is in meters.
Obesity is defined as a body mass index above 30 kg/square meter.
Weight gain may confer increased health risks even if the BMI does not exceed 25. In women a weight gain of more than 5 kg (11 lb) is associated with increased risks of diabetes and heart disease, and in men any weight gain after age 25 appears to carry increased health risks.