World Health Organisation classifies obesity as a disease, though many consider it as a self-inflicted problem. However, the outcomes of obesity like cancer, arthritis, joint pain, sleep apnoea, are definitely diseases.

More than 200 gene variations influence weight and those that increase weight are more common in people with severe obesity and less likely to be found in people who are thin. Most of these genes in the brain affect the appetite control of the person.

However, researchers believe the recent rapid increase in obesity is not because of genetics, but because of an environment that encourages weight gain like food availability, cost of food and social deprivation.