Generally, following factors are considered as leading cause for obesity:

eating more food than the body can use

inadequate physical activity or exercise 

It is also thought that genetic factors play a part in the development of obesity; children of obese parents are 10 times more likely to be obese than children with parents of normal weight. 

There may be other causes of obesity. This list is not all inclusive, and the causes are not presented in order of likelihood. The causes of this symptom can include unlikely diseases and medications. Furthermore, the causes may vary based on age and gender of the affected person, as well as on the specific characteristics of the symptom such as quality, time course, aggravating factors, relieving factors, and associated complaints. Use the Symptom Analysis option to explore the possible explanations for obesity, occurring alone or in combination with other problems.