Q: What causes someone to become obese?
A: The core reason most people become overweight or obese is fairly simple: by taking in more calories than are burned on a daily basis. Those surplus calories will be converted into extra weight. The imbalance that leads to weight gain differs from one person to another due to pre-existing factors like genetics, health issues and mobility.
Think of your incoming and outgoing calories as a checking account that must be balanced. When you eat and drink, the food or beverage’s calories are “banked”. If you do not “spend” the calories efficiently, the excess is stored in your body as fat.
However, there are some factors in weight gain that we simply have no control over. Some illnesses may lead to weight gain, such as Cushing’s disease. Certain medications like steroids and antidepressants may also cause weight gain. There are also other underlying issues that often lead to weight gain, such as genetics, environmental factors, psychological issues, physical inactivity due to injury or illness, and eating disorders, such as BED (binge eating disorder).
Revision date: July 6, 2011
Last revised: by Andrew G. Epstein, M.D.