The reasons for obesity are multiple and complex. Despite conventional wisdom, it is not simply a result of overeating.
Research has shown that in many cases a significant, underlying cause of morbid obesity is genetic.
Research has shown that in many cases a significant, underlying cause of morbid obesity is genetic. Studies have demonstrated that once the problem is established, weight loss programs that use only dieting and exercise have a limited ability to provide effective long-term relief.

- genetics
- heredity
- environment
- metabolism
- eating disorders
- drugs (like steroids)
- medical conditions (like hypothyroidism).
Some genes determine eye color or height, other genes affect our appetite, our ability to feel full or satisfied, our metabolism, our fat-storing ability, and even our natural activity levels.
The body weight of adopted children shows no correlation with the body weight of their adoptive parents, who feed them and teach them how to eat. Their weight does have an 80 percent correlation with their genetic parents, whom they have never met.
Identical twins, with the same genes, show a much higher similarity of body weights than do fraternal twins, who have different genes. Certain groups of people, such as the Pima Indian tribe in Arizona, have a very high incidence of severe obesity. They also have significantly higher rates of diabetes and heart disease than other ethnic groups.
Fast food, long days sitting at a desk, and suburban neighborhoods that require cars all magnify hereditary factors such as metabolism and efficient fat storage.
For those suffering from morbid obesity, anything less than a total change in their environment usually results in failure to reach and maintain a healthy body weight.
Obesity researchers now talk about a theory called the "set point," a sort of thermostat in the brain that makes people resistant to either weight gain or loss. If you try to override the set point by drastically cutting your calorie intake, your brain responds by lowering metabolism and slowing activity. You then gain back any weight you lost.
That's why it's important that you work with your doctor to make sure you do not have a condition that should be treated with medication and counseling.