Genes and the Environment of Night Eating Syndrome

Does the fact that a defective ob/ob gene is only a very rare cause of human obesity mean that genetics plays almost no role in obesity? The answer is no. The study of twins introduced by Galton 150 years ago helped scientists to estimate the extent of genetic influences on a wide variety of human diseases. Among these conditions, obesity probably has one of the largest genetic contributions. When Swedish twins who were separated at birth, and thus had no environmental influences in common, were studied, it was estimated that 70 percent of their body weight was genetically determined (Stunkard et al. 1990).

Obesity and overweight are rapidly increasing in the American population and now affect 65 percent of the adult population (Flegal et al. 2002), so detecting and countering the contributing genetic factors is an important challenge. Yet, you must be well aware that heredity is not the only factor that causes obesity. In many health conditions, genes are only one part of the cause. The other is environment, which brings us to the idea of gene-by-environment interactions.

Genes completely determine the color of eyes and hair. The environment has no effect, and thus for hair and eye color there is no gene-by-environment interaction. Heredity, however, does not completely determine human behavior; the environment also exerts an important influence. The 70 percent genetic influence on body weight means only that some people are very vulnerable to becoming obese. They, like you, do not become obese in a vacuum, however.

To become obese, you must consume more calories than you expend. If you do not have a genetic vulnerability to obesity, it is likely that you will not overeat and become obese. The converse, of course, is also true. If you do have a genetic vulnerability, it is more likely that you will overeat and become obese.

All human behavior is determined by this interaction between genes and environment. This gene-by-environment interaction is as true of Night Eating Syndrome as of obesity or any of the behavioral disorders that afflict us. Given this understanding, let us turn to what we have learned about genetic influences on Night Eating Syndrome.

Related posts:

1. The Genetics of Night Eating Syndrome
2. Night Eating Syndrome and Your Health
3. Medical Complications of Night Eating Syndrome Caused by Obesity
4. What Night Eating Syndrome Is Not?
5. Do biological factors contribute to eating disorders?
6. Sleep Apnea and Night Eating Syndrome
7. Binge-Eating Disorder and Night Eating Syndrome
8. Night Eating Syndrome and Polysomnography
9. Dieting and Night Eating Syndrome
10. Night Eating Syndrome – Getting Help from Others