THE CAUSES OF OBESITY: GENETICS

Have you ever wondered why some of your friends can eat all day long without ever gaining a pound while you seem to gain weight just thinking about food? The reason, in part, may be an inborn propensity to either hold on to fat or to burn it. In recent years a great deal of research has been performed on the role of genetic factors in overweight conditions and obesity. The hormone leptin, for instance, seems to be tied to a specific gene and affects satiety, or the feeling of fullness that signals us to stop eating. Some people seem to be resistant to the effects of leptin, and there may be a genetic link here as well. Much is yet to be learned in this complex field, but scientists have associated several genes with such proclivities as the likelihood of gaining weight over time, the propensity for abdominal fat, and appetite control.

This is not to suggest that you adopt a fatalistic approach to controlling your weight. In most instances genetic factors depend on an environment conducive to their expression. While overweight parents commonly have overweight children, this is not due solely to genetics but to the way these children have learned to live. If you place these same children in different surroundings where they can learn better eating and exercise habits, chances are they will slim down. Consider youngsters who spend summers at weight-loss camps, where they become significantly thinner, but who start putting on the pounds again over the winter, when they are in less health-promoting home environments. Consider also countries where entire populations remained slim for thousands of years until fast-food diets began to replace the traditional style of eating. Now obesity is rampant in places where none was ever seen before. Obviously, the genetic makeup of the people did not suddenly change; rather, the environmental factors did.

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