Millions of people who have tried again and again to diet, but there are elements of it that particularly intrigue medical researchers who are beginning to uncover the mystery of why some people are overweight-and why repeated dieting may actually make it harder to lose weight. The new research cannot yet promise cures for obesity or overeating, but scientists are hopeful that these studies will eventually lead to a treatment. Fat cells grow to four to five times their normal size. We can push the fat-cell size in any animal to a bare minimum by depriving it of food. But if we leave an animal or a person alone, the fat cells will stay constant in size This suggests that there are regulating signals between the fat tissue and the central nervous system” In very obese people, whose fat cells are two-and-a-half times larger those of normal people, these signals may be disrupted.
A group of people who belong to overeaters anonymous, all are of normal weight, but each was formerly very obese. While they all look normal, however, their body chemistries are deranged. Their fat cells are tiny, similar to those in people with anorexia nervosa, their pulse rates and blood pressures are low.
A method for measuring the propensity of fat cells, to accumulate fat, or to break it down, and in so doing he came upon an intriguing result. People who can not spot-reduce –women, for example, who can not get rid of their large hips-may have fat cells in their problem areas that simply will not release fat.
Fat cells on women’s hips and thighs tend to have predominantly alpha receptors, which means they tend to hold on to fat. Among the Rockefeller University patients, one pear-shaped woman who had lost 20 pounds looked worse than when she began her dieting. The fat cells on her hips and thighs contained mostly alpha receptors and released very little fat as she lost weight else where.
Since most overweight people diet not once but and over again, investigators are beginning to wonder whether dieting itself can be self-defeating.
Do these findings hold true for humans, a metabolic ward, in which very obese people lose weight on a carefully controlled, very low-calorie diet. A number of patients return to the ward three times, even five times, to lose weight. And each time they come, they lose weight more slowly than they did the previous time. These people, like the laboratory rats, have apparently learned to be very efficient users of food as a result of yo-yo dieting.
The common theme emerging from these laboratories and hospitals in clear: the fat cell is a major culprit. Researchers can not yet say why some people have more of these cells than others do, or where they come from. But scientists hope that, when they gain a better under standing of these cells, the signals to overeat may be circumvented.
At least, the very fact that researchers are looking seriously at the biochemical basis of obesity is comforting
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