A RECENT nutrition study noted that 50 percent of all people who diet do not need to, while 80 percent of the people who should be dieting are not. Many medical experts say that a person's body shape, rather than weight, is the indicator of health risk.They note that the bulges at a woman's hips and thighs are usually far less hazardous than the spare tire carried around the waist of her male counterpart.
Dr. Marielle Rebuffe-Scrive, a biochemist, has spent 16 years in France and Sweden studying lipid metabolism and the factors that regulate distribution of fat to different regions of the body, particularly the effect of hormones on this process.
In a rare collaboration between the natural and social sciences, Dr. Rebuffe-Scrive came to Yale University's department of psychology three years ago on a MacArthur Foundation fellowship to expand her research to include behavior as a factor in assessing the relationship between hormones, body fat distribution and health consequences.
In a recent interview at her office in Dunham Laboratory at Yale, Dr. Rebuffe-Scrive talked about her work. Here are some excerpts from the conversation.
Q. How does one's body shape relate to health and well-being?
A. In 1947 a French colleague of mine, Prof. Jean Vague, noticed a difference in the rates of different diseases according to body shape. Renewed interest in this theory came about 10 years ago, when a number of epidemiological studies showed a statistical association between fat localized in the central part of the body, the abdominal region, and increased risk factors for cardiovascular disease and diabetes. The studies found no such association with fat distributed in the lower part of the body. This gave us only the association, not the causal relationship. Then you have to find all the factors involved.
Q. What are some of the factors?
A. Genetics, of course, plays a part, about 30 percent, in determining a person's body shape. Hormones, including sex hormones and corticosteroids, also seem to affect where we accumulate fat. A number of environmental factors, too, including smoking, alcohol ingestion, stress and dieting behavior, seem to be associated with increased abdominal fat accumulation. For instance, one Swedish study that compared heavy alcoholic drinkers with non-drinkers found that the heavy drinkers had two to three times the amount of intra-abdominal fat.
Q. What are the two basic body shapes and how does one determine which category one belongs to?
A. Sometimes described in the media as apples and pears, the actual terms are android, for the abdominal type of fat distribution, and gynoid, for the hip and thigh fat distribution. There is a very simple index that is used to measure a person's fat distribution, called the waist-to-hip ratio, or W.H.R.
Using a tape measure at defined points, we take the waist circumference and the hip circumference. Androids, or apples, have a high waist-to-hip circumference ratio, while gynoids, or pears, have a low W.H.R. Generally, men have more fat in the abdominal region while the other type of fat distribution is more typical in females. This is what led us to research whether or not sex hormones had anything to do with it.
Q. Are the two categories split mainly along gender lines?
A. No, there are a few men who have the gynoid type of fat distribution, and there are a lot of women who have the android, or male, type of fat distribution. About 22 percent of pre-menopausal women fit in this category, but this figure increases when post-menopausal women are included. It has been shown that women who have the android shape generally have less female hormones than others and have a slightly elevated level of male hormones.
It is very, very slight, though, and has nothing to do with the serum concentration of sex hormones in men. What is very interesting is that android women also have increased risk factors for cardiovascular disease and diabetes.
Q. Is the increased risk present only in overweight people?
A. Yes and no. You need to add obesity to really have the disease, but a man who is very slim and has a big stomach has more of a risk than a man who is obese everywhere. Simply put, excessive fat in the abdominal region is associated with risk, but the risk is increased with obesity.
Q. How do the sex hormones affect the way the body distributes fat?
A. The female sex hormones, estrogen and progesterone, tend to favor fat accumulation in the lower part of the body, the thighs and buttocks. This fat is very difficult to burn. During pregnancy, this phenomenon is even more pronounced. During lactation, however, fat no longer accumulates preferentially in the lower part of the body and is more easily mobilized. It seems that the lower body fat is some sort of reserve of energy that women need for lactation, and that only women have fat in this region to serve a typical female function, breast feeding.
Q. What happens after menopause?
A. After menopause, when they are not producing sex hormones, women no longer preferentially accumulate fat in the lower region but tend to increase fat accumulation around the abdomen. However, post-menopausal women on estrogen and progesterone replacement therapy tend to accumulate fat in the lower body region like young, fertile women.
Q. What can women do to counteract the tendency after menopause to gain weight around the middle?
A. You cannot do very much. In practical terms, though, there is very good advice here. It makes good sense to breast feed your child, and also, as you approach menopause, watch your body by being careful what you eat, exercise, and try not to gain weight because it will tend to go into that region.
Q. What about men?
A. When men get older, they also produce less sex hormones. We have shown, though, that in middle-aged men who had their testosterone levels increased by pill therapy, there are two factors that work: the enzyme which controls fat accumulation in the abdominal region is repressed; furthermore, fat mobilization is increased. These findings suggest that as men get older, and they produce less testosterone, it becomes more difficult for them to burn abdominal fat. Therefore, it becomes easier for them to accumulate fat in that region.
Q. Why do men seem to lose weight more easily than women?
A. Thigh and rump fat in women is very stable. It goes in quite easily but is very difficult to lose. In men, abdominal fat may accumulate, but it is burned more easily. That is why a man may have a fat stomach, but he can lose it more quickly.
An important point, though, is that while we are concerned about the fat we see, subcutaneous fat, we are more concerned about the amount of intra-abdominal fat that is found around the organs.
The increased risk factors for cardiovascular disease and diabetes is even more pronounced when correlated with the amount of intra-abdominal fat. The order of correlation for disease would be first, intra-abdominal fat, then, subcutaneous abdominal fat.
Q. How is one to know if you have intra-abdominal fat?
A. There are some new, sophisticated tests, but they are very expensive and not commonly used. It is not necessary for everyone to know exactly how much intra-abdominal fat they have, but it is important to know that fat accumulates internally as well as subcutaneously, and that might have unwanted health consequences. I am struck by the number of men I see on the street with such large stomachs who probably are not aware of this.
Photo: Dr. Marielle Rebuffe-Scrive, a biochemist, is conducting research at Yale University. (Bill Burkhart for The New York Times)
Limauro, Mary Ann. "Connecticut Q&A: Dr. Marielle Rebuffe-Scrive; Health, Hormones, Body Shape and Fat.(Connecticut Weekly Desk)(Interview)." New York Times 22 Sept. 1991. Academic OneFile. Web. 4 Dec. 2009.
Gale Document Number:A175323007
Disclaimer:This information is not a tool for self-diagnosis or a substitute for professional care.
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