High-fat diet boosts athletes' endurance


May 03, 1994|By Dr. Gabe Mirkin | Dr. Gabe Mirkin,United Feature Syndicate

Low-fat diets help to prevent heart attacks and certain types of cancers, but they certainly do not help to make you a better athlete. Studies in Sweden established the unquestioned dogma that a high-carbohydrate diet helps athletes to exercise longer. A recent paper from the State University of New York at Buffalo showed that a high-carbohydrate diet will not maximize endurance unless it also contains ample amounts of fat. Athletes on the high-fat diet with ample carbohydrates could run on a treadmill much longer than those on a high-carbohydrate low-fat diet or on a "normal" diet containing 61 percent carbohydrates, 24 percent fat and 14 percent protein.

It takes a lot of calories for athletes to train for many hours. How long you can exercise depends on how much sugar and fat you store in your muscles. When your muscles run out of their stored sugar and fat, they hurt, and you feel tired. Going on a low-fat diet causes you to take in fewer calories, you have less fat and carbohydrates in your muscles, you tire earlier and can't train as much. When it comes to training for endurance events, eat lots of fruits, vegetables, grains and beans for carbohydrates, but you should also take in ample sources of fat, such as vegetable oils and nuts or animal and diary fat.

Q: I compete very well in long-distance races, have small breasts and never wear a bra. My boyfriend wants me to wear a bra because he says that running without a bra will cause my breasts to sag. Who is right?

A: You are. There is no evidence that exercising without a bra causes breasts to sag. A breast is made up of skin on the outside, fat underneath and muscles under that. Breasts are held in place by skin and small ligaments that go from the skin to muscles underneath the breast. The intermittent stretching that occurs during exercise does not stretch out the skin or ligaments.

A breast is composed mostly of fat, so when a woman starts to exercise, she loses fat from her breast and they become smaller and may appear to sag. Some women may need support to feel more comfortable. If a woman wants to wear a bra, she should choose one that is loose enough to let her breathe comfortably, and tight enough to keep the breasts from bouncing and the bra from riding up or twisting during exercise.

Q: My boyfriend takes many vitamin pills and wants me to do the same. Is there any evidence that taking large doses of vitamin pills will harm me?

A: Yes. A 10-year study from Finland came to the astonishing conclusion that beta carotene, a vitamin A analog, contributes to lung cancer. For more than 50 years, scientists have thought that beta carotene prevents cancer. Scientists in Finland followed 30,000 male cigarette smokers for 10 years. Those who took vitamin E had the same incidence of lung cancer as those who didn't, but those who took beta carotene had an 18 percent higher incidence of lung cancer.

Scientists have extracted hundreds of chemicals from foods and have shown that some help prevent cancer while others help cause it. Vitamin A, C and E, the mineral, selenium, and other chemicals such as sulforaphane, rutin and ubiquinone, help to prevent cancer. However, the studies evaluate chemicals out of food and do not really evaluate the total effect of the food themselves.

The data clearly show that eating a low-fat, high-fiber diet helps to prevent some cancers and that taking vitamin pills has not been shown to protect you from an unhealthful diet.

Dr. Mirkin is a practicing physician in Silver Spring specializing in sports medicine and nutrition.

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