Whenevermy patients bring up diet, they ask about fat. It’s an important topic becausetrans fats, high cholesterol, obesity, diabetes, and atherosclerosisall seem to go hand in hand. Dr. Atkins devotees say fat is fine; Dr. Ornishaficionados say it should be avoided at almost all costs. But a recent study bythe Women’s Health Initiative (WHI) suggests that thelink between dieting and fat intake may not be as strong as we think.
The WHI study was begun in 1993 with nearly 50,000women between the ages of 50 and 79 years. In one part of the WHI, half the women were asked to eat as usual andgiven generic diet-related education material. The other half were assigned tofollow a low-fat diet and participate in a variety of nutritional counselingsessions. The goal of the low-fat-diet group was to reduce their fat intakefrom 38% of calories to 20%. In reality, though, they only got it down to 29%. Afterfollowing these guidelines for eight years, researchers found that the women didnot have any additional protection against cancer or heart disease, and their weight was about thesame as those following their usualdiet.
What’s moststriking here is not the result, but the fact that even though these women agreed to participate in a study with agoal of 20% fat intake, and were given significant assistance, they were only able to bring it down to 29%. My patients'experiences, and I admit my own, support how difficult it is to control total fatintake. That’s why I encourage my patients to monitor what kinds of fats theyeat, not just how much fat. I recommend a diet low in saturated fat, trans fatand cholesterol.
It’s also importantto note that this study (like all studies) has some limitations:
• Thewomen were asked to self-report theirfat intake, and in many studies people have been shown to under-report their calorie and fat intake. (Just like the old commercial - when it comes to potato chips,most people can’t stop with just a few.)
• Another issue to consider is theage of the study population. Womenin the WHIwere between 50 and 79 years old. It is possible that by this time in a person’slife, a modest diet change over a relatively short period of time may not beenough to prevent disease. I would be interested in finding out if reducedrisks of heart disease, cancer, and otherchronic diseases would be more apparent through a longer study with a youngerpopulation.
Robert W. Lash, M.D. is an associate professor of internal medicine at the University of Michigan Medical School. His clinical interests include thyroid disease, diabetes, endocrine disorders in pregnancy, osteoporosis and metabolic bone disease, and medical education. A member of the LLuminari team of experts, a board certified internist and endocrinologist, Dr. Lash has an active clinical practice and is a hospitalist at the University of Michigan.