The Diet Debate
Protein and carbs and fats, oh my! "Healthy" eating strategies inundate us these days, confusing even the savviest eaters with conflicting advice. "Cut out carbs," caution the protein proponents. "Limit proteins," suggests the carb-based USDA Food Guide Pyramid. Which plate promotes health—protein or pasta? Turns out both can when you make the right choices.
People tout high-protein diets for rapid weight loss, but heart health remains a concern with diets rich in animal protein. Duke University Medical Center researchers, funded by a grant from the Dr. Robert C. Atkins Foundation, conducted a six-month weight loss study involving 41 overweight or obese volunteers following the Atkins diet (American Journal of Medicine, 2002, vol. 113, no. 1). The researchers found that a diet restricted in carbohydrates—less than 25 grams per day—resulted in weight and fat loss and also improvement in cardiovascular-disease risk factors; in other words, "good"cholesterol levels increased, while "bad" cholesterol levels decreased.
High protein, low-carb diets are trendy, but is eating beef, bacon, and butter really healthy? The key to a healthy high-protein diet is choosing protein and fat sources wisely. "I don't think the usual form of these [high-protein] diets, which are high in red meat, butter, and other animal fats, is optimal for overall health because these foods have been associated with several cancers and are not optimal for heart-disease risk," says Walter C. Willett, MD, chairman of the department of nutrition, Harvard School of Public Health, and author of Eat, Drink, and Be Healthy (Simon and Schuster, 2001). "However, it is possible to have a very low-carbohydrate diet that is healthy if the fats are mainly vegetable oils and the protein sources are mainly fish, poultry, nuts, and legumes."
The argument for carbohydrates comes mainly from the USDA. Its Food Guide Pyramid promotes six to 11 daily servings of bread, cereal, rice, or pasta. This simple advice leads many people astray by not emphasizing the difference between types of carbs. You digest whole grains (brown rice and oats, for example) more slowly, meaning you feel full longer and don't suffer spikes in blood sugar levels triggered by refined carbohydrates (such as white rice, bread, pasta, and sweets)—plus whole grains provide fiber and more vitamins. "Whole-grain products ... do have positive health benefits for cardiovascular disease and diabetes," Willett says. But if the carbs are mainly refined starches and sugar, "high-carb diets definitely reduce HDL ["good"] cholesterol and increase triglycerides, and thus can increase heart-disease risk."
It comes down to smart choices. If you go protein, choose lean meats and plenty of plant proteins, such as nuts and beans. Can't resist the call of the carbohydrate? Find the least processed—whole-wheat bread and whole-wheat pasta, for example—and don't overdo it.