Oct. 8, 2001 -- High-protein diets -- The Atkins Diet, The Zone, Sugar Busters, Stillman, and Protein Power -- are very popular. But they may be risky to long-term health, according to a new advisory from the American Heart Association's nutrition committee.
The basic premise of these diets is that people can eat all types of proteins but must restrict -- and sometimes eliminate -- other foods, especially carbohydrates like cereals, grains, fruits, vegetables, as well as milk products. The diets have been around for years but have faded in and out of popularity.
"The concern is that people on these diets eat more saturated fat and cholesterol but get very few of the essential vitamins, minerals, fiber, and other nutritional elements in carbohydrates," says Alice Lichtenstein, DSc, a professor of nutrition at Tufts University and vice chairwoman of the nutrition committee of the American Heart Association (AHA).
"There are no long-term studies of these high-protein diets," she tells WebMD. However, scientific evidence suggests that the diets carry "great potential" risk of heart disease as well as problems for the kidneys, bones, and liver, she says.
In its study, the AHA committee looked at each diet's philosophies, including foods to eat and avoid, diet composition, recommended supplements, health claims, and the practicality of each diet. They also assessed the diets' ability to help people lose weight and maintain that loss.
Researchers found that the high-protein diets run counter to guidelines set by every major health organization in the country, Lichtenstein tells WebMD. These groups include the American Dietetic Association, American Cancer Society, and the National Institutes of Health.
All the diets recommend excessive protein, which often leads to too much total fat and saturated fat, says the AHA study. The Zone and Sugar Busters omitted or severely restricted carbohydrates. All the diets were deemed as unsafe over the long term because they do not provide adequate nutrition or support healthful eating.
The following are some of the health risks of high-protein diets, according to the experts:
- They may increase LDL, or the level of "bad" cholesterol, since a diet rich in animal protein often contains saturated fat and cholesterol. That effect is compounded when high-carbohydrate, high-fiber plant foods -- which naturally help lower cholesterol -- are limited or eliminated.
- They may increase blood pressure, since fruits, vegetables, low-fat dairy products, and whole grains have been shown to lower blood pressure.
- They may promote bone-thinning osteoporosis, since excess protein in the diet triggers the body to excrete calcium during urination.