High-protein diets: where's the beef? - diets that discount carbohydrates in favor of high-protein diets can cause lose of needed water and other nutrients: includes a related article on 'The Zone' and other disputed diet books

Harvard Health Letter, Jan, 1997 by Eileen Norris

"Eating these carbohydrates could be dangerous to your health: bananas, cranberries, apple juice, orange juice, bagels, bread, carrots, cereal, popcorn, rice, potatoes, lima beans, and more." This is the alarm sounded by author Barry Sears, and it has been heard by hundreds of thousands of people who've shelled out $24 for his best-seller. The Zone.

Although this advice contradicts decades of nutritional wisdom, Dr. Sears is not alone in his crusade against carbohydrates. Dr. Atkins' New Diet Revolution, Michael and Mary Dan Eade's Protein Power, and Rachael and Richard Heller's Healthy for Life have collectively sold more than 1.5 million copies to a public fed up with being fat.

The popularity of these get-thin-quick schemes seriously disappoints nutrition researchers, who see them AS nothing more than reheated versions of the red meat and cream diets that were big in the early 1970s. Although they've been repackaged, these regimens have the same drawbacks as ever: people who follow them closely can lose an unhealthy amount of nutrients and water.

Dining in the Twilight Zone?

These diets generally urge people to eat a lot of protein-rich foods--such as steak and cheese--and to avoid rice, pasta, grains, and many fruits and vegetables. Although there are differences in the types of protein and the amount of fat each diet calls for the underlying theory is the same: carbohydrates--not just in pasta and bread but also in fruit--are to blame for most weight problems. The body turns carbs into glucose--that's certainly true. But the diet writers move onto shaky ground when they claim that most overweight people can't handle the resulting increase in blood sugar, and in response the body secretes "excess insulin" that somehow creates a craving for more carbohydrates. "Insulin is the hormone that makes you fat," Dr. Atkins asserts. The only way to escape this vicious cycle, he and the other authors say, is to seriously cut back on carbs.

Most mainstream researchers see these claims as science fiction. Eating anything causes blood sugar levels to rise, which in turn stimulates insulin production. This hormone ushers glucose into cells so it can be used for energy. An estimated one in four Americans is insulin resistant, meaning that their cells won't take up glucose unless an abnormally large amount of insulin is on hand. Most people develop this condition as a consequence of being overweight and sedentary--not because they eat too many carbohydrates. The good news is that insulin resistance, which sets the stage for diabetes and heart disease, can often be reversed by weight loss and exercise.

Calories do count

High-protein, low-carbohydrate diets cause people to lose their appetite; those who shed pounds on such regimens do so because they are eating so few calories. For example, the American Dietetic Association recommends that the average person--defined by the group as a 154-pound active male--consume a balanced diet of about 2,600 calories a day to stay healthy and fit. According to The Zone, a person who fits that description should eat about 900 calories daily.

Nearly everyone can lose weight by cutting back on calories--regardless of whether these come from fat, protein, or carbohydrates. But single-mindedly replacing carbs with slabs of meat could spell trouble for some people over the long haul. "The average American diet is not lacking in protein," said researcher Edward A. Mascioli, an assistant professor of medicine at Harvard Medical School. Most people eat 80-90 grams of protein every day, almost twice what they require. And foods rich in protein are often high in fat. Given this state of affairs, experts say there is no scientific justification for urging Americans to eat even more protein.

Over the past 25 years, numerous scientific studies have shown a link between high-protein, high-fat diets and serious health problems. This way of eating can raise cholesterol levels, promote the development of cardiovascular disease, and raise the risk for various cancers. In addition, some high-protein-diet mavens urge their followers to avoid foods with proven health benefits, such as fresh fruits and vegetables, grains, and low-fat dairy products. There is convincing evidence that a diet rich in these foods lowers the risk for heart disease, some types of cancer, osteoporosis, and cataracts. Such a regimen also helps people keep off the pounds they've lost.

Health claims are shaky

Those well-accepted medical facts are shrugged off by authors like Barry Sears, who claims that people who are "in the zone" will not only burn fat but also fight heart disease, diabetes, premenstrual syndrome, chronic fatigue, depression, and cancer.

The claim that a high-protein diet fights cancer appears ludicrous to Michael Thun, director of analytic epidemiology at the American Cancer Society (ACS). "I've seen no evidence that a high-protein diet protects against cancer," said Dr. Thun. "It's much better to adopt a steady diet that is high in fruits and vegetables, lower in fat, and possibly lower in protein."