Look at recent nonfiction hits on The New York Times Best-Sellers List, and you'll find the diet of the day, one in any number of "sure cures" for excess weight. Some promise rapid weight loss in a matter of weeks, and they do deliver -- temporarily. But many are downright unhealthy -- and because they're so difficult to follow over the long term, most people find that the weight comes back with a vengeance.

One weight-loss trend that's lasted through the decades is the high-protein diet. The concept was first introduced in the 1960s, and with the success of recently published guides by physicians such as Robert Atkins, the diets have made a resurgence. Atkins popularized the high-protein diet with his book Dr. Atkins' New Diet Revolution. Other programs, such as the Sugar Busters, Protein Power, and Stillman diets, also rely on adding protein to your regimen. Although some of these diets -- like Barry Sears' The Zone -- advise dieters to eat a diet low in fat, other high-protein diets rely on a high dose of both protein and animal fat.

Both types of diets carry some degree of risk, but the ones that draw the most controversy are high-protein diets that advise eating a lot of dairy products and unlimited quantities of red meat larded with saturated fats. According to the American Heart Association, diets high in both protein and fat can do serious harm to your health. Not only do they raise your risk of heart disease, but increase the likelihood that you'll develop diabetes, kidney disorders, and other serious illnesses, the association contends.

Two studies reported in the May 22, 2003 issue of the New England Journal of Medicine added fuel to the controversy. One study involved 132 patients at the Philadelphia Veterans Affairs Medical Center, about half on a low-carbohydrate plan, and the other on a low-fat diet. It showed that those who succeeded in following the low-carb plan for six months lost more weight than those who ate low-fat meals.

The other study involving 63 people specifically examined the Atkins diet, but it showed similar weight loss results. The Atkins dieters also raised their levels of HDL cholesterol, which helps prevent atherosclerosis. However, in both studies a little less than half of the original participants dropped out of the programs before the end of six months.

After a year, some of the Atkins dieters had regained up to a third of the pounds they lost, suggesting that long-term weight loss is difficult to maintain on these plans.

More recent large-scale studies continue to have contradictory findings. A 2006 Harvard study involving 82,802 women over 20 years found that low-carb, high-protein, high-fat diets do not increase coronary heart disease. Additionally the study discovered that a diet high in refined sugar is associated with an increased risk of heart disease and, confirming other studies, that consuming fat and protein from vegetable sources moderately reduces that risk.

However, two other large-scale studies published in 2007 – one involving over 22,000 adults in Greece and another 42,000 women in Sweden – have concluded that prolonged consumption of low-carb, high-protein diets correlates to increased mortality, particularly due to cardiovascular disease.

These plans claim to shave pounds by making your body burn fat. That process is jump-started by eliminating all or most carbohydrates, the foods your body uses to make sugar to feed cells. In most of these diets, protein makes up about 25 to 30 percent of the day's meals -- more than twice the amount of protein that non-dieters eat. The health hazards lie in what kind of protein you eat, doctors say.

If you were on Dr. Atkins' diet plan, for example, you could eat foods high in saturated fats, including eggs, bacon, butter, and poultry. If you were on the Sugar Busters diet, so-called "acceptable foods" would include such high-fat fare as butter and cheese, but you'd have to cut out anything made with white flour, sugar, and starchy vegetables such as corn. The Stillman diet allows you to eat all you want of lean meats, chicken, turkey, eggs, lean fish, and cottage and low-fat cheese until your hunger is satisfied.

Other high-protein eating plans, however, such as The Zone diet, advise people to avoid saturated fats and suggest eating low-fat protein such as white-meat chicken, fish, and vegetables.

Dieters lose weight for several reasons, not the least of which is that diets typically restrict calories to fewer than 2,000 a day. (That's roughly 700 fewer calories than in the typical American diet.) With fewer calories to use, your body is forced to look for other sources of fuel to burn. If you're not eating carbohydrates, your body breaks down fat cells. This breakdown of fat produces a buildup of toxic chemical compounds (ketones) in your blood. When there are too many ketones in your blood, your body eliminates them in your urine. Eliminate too many ketones, and you also eliminate too much water; without replacing it, you can suffer severe dehydration and the risk of abnormal heart rhythms. Since many of the diets eliminate fruit, vegetables, and whole-grain foods, and the fiber that goes along with them, dieters can also be prone to constipation.

Although you might lose weight initially, numerous studies have shown high-protein, high-fat plans to be ineffective over time, and they may in fact be harmful to your health. Most doctors and nutritionists agree that such plans keep you from getting essential nutrients, vitamins, and fiber found in plants, all of which help prevent disease and protect your health. Moreover, losing weight on this type of diet can lead to more serious health problems than being overweight, according to individual physicians and several leading US health organizations. A few of their findings:

"High-protein diets in their own right may [also] damage the kidneys, particularly if kidney disease is already present," says Robert Eckel, MD, a professor of medicine and physiology at the University of Colorado Health Sciences Center and one of the authors of an American Heart Association report on high-protein diets. When the AHA reviewed several popular high-protein weight-loss plans, it was especially harsh on those that had dieters eat high amounts of animal protein, saturated fats, and cholesterol. Forsake more healthful choices such as fruit and vegetables in favor of foods with higher levels of saturated fats, and your diet may lead to high blood pressure and heart disease, the AHA said.

The AHA's 2006 revised diet and lifestyle guidelines recommend limiting saturated fats to 7% of the diet and the AHA notes that a high protein diet makes that very difficult to accomplish. The Atkins diet, for example, allows 26 percent of your calories to come from heart-clogging saturated fat, and the Stillman diet and The Zone allow 13 and 9 percent saturated fat, respectively.

Although the AHA said all the diets would promote weight loss, the researchers pointed out that none of them was very practical, because they all limited food choices and were difficult to maintain over time.

The Atkins diet also received harsh criticism from researchers with the Nutrition Action Health Letter. When the group completed a nutritional analysis of weight-loss books in 2001, it judged the Atkins diet "unsafe" or "unacceptable" due to its high allowance of saturated fats. Nutrition Action gave Pritikin and The Zone high-protein diets a rating of "acceptable."

Holly Wyatt, MD, an assistant professor with the Center for Human Nutrition at the University of Colorado Health Sciences Center, believes many people succumb to the lure of high-protein plans because they believe they'll be able to eat fatty food without guilt.

"The diets allow unlimited quantities of low-carb, high-protein, high-fat foods, and Americans like large portions," Wyatt says. They also promote the idea that you can eat as much as you want of certain things, like hamburgers, and people find that appealing.

That was certainly the draw for high-protein dieter Jon Logan, who was on the Atkins plan for two years. The 47-year-old businessman grew up believing that a diet of fruits and vegetables was healthy, but the high-protein diet of steak, bacon, and eggs was irresistible: "We could eat eggs and cheese and bacon. That was breakfast," he says with satisfaction.

The Atkins plan advises dieters to take a host of nutritional supplements to replace the lack of variety in the regimen. Doctors also counsel dieters to drink 10 to 12 glasses of water daily to flush out the uric acid in meat that can cause gout. But many people on high-protein diets often forget to drink such large amounts.

Among them was Logan. Six months into the Atkins plan, Logan began experiencing excruciating pain in his right hand and foot, particularly in the big toe. "I could walk -- as long as I didn't walk in shoes," he recalls. A doctor determined that Logan, who lives in Berkeley, California, was suffering from gout. Logan immediately stopped eating organ meats, such as liver, sweetbreads, and other foods that produce high amounts of uric acid as waste, but he got a prescription to manage the agonizing pain so he could continue with the diet. He didn't stop the plan until he lost 20 pounds.

Proponents warn that high-protein plans are difficult to follow and that limiting carbohydrates is difficult for many people. Logan says he had strong cravings for bread, potatoes, and dessert. "You'd walk down the street and it was like the smell of bread baking everywhere. If I had one slice, I'd have the whole loaf," he says. Although Logan kept the weight off for two years after he went back to his normal diet, which included bread and pasta, he eventually gained 15 pounds back.

Some of the high-protein diets advise against excluding carbohydrates forever -- the Atkins diet, in fact, recommends that you increase your carbohydrate intake by 5 grams each week. However, weight gain is common among people who go back to their former eating patterns.

Wyatt says that's normal. "These diets do produce an initial, quick [mostly water] weight loss in the first several days, which encourages people to continue. When you start to eat carbohydrates again, this water will return."

Experts like La Puma advise people determined to try the Atkins diet or another high-protein plan to make the diets healthier by eating soy protein, fish, nuts, and olives rather than meats; avoiding saturated and trans fats; adding four low-carbohydrate fruits daily; and using supplements to provide missing vitamins and minerals.

The bottom line is that if you eat protein, it should be in a healthy form, without an overload of saturated fats. Vegetables and whole grains (complex carbohydrates), and water are a crucial part of any healthy diet. The key is to eat in moderation -- not taking in too many calories -- and to get exercise on a regular basis.

To lose weight, then, most people need to reduce calories -- if you cut out 250 calories a day, you're likely to lose one pound every two weeks. Start eating more, and you'll gain it back. Exercise regularly and your metabolic rate will increase, allowing you to burn more calories and helping you to avoid putting weight back on. Stop exercising, and the body will quickly put the weight back on.

This simple advice may not be the stuff of a best-seller, but it's much more likely to work.

-- Psyche Pascual is the articles editor of Consumer Health Interactive and a former reporter for the Los Angeles Times. Nina Silberstein is a freelance health and medical writer.

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First published June 26, 2002
Last updated November 30, 2007
Copyright © 2002 Consumer Health Interactive