Floridian: The skinny on high-protein, low-carbohydrate diets

Keeping Fit

The skinny on high-protein, low-carbohydrate diets

By PATRICK J. BIRD

Question: It seems that every other person I meet is on the Atkins Diet. Can you give me some information about this diet? And does it work?

Answer: The Dr. Atkins New Diet Revolution is not really new. Different versions have been around since the 1960s. This is a high-protein, very low-carbohydrate diet. At the most restrictive level, carbohydrates are limited to about 15 grams or less (i.e., an apple) a day. At the most liberal maintenance level, the daily carbohydrate allowance is no more than 90 grams (i.e., one bagel and one baked potato plus an apple). The remaining calories come from the unrestricted consumption of protein and fat. In addition, Atkins devotees are encouraged to take the nutritional supplements that he sells.

In contrast to the Atkins diet, the American Heart Association, the National Cholesterol Education Program and the American Cancer Society recommend that 60 percent of our calories should come from carbohydrates, 30 percent from fat and only 10 percent from protein. We are also encouraged to restrict our calories, if we are overweight, and to use food, not pills, to get our vitamins and minerals.

Atkins' diet overview. Here, in a nutshell, are the basic arguments Atkins makes for his diet and some criticisms of his ideas that have been raised over the last three decades:

-- Diets high in sugar, bread, pasta, cereal and other "low-fat," high-carbohydrate foods increase the production of insulin. Insulin, says Atkins, causes our bodies to store excess carbohydrates as fat. His diet, he says, limits the production of insulin and burns the fat placed in storage by this hormone. The criticism: Insulin moves glucose (carbohydrates) from the bloodstream to the body's cells. As such, this hormone is critical to releasing the energy we need to function. The notion that high insulin levels in some way conspire to make us fat, however, has not been substantiated by scientific research.

-- Eating a substantial amount of protein generates high levels of ketones. Ketones are chemicals produced by fat metabolism and, like the fat from which they are derived, they have calories. Atkins claims that the high production of ketones resulting from his diet can substantially contribute to weight loss since these chemicals are eliminated, along with their calories, in the urine. The criticism: There is little scientific evidence supporting the weight management significance of the increased levels of ketones. One estimate is that the calories eliminated by ketone excretion would at most amount to a weight loss of one pound a month.

-- Carbohydrates are less satisfying than protein and fat, Atkins says. So, we eat more carbohydrates and get hungrier faster when finished. The criticism: Even if this were proven to be correct, which it has not been, the wisdom of consuming high-protein products that often contain artery-clogging saturated fat and cholesterol is very questionable, if not outright dangerous.

-- Eating the Atkins way allows the body "to clean itself out," and this process may eliminate common ailments such as fatigue, depression, headache, joint and muscle pains, and will reduce high blood pressure and high cholesterol. The criticism: This is pure hype. There is little scientific evidence supporting this idea.

-- Finally, Atkins says his supplements provide "the answers" to such problems as constipation, sugar craving, fluid retention, nervousness, insomnia, hypertension, diabetes and arthritis. The criticism: Again, little or no evidence. In addition, concerns have been repeatedly raised about too much dietary protein resulting in calcium loss and about the contention by Atkins that his diet is actually not high in fat.

Hype and criticism aside. The fact is that people do lose significant weight on the Atkins diet. But this is mainly because they eat fewer calories and not because of some special magic in proteins. If you selected food choices with the highest calories from Atkins' "Typical Introduction Menu," for instance, you would likely consume no more than 1,500 calories for that day.

Also, although eating fewer calories primarily accounts for the diet's weight-reduction success, another important factor does come into play. That is water weight loss. And this can be particularly dramatic during the first few weeks on a high-protein diet. The reason is that when we eat carbohydrates, what is not immediately used for energy is stored in our cells as glycogen. And three to four grams of water are stored with each gram of glycogen. So, decreasing carbohydrates in our diets results in less water retention, or water weight loss. Also, high-protein diets tend to increase urination, further decreasing water weight.

End note. As a short-term approach to trimming down, the Dr. Atkins New Diet Revolution works, as do other high-protein diets such as Eades' Protein Power and Sears' The Zone. But adherence to any calorie-lowering effort will produce weight-loss outcomes similar to these diets -- and without the chancy metabolic changes associated with radical departures from generally accepted healthy nutrition. Moreover, limiting one's culinary life mainly to meat, fish, fowl and eggs would seem to be boring and very difficult to maintain. It should be kept in mind, too, that high-protein, low-carbohydrate diets are not, of course, for runners and other endurance athletes who rely on the glycogen from carbohydrates as their main source of fuel during exercise.

Patrick J. Bird, dean of the College of Health and Human Performance, University of Florida, draws on a data base of more than 3,800 medical, health and fitness journals in preparing answers to questions in his column. Write with questions to Dr. Bird, College of Health and Human Performance, University of Florida, Gainesville, FL 32611.