The popularity of low-carbohydrate, high-protein diets is at an all-time high, thanks to a number of best-selling books. Among them is Protein Power, which graced the New York Times best-seller list for over a year, sparking controversy with its assertion that the mainly carbohydrate-based diet --fruits, vegetables, and starches -- is responsible for rampant obesity and heart disease, not the traditionally named culprits such as red meat, eggs, and dairy products.
Written by a married couple of MDs, Michael R. and Mary Dan Eades, the book promises that you will "feel fit and boost your health -- in just weeks!" The cover includes praise from one of their diet-expert-author competitors, Barry Sears, author of The Zone, who calls their book nothing less than "The Nutritional Primer of the Nineties."
What sets Protein Power apart is the wealth of historical information about low-carbohydrate diets and how these have influenced dieters galore, ever since William Banting wrote his Letter on Corpulence in the mid 1800s. The Eades also provide scientific explanations for the functions of insulin and glucagons, the major hormones involved in the food-to-fuel process, along with plenty of encouragement and practical suggestions, such as what to order in a French restaurant or fast food joint.
Those of you who crave steak, eggs, and cheese will have a great time on this diet. Vegetarians will not, because tofu is the main source of protein allowed non-meat eaters. And as even the most dedicated know, tofu three times a day can get tiresome.
To determine your daily protein quotient, the authors take you through a series of steps and measurements to determine your body fat and lean body mass, as well as ask you to assess your physical activity level.
You may choose your protein from fish, poultry, red meat, low-fat cheese (cottage cheese, feta, mozzarella, Muenster), eggs, and tofu. If you want to lose a lot of fat (the authors don't say you lose weight, but fat instead) or correct a health problem, you can add only 30 grams of carbohydrate, or less, divided throughout the day. If your need to lose is not so great, you can up that quota to 55 grams per day. Favorite low-carb foods? Lists of low-carb fruits and vegetables are given to make your life easier. These include leafy green vegetables, tomatoes, peppers, broccoli, eggplant, zucchini, green beans, asparagus, celery, cucumber, mushrooms, and a surprise fruit that rarely makes the diet sweepstakes: avocado, high in fat, but low in carbs.
Add in 25 grams of fiber (you can subtract the fiber grams from the carbohydrate grams in commercially processed foods, which gives you more carbs to play with), and healthy fats: olive and nut oils, avocado, and butter. Drink at least eight glasses of water per day. And a glass of wine or a light beer is OK, but their carbs count, too.
The book's sample menus don't sound too temperate: Breakfast might be smoked salmon and a cream cheese omelet, one-half cup of fresh strawberries, a slice of light toast with butter, and coffee; for lunch, one-half avocado stuffed with chicken salad made with mayonnaise, served on a bed of fresh greens. Dinner might be a lean cut of meat, ten steamed asparagus spears, salad, one-half tomato, and a small glass of red wine if desired. Diet sodas and artificial sweeteners are permitted in moderation.
To round out nutritional needs, the authors recommend taking a high-quality vitamin-and-mineral supplement, along with at least 90 milligrams of potassium.
The book contains sample menus, more than 100 recipes, and suggestions on how to order in every kind of restaurant.
Like the other low-carbohydrate diets, the Protein Power regimen is based on the idea that controlling the level of insulin, "the master hormone of human metabolism," helps regulate blood pressure, cholesterol, triglycerides, and fat storage. Researchers have long known that carbohydrates cause the body to produce insulin and that high levels of insulin inhibit the breakdown of fatty deposits in the body. In contrast, low intake of carbohydrates keeps insulin levels low, forcing the production of a counterbalancing hormone, glucagon, which seeks energy from the body's supply of stored fat. Ergo, one loses weight. Do this long enough and the fat seems to melt away, the authors claim, and they add that the usual "low-fat, high-carbohydrate approach won't do it; it has just the opposite effect."
If you are very overweight, the initial phase of the diet (when carbohydrates are severely restricted) will almost certainly put you in a state of ketosis, which happens when fat breaks down to the point where ketone bodies are produced and excreted in the urine. Ketones are incompletely burned fat, say the Eades, so that any ketones "you get rid of without actually using them for energy means you are ditching unwanted fat without having to actually burn it off."
Is ketosis dangerous, as some nutritional authorities would have you believe? Not at all, attest the authors. Ketones are the natural by-product of fat breakdown, normal and important sources of energy. To facilitate getting rid of these ketones, they urge you to increase your fluid intake by as much as 50%, to at least two quarts of water-based fluids a day.
As for exercise, the authors favor resistance-training, such as weight lifting, because it stimulates the release of growth hormone more quickly than aerobic exercise. Why is this important? Because growth hormone shifts the metabolism to the preferential use of stored fat for energy.
Low-carbohydrate diets, which always mean high protein, almost universally draw a red flag from conventional nutritionists and medical experts. But since they do jump-start weight loss that you can see quickly, some say they have their place. "Fad diets are OK for a quick start," notes Bonnie Brehm, PhD, assistant professor of nutrition at the University of Cincinnati's College of Allied Health Sciences in Cincinnati, Ohio. "Some people need to see that five-pound weight loss rather than just a single pound after a week of dieting." Brehm is conducting a study comparing a high protein diet with the low-fat diet recommended by the American Heart Association.
"In the short term, the low-carb diets are effective -- we see weight loss, improvement in some metabolic functions such as blood pressure, loss of body fat, but their real hazard is that they are nutritionally poor," she says. "They are low in calcium, low in vitamins C and A, low in fiber. We don't know if taking a vitamin-mineral supplement is adequate. There are a lot of micronutrients in foods that are not in supplements, including some we don't even know about yet. We do not have any long-term studies on these alternative diets with the extreme modifications of a nutritionally balanced diet."
Susan B. Roberts, PhD, a professor of nutrition and psychiatry at Tufts University in Boston, Mass., and co-author of Feeding Your Child for Lifelong Health, does not recommend the diet because there is no good evidence that low-carbohydrate diets work any more effectively than conventional ones. Furthermore, she says, "Because they cut back on foods that have multiple health benefits, they may reduce health in the long term."
Roberts notes that the Protein Power regimen may work for many, but the reason is different from the theory put forth in the book. It simply may be the lack of variety that works to reduce overall calorie intake. "Protein Power and most other popular diet books substantially reduce the variety of foods you are allowed to eat -- and variety itself is a major promoter of overeating," she says.
As with any of the currently popular low-carbohydrate and high-protein diets, this plan yields weight loss on the short term. However, the established nutritional community warns that these eating plans can be seriously deficient in important nutrients. While this plan does offer a range of sample diets and menus, it requires a reduction in the variety of foods that one can eat, which may be difficult to sustain over the long term.
Reviewed By Charlotte E. Grayson, MD February 2004.
SOURCES: Eades, M. Protein Power, 1998, Bantam Books. Bonnie Brehm, PhD, assistant professor of nutrition, the University of Cincinnati's College of Allied Health Sciences, Cincinnati. Susan B. Roberts, PhD, professor of nutrition and psychiatry, Tufts University, Boston.
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