Weight Loss 201: The Atkins Diet–Do Calories Count?
The meaning of the word diet, daily fare, has edged into extenuation, and is now defined in Webster's second definition as special or limited selection of food and drink chosen or prescribed for health or to gain or lose weight. But the D-word is beginning to sound more like Webster's first definition from the Greek, dieta, meaning literally "way of life."
The three chemical classes of food from which we derive our energy in the form of calories are carbohydrates (4 Calories per gram), fats (9 Calories per gram), and protein (4 calories per gram). Carbohydrates include simple sugars and long chains of linked simple sugars called complex carbohydrates or starches, usually derived from cereal grains, such as rice, wheat, oats, from which we make our breads, pastas, cakes, etc. Fats include those of animal origin and liquid fats or oils, usually plant-derived. Proteins are enormous chains of linked units called amino acids. Humans and non-herbivorous animals require for survival all three components, carbohydrates, fats, and protein.
The diet controversy becomes complicated when we talk, not principally about calories per se, but focus on diet composition, the percentages of calories derived from carbohydrate, fat, and protein. (Foods also contain widely varying amounts of water, fiber, vitamins, minerals, and other components.) Since all complex carbohydrates contain some protein, and the so-called protein-rich foods, such as meat, fish, eggs, dairy products, etc. contain varying amounts and types of fat as well as carbohydrates, it became necessary to create some classification scheme identifying the type of food, hence the development of food groups and the USDA Food Pyramid, developed in 1977 and revised in 1991. As Dr. Walter Willet, Chairman of the Nutrition Department at Harvard observes, "The food guide pyramid that was developed in 1991 really is based on the idea that all fat is bad. Therefore [if] fat is bad and you have to eat something, carbohydrate must be wonderful. So the base of the pyramid is really emphasizing large amounts of starch in the diet."
Along came the Atkins diet, attacked in 1973 by the AMA, which turns the food pyramid on its head by putting protein-rich foods such as meat on the bottom, and "whole grain foods" on top. In effect the "low carb" diet is high protein, high fat. Only about 20% of calories are derived from carbohydrates 23% from saturated fat, and 36% from protein. The USDA diet allows about 40% of calories from carbohydrate, while the American Heart Association Diet allows 55% of calories for carbohydrates and only 15% from protein. Other diets, particularly weight loss diets with different percentages of calories derived from carbohydrate, fat, and protein respectively, form an almost endless list going back long before Atkins and the USDA's food pyramid came of age in the 70s.
Dietary strategies for health and/or weight loss ultimately resolve into the questions: what counts, calories, dietary composition, or both? This is where the problem becomes irresolvable. Despite the virtual impossibility of controlled experiments with dietary manipulation in any given population of thousands of subjects, the dietary advice literature continues to explode.
A superb review written by Kathy Goodwin, a registered dietition for The Diet Channel, discusses what she calls "Insulin Insanity" in connection with theories about low carbohydrate diets.
Goodwin writes, "Insulin helps the body store fat. Because of this fat-storing function, low carb plans have condemned insulin to eternal damnation. Unfortunately, [this is] based on false and twisted truths. One false theory is that only carbohydrate in the diet will stimulate insulin production. The truth is that all ingested foods stimulate insulin production. The second false theory is that insulin stores fat only when high carb foods are eaten. The bottom line with regard to the body's biochemistry is that fat will only be stored if too much food (from any source) is eaten." My emphasis.
The Danish investigator, Professor Astrup analyzed the Atkins diet and assorted claims that low carbohydrate diets are effective for weight loss. In Astrup's article, one of the best and latest on the subject appearing in The Lancet 2004; 364:897, he and his colleagues examined 2,609 articles on low carbohydrate diets, and found out of only 107 articles which could be reviewed. "Only five studies evaluated participants for more than 90 days, but were not randomized and had no control group. There was insufficient evidence to make recommendations for or against these types of diets." In 2003 three randomized trials reported the longer-term effects of low carbohydrate diets. In the first study with 132 obese subjects given an all-you-can-eat low carbohydrate or energy-restricted low fat diet for a year and controls, those on the low-carbohydrate diet lost 3-12 pounds after 6 months, but at 12 months the differences were no longer significant. The third study produced similar results (total 53 patients). The second trial did show some comparative weight loss in 26 patients in the low carbohydrate group, but lasted only 6 months. Note the low number of subjects in all these studies. (Also see http://www.4woman.gov/news/julsep04/sep35.htm)
Is the Atkins diet safe? According to Astrup, "…restricted intake of whole grain bread and cereals, fruits and vegetables does not equal a healthy diet, and absence of these food groups may increase the risk of cancer and cardiovascular disease." Moreover, the low carbohydrate contents of the diet is "below the minimum needed to supply the brain and muscles with sugar." Atkins dieters more often report muscle cramps, diarrhea, halitosis (bad breath), general weakness, and rashes than those on a recommended low fat diet. In summary Professor Astrup and colleagues conclude there is a need for longer (up to 2 years) studies to assess the weight loss efficacy of low carbohydrate diets. They recommend that people who want to lose weight and keep it off should eat a diet reduced in calories and fat, and increase physical activity. (Contact: Professor A. Astrup, Department of Human Nutrition, Centre of Advanced Food Research, RVA University, 1958 Frederiksberg C, Copenhagen, Denmark;E) ast.kvl.dk
The bottom line: Atkins probably works for a little while (up to 6 months), but after a year, all bets are off. If you want to take possible risks and experience the culinary monotony of a strictly low carbohydrate diet as outlined by Dr. Atkins, boredom itself may keep you from eating too many calories–one of many other theories as to how the Atkins diet (seems) to work. In my opinion an appealing low calorie diet, much like Weight Watchers, with ample foods from all groups, is a better choice than a life without bread or pasta. Add an occasional happy meal and life becomes sweeter, to borrow a phrase.
A nutritionist friend of mine recently returned from a year abroad. On coming home she was astounded to find everyone obsessed with low carbs and the certainty of successful weight loss with Atkins. Asked what she advises in terms of a good diet, she replied, "Everyone knows there's only four major food groups, Fat, Salt, and Sugar." "That's only three," I replied. "Sorry," she said, "I left out the most important one, Chocolate."
Martin F. Sturman, MD, FACP
Copyright 2004, Mathemedics, Inc.
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