Cbelle -
I wish you luck on your weight loss. Please do follow the Atkins book closely. Stuff you hear "on the street" is quite different than what the actual diet actually recommends. I have never done it, but I had to do a little research for an article I wrote, which really surprised me.
The article below is one I wrote for a newsletter published by the Department of Geriatrics at the university where I work. At this point, the researcher's results are inconclusive, since it's still early in his study. But he does make some good points that you should be aware of (please note that the research is done on older people, but I expect it's still quite applicable to adults in general).
Article starts here:
The Atkins Diet: Physiologic and Metabolic Effects in the Elderly
The Atkins Diet, one of the most popular weight loss plans in recent decades, continues to generate significant scientific interest. High in both protein and fat, this widely publicized diet challenges our understanding of what constitutes healthy eating habits.
The Atkins Diet consists of four phases: Induction, Ongoing Weight Loss, Pre-Maintenance and Maintenance. The Induction phase seems to initiate rapid weight loss and is perhaps the most well-known, consisting of about 68 percent fat, 36 percent protein and 5 percent carbohydrates. The macronutrient proportions contrast sharply with current recommendations from the American Heart Association (AHA), which suggest that optimal weight loss is achieved on a diet with a maximum of 30 percent fat, 10 to 20 percent protein and 50 percent carbohydrates.
“There is some question of how the Atkins Diet works,” said Charles Lambert, Ph.D. “Some people think it changes a person’s metabolism, ‘revs it up,’ so to speak, so that the person burns more calories. Other people believe there is a satiety factor involved; that is, people on the Atkins diet eat so much fat that they don’t feel hungry and thus take in less calories.”
Lambert is seeking the answer to this and several other pieces of the Atkins puzzle. An assistant professor at the Donald W. Reynolds Department of Geriatrics at the University of Arkansas for Medical Sciences (UAMS), he conducts his work in the department’s Nutrition, Metabolism and Exercise Laboratory (NMEL) and the General Clinical Research Center (GCRC) at the adjacent John L. McClellan Memorial Veterans Hospital. Supported by a Beginning Grant-in-Aid from the AHA, Lambert is conducting a two-year study of how the diet affects healthy older subjects, aged 60 to 85 years, whose metabolism and physiology often differ from their younger counterparts.
“We’re keeping an open mind about this diet,” Lambert said. “On the surface, it doesn’t look very healthy. But, based on other studies of middle-aged individuals, at least in the short term it appears to be more effective in causing weight loss than a low fat, high carbohydrate diet that is usually recommended. And weight loss, no matter how it is attained, seems to drive several beneficial changes, such as an improvement in blood lipids.”
The Study
Lambert divides his subjects into three groups. The first follows the Atkins Diet verbatim, and the second follows a high carbohydrate, low fat, high fiber diet designed by William Evans, Ph.D., based on AHA recommendations. Evans is the director of the NMEL and a professor in the Department of Geriatrics. Members of the third group eat their normal, self-selected diet and serve as controls. All subjects receive one Centrum Silver vitamin and mineral supplement a day to compensate for any possible nutritional deficiencies that may be encountered.
Over a three-month period, The Atkins subjects first receive meals prepared by Amanda Wells, a registered dietitian at the GCRC, who strictly follows Atkins Diet guidelines. Lambert and Wells keep careful records of food eaten, number of calories consumed, and any weight loss. Then the subjects prepare their own food and attempt to maintain the same diet in a home setting. A primary target during this time is to examine the Atkins Diet’s effect on insulin sensitivity. Lambert utilizes a single-stage glucose clamp to study glucose disposal, as well as muscle biopsies to analyze the amount of fat in muscle, in order to examine the relationship between these two factors.
“Because the Atkins Diet is high in fat, we may see a high fat content in the muscles. Based on past research, that would impair the muscles’ ability to take up glucose,” Lambert said. “But since people obviously lose weight on this diet, they are in negative energy balance; thus, they may metabolize the excess fat in the muscle. In that case, would the dieters still have excess fat in the muscle? One expects that a body in negative energy balance would metabolize excess fat and therefore dispose of more glucose.”
In order to gain a clearer picture of how the Atkins Diet promotes weight loss, Lambert monitors and compares every subject’s metabolism, whether they follow the Atkins Diet or the high carbohydrate, low fat, high fiber meal plan. The metabolic rates are taken at rest and during a half hour of moderate intensity exercise. The subjects’ metabolic rates are also monitored for four hours after eating to examine how they metabolize a meal.
A final goal of the study is to determine the effects a high protein, low carbohydrate diet has on cognitive function. “A low carbohydrate diet depletes the blood of glucose, which is the brain’s primary energy source,” Lambert explained. “In the absence of glucose, the brain can function on ketones, which are metabolites of fat. But there may be a lag time during the conversion period, before the brain is fully prepared to use ketones, when a person’s cognitive function may be impaired.”
Lambert will administer a battery of tests to each subject on all three diet plans, before and during the diets, to determine any differences in cognitive processes. The test battery was developed by Eva Hogervorst, Ph.D., a former department faculty member who is currently a research scientist and epidemiologist at the University of Oxford in England. Lambert will send the results to Hogervorst, a cognitive specialist, for analysis.
Conclusion
Although it is still too early in the study to determine any effects the Atkins Diet may have on insulin sensitivity, metabolism and cognitive function, Lambert has made several other observations about the diet. He noted that weight loss rates from both diets have been comparable, with the average being about 10 pounds in three months. However, individuals on each diet have lost greater amounts: one subject on the high carbohydrate, low fat, high fiber diet lost 23 pounds in 12 weeks, and one on the Atkins Diet lost 20 pounds in the same time frame.
“In addition, we have witnessed an improvement in blood lipids in some elderly subjects on the Atkins Diet, whose total cholesterol and LDL cholesterol dropped quite drastically. So far, none of our Atkins Diet participants have experienced any renal function problems, which is a possible effect of a high protein diet, especially for the elderly.”
Despite the positive results to date, Lambert emphasizes that he has only examined the short-term effects of the diet and is aware of several harmful effects the diet may pose, including an increased risk of gastrointestinal tract cancer, since low fiber diets cause food to remain longer in the gastrointestinal tract. Previous studies have also shown that the Atkins Diet can cause negative calcium balance in the short term, which could result in bone loss over time.
“I think there are some real questions about this diet in the long term,” Lambert said. “An extended study is needed to thoroughly examine them. Such a study would take several years, even decades, because the Atkins Diet is supposed to promote a lifestyle change.”
