A calorie is a calorie, right? Well, not so fast!

A calorie is a calorie, right? Well, not so fast!

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A low-carbohydrate, high-protein diet may increase cardiovascular disease risk

The hotly debated topic about the importance of diet type was in the news recently. In terms of weight loss, a calorie may be a calorie. However, in terms of its effect on body composition, disease modification and prevention, this may not be true. Some diets may have more beneficial or detrimental effects on health than others.

A low-carb, high-protein and high-fat diet

There was a recent study that showed a low-carbohydrate, high-protein diet was more effective at burning calories after initial weight loss than other diets (JAMA 2012 Jun 27; 307:2627). In this study, patients were given a 12-week “washout period” where they lost 10 to 15 percent of their body weight. They were then put on three different diets and assessed over a four-week period with each: a low glycemic index diet, a low-fat diet and a very low-carbohydrate diet.

The diet that seemed to show the most benefit for maintaining weight loss was the very low-carbohydrate diet, which was high in protein and high in fat — an Atkins-type diet. This diet lowered the resting energy expenditure the least, meaning that the body burned calories more efficiently. Patients expended 300 more calories on this low-carbohydrate diet than on the low-fat diet and 150 more calories than on the low glycemic index diet. This study was a prospective (forward-looking) randomized crossover trial involving 21 young obese and overweight adults; each participant was on each diet for a month. However, the study’s duration may be too short to tell us anything meaningful.

Why did the low-carbohydrate diet show the best results for maintaining weight loss and burning more calories? This question was answered in the Science Times section of The New York Times on July 9 by Dr. Jules Hirsch, emeritus physician in chief at Rockefeller University. He has a background that includes 60 years of obesity research, and he believes that the difference seen with the Atkins-type diet was due to water loss. He says that, ultimately, weight loss is dependent on the traditional formula — the amount of calories consumed minus the amount of calories burned on a daily basis — not the diet’s composition. He aptly points out, however, that diets’ compositions are important, because they affect patients’ overall health.

Low-carb, high-protein diet negative effects

Ironically, another study published the same week as the JAMA study showed a potentially increased risk of cardiovascular disease with a low-carbohydrate, high-protein diet (BMJ 2012 Jun 26; 344:e4026). The study was a prospective trial involving 43,396 Swedish women with a 15.7 year duration. There was a 4 percent increase in risk for every 10 percent increase in protein or, as the authors point out, for every additional boiled egg consumed. This is a modest, yet harmful, effect.

Low-carb, high-protein diets have also shown an increased risk of kidney stones. There was a doubling of uric acid levels in the kidney and a significant increase in urine calcium levels over a six-week period (Am J Kidney Dis. 2002 Aug;40(2):265-74). The weaknesses of this study are that it was small, 10 participants, and short in duration. However, it does make you think that low-carb, high-protein diets from animal sources may not be the best option for overall health.

Interestingly, another study showed that a low-carb, high-protein diet may vary in its effects, depending on the source of protein (Ann Intern Med 2010;153:289-298). If high protein levels and fat came from animal sources, then there was an increased risk of death from heart disease and cancer — 14 percent and 28 percent respectively. However, if the protein and fat came from plant sources, such as nuts and beans, the risks of all-cause mortality and mortality from cardiovascular disease were decreased by 20 percent and 23 percent, respectively, over the same length of time. The study was a meta-analysis (a group of two studies) that included the Nurses’ Health Study, with over 85,000 women, and the Physicians’ Health Study, with approximately 45,000 men, with a duration of 26 years and 20 years of follow up, respectively.

Mediterranean diet’s effect on body composition

We know a Mediterranean-type diet has profound effects on risk reduction for many diseases (BMJ 2008;337:a1344). Recently, I had a patient who began a nutrient-rich, plant-based diet with an incremental approach. After one month of having altered one meal a day, the patient lost two pounds.
However, this was not the whole story. Using a clinical-trial-grade body composition scale, I found that the patient had lost 10 pounds of fat mass, 4 percent body fat and had gained 7 pounds of fat-free mass, most of it water, without having exercised during the month. This demonstrates that a diet can do far more than alter body weight.

No one will argue that weight loss is important, especially for those patients who are obese. However, when looking at a diet, it is important to also consider its effectiveness for disease treatment and prevention. Diets that are considered to be most effective include a Mediterranean-type diet, the DASH diet, the Ornish diet and any other diet that is plant-based and nutrient-rich. Why lose weight for vanity only, when you can lose weight and gain health at the same time?

Dr. Dunaief is a speaker, author and local lifestyle medicine physician focusing on the integration of medicine, nutrition, fitness and stress management. For further information, go to the website www.medicalcompassmd.com and/or consult your personal physician.