Thursday, October 29, 2009

The Atkins Diet May Not Be So Unhealthy After All — A Comparison Trial with Three Other Diets

In a head-to-head comparison trial of four weight-loss diets, the Atkins diet came out on top. The findings, though modest and preliminary, appear to challenge the prevailing medical wisdom
about the best diet as one that is low in fat and high in carbohydrate. The study was led by Christopher D. Gardner, PhD, Stanford University Medical School, and published in the March 7, 2007 issue of the Journal of the American Medical Association.

The 249 participants in this trial were overweight or obese women under the age of 50 without diabetes. All had been randomly assigned to follow one of these four diets for one year: The Atkins (high protein, very low in carbohydrate), Zone (low in carbohydrate with emphasis on fruits and vegetables), Ornish (high in complex carbohydrate, extremely low in fat) and LEARN (low in fat, high in carbohydrate).

The first three are diets popularized via the media and books, two of them by physicians—Dr. Robert Atkins and Dr. Dean Ornish. LEARN is a diet/lifestyle program central to the national guidelines. It involves a “prudent diet that included 55% to 60% energy from carbohydrate and less than 10% energy from saturated fat.”

Weight Loss Modest for All

After one year the amount of weight lost was: 10.4 lbs. for Atkins, 3.5 lbs. for Zone, 5.7 lbs. for
LEARN, and 4.8 lbs. for Ornish. Initially, the women on the Atkins diet lost weight faster but in
time the things began to even out across the four groups. Something that showed up in previous
studies of the Atkins diet.

The women received weekly instructions about the assigned diet for two months and at 10 months. In keeping with the fact that most Americans follow diets from a book, each woman received a copy of one of the four following books, according to her
assigned diet: Dr. Atkins’ New Diet Revolution, Enter the Zone, The LEARN Manual for Weight Management or Eat More, Weigh Less by Dean Ornish.

Heart Risk Factors Checked

Before and after the trial, the women’s cholesterol and levels of insulin, glucose and blood pressure were measured. Results for the women who had been on the Atkins diet were either comparable with or better than those of the women on the other diets.

Dr. Gardner and colleagues noted, “Many concerns have been expressed that low-carbohydrate weight-loss diets, high in total and saturated fat, will adversely
affect blood lipid levels and cardiovascular risk. These concerns have not been substantiated.” In fact, the authors cite five trials published in the last four years that produced findings similar to their own—in terms of triglycerides, high-density lipoproteins (“good cholesterol”) and blood pressure—that favor very-low-carbohydrate diets.

The researchers, however, state that they are not able to determine whether these favorable metabolic effects are attributable to the low-carbohydrate intake or other aspects of the Atkins diet, such as the high protein intake.

Dr. Gardner and colleagues concluded, “While questions remain about long-term effects and mechanisms, a low-carbohydrate, high-protein, high-fat diet may be considered a feasible alternative recommendation for weight loss.” This study was funded by grants from the U.S. National Institutes of Health.

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