A new clinical trial published in the Journal of the American Medical Association showed that women following the Atkins diet lost more weight over a one-year period than women following other dietary plans. Expect supporters of the Atkins-style low-carbohydrate diets to cite this research as proof that their diet is superior to older low-fat weight loss diets that remain the standard of care in most medical settings.

In this new study, participants followed one of four diets for the entire year. The diets were as follows:

  • Atkins Diet: a low-carbohydrate, high-protein strategy
  • Ornish Diet: a very-low-fat, vegetarian diet
  • Zone Diet: a diet that attempts to balance protein, carbohydrates, and fats at every meal
  • LEARN Diet: a diet that follows a more traditional low-fat, high-fiber strategy

In addition to losing more weight than the people assigned to the other diet strategies (about 10 pounds, compared with about 5 in other groups), the Atkins diet participants had favorable changes in their cholesterol levels and no changes in blood sugar control or blood pressure. Critics have long been concerned about the possibility of the Atkins Diet leading to dangerous changes in each of these three important areas.

Color me unconvinced. I don’t believe that this study teaches us anything about the relative efficacy of any diets. This is because the average participant in this study didn’t even come close to following the recommended dietary strategy. The people assigned to the Ornish Diet, for instance, on average ate three times as much fat as this diet allows. Similarly, people following the Zone diet were supposed to get 30% of their calories from protein, but only managed to get 20% by the end of the study. It would have been very useful to see a little more information about what the food sources of the calories were (e.g., did the carbohydrates come from sweets or fruits and vegetables) to know more about why people failed to meet prescribed diet interventions.

The Atkins Diet participants were the closest to actually following the recommended diet, perhaps explaining the better outcome in this group. A similarly designed trial published in JAMA two years ago showed no real difference among any of these diets in weight loss efficacy.

My concern with the Atkins dietary strategy is that people following this diet over a period of years may develop health problems related to the high total fat and saturated fat content of the diet. Previously published research indicates that diets high in saturated fat can lead to insulin resistance (an important step toward diabetes), high blood pressure, and high cholesterol. While in the short term, the weight loss from the Atkins Diet may mask this effect, over a period of years, this effect would seem likely.

A much more important and obvious point than relative diet efficacy, at least to me, is the evidence that people do not easily adopt new diet strategies. Even though each person in this diet was given eight weeks of intensive dietary counseling, the diets people reported at the end of a year looked very little like the diets they were supposed to be eating.

It is my belief that the best way to build a weight loss diet is to start with understanding of the person’s current diet. Then, work together with that person to identify and intervene with the most problematic aspects of that diet and finds ways to move to a more whole foods diet. This approach is far more effective than starting with a one-size-fits-all strategy, meets the individual’s specific needs, and sets a diet up for success rather than failure.

References:

  1. Gardner CD, Kiazand A, Alhassan S, et al. Comparison of the Atkins, Zone, Ornish, and LEARN diets for change in weight and related risk factors among overweight premenopausal women: the A TO Z Weight Loss Study: a randomized trial. JAMA. 2007;297(9):969-77.
  2. Dansinger ML, Gleason JA, Griffith JL, et al. Comparison of the Atkins, Ornish, Weight Watchers, and Zone diets for weight loss and heart disease risk reduction: a randomized trial. JAMA. 2005;293(1):43-53.
  3. Rasmussen O, Lauszus FF, Christiansen C, et al. Differential effects of saturated and monounsaturated fat on blood glucose and insulin responses in subjects with non-insulin-dependent diabetes mellitus. Am J Clin Nutr. 1996;63(2):249-53.
  4. Thomsen C, Rasmussen O, Lousen T, et al. Differential effects of saturated and monounsaturated fatty acids on postprandial lipemia and incretin responses in healthy subjects. Am J Clin Nutr. 1999;69(6):1135-43
  5. Rasmussen BM, Vessby B, Uusitupa M, et al. Effects of dietary saturated, monounsaturated, and n-3 fatty acids on blood pressure in healthy subjects. Am J Clin Nutr. 2006;83(2):221-6

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