Clinical Comparison of Atkins, Zone, Ornish & LEARN Weight Loss Diets

Readers frequently ask about the effects of a fad- and low carbohydrate diets.

There is consistent clinical evidence that modulating carbohydrate intake affects body composition and other factors in humans.

Here is the outcome of one clinical study from Stanford University comparing several of these diets over a year:

“…premenopausal overweight and obese women assigned to follow the Atkins diet, which had the lowest carbohydrate intake, lost more weight at 12 months than women assigned to follow the Zone diet, and had experienced comparable or more favorable metabolic effects than those assigned to the Zone, Ornish, or LEARN diets (P<.05). 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.”

Of note, the researchers do not explicitly promote (or deny) the brand names, but the macronutrient content. In otherwords, it’s conceivable that similar results could be achieved with similar (but not identical diets).

When reading these trials, its important to read the selection criteria for the participants and the study design.

In  this case, postmenopausal and overweight or obese women (determined by BMI) is a population  often  targeted by marketers of  weight loss products.

Other interesting points:

  • Weight loss was greater for women in the Atkins diet group compared with the other diet groups at 12 months, and mean 12-month weight loss was significantly different between the Atkins and Zone diets (P<.05).
  • Mean 12-month weight loss was as follows: Atkins, -4.7 kg (95% confidence interval [CI], -6.3 to -3.1 kg), Zone, -1.6 kg (95% CI, -2.8 to -0.4 kg), LEARN, -2.6 kg (-3.8 to -1.3 kg), and Ornish, -2.2 kg (-3.6 to -0.8 kg). Weight loss was not statistically different among the Zone, LEARN, and Ornish groups.
  • At 12 months, secondary outcomes for the Atkins group were comparable with or more favorable than the other diet groups.

Here is the link to the Clinical Trial, if you’d like to read further. Thanks for reading.


One thought on “Clinical Comparison of Atkins, Zone, Ornish & LEARN Weight Loss Diets

  1. Were these women told not to change their current level of activity and supplementation for the duration of the year? I’m curious how the “Paleo” diet or a vegan diet fit into effective weight loss. It would be interesting to collect data on these women’s gut micro-biome at the start and end of the year to see what the difference is in bacteria diversity. Future of probiotics… personalization for optimal physical and mental health?


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