Atkins equally or more effective for weight loss in premenopausal women

Clinical Question

Which diet is most effective for maintaining weight loss in premenopausal women at 1 year?

Bottom Line

In this study, premenopausal overweight and obese women on the Atkins diet lost comparable or more weight than similar women following other diet plans, including the Zone, Ornish, or LEARN (Lifestyle, Exercise, Attitudes, Relationships, and Nutrition) diets. In addition, women on the Atkins diet showed equally or more improved overall metabolic effects. The difference in weight loss between the Atkins and Zone diet was statistically significant, but weight loss was not different among the other diets. (LOE = 1b)


Gardner CD, Kiazand A, Alhassan S, et al. Comparison of the Atkins, Zone, Ornish, and LEARN diets for change in weight and weight related risk factors among overweight premenopausal women. The A to Z weight loss study: A randomized controlled trial. JAMA 2007;297:969-977.  [PMID:17341711]

Study Design

Randomized controlled trial (single-blinded)






Outpatient (any)


These investigators randomly assigned (concealed allocation assignment) 311 premenopausal women, aged 25 to 50 years, with a body mass index (BMI) of 27 to 40 to follow 1 of 4 diets: Atkins (very low carbohydrate, high fat), Zone (low carbohydrate, moderate fat), LEARN (low fat, high carbohydrate), or Ornish (very high carbohydrate, low fat). Exclusion criteria included an uncontrolled medical condition, weight fluctuations in the previous 2 months, pregnancy or attempting to conceive, and low BMI. Participants were encouraged to read the book written for their specific group's diet, as well as attend a 1-hour class led by a dietician for 8 weeks. Patients provided feedback at 2, 6, and 12 months by telephone to individuals blinded to treatment group assignment. The primary outcome was weight loss at 12 months, with secondary outcomes including fasting lipid profile, percentage body fat, waist-hip ratio, fasting insulin levels, glucose levels, and blood pressure. Follow-up occurred for all subjects at 12 months. Using intention to treat analysis, participants assigned to the Atkins group lost more mean weight (-4.7 kg; 95% CI, -6.3 to -3.1 kg) than the Zone (-1.6 kg; -0.8 to -0.4 kg), LEARN (-2.2 kg; -3.6 to -0.8 kg) , and Ornish (-2.6 kg; -3.8 to -1.3 kg) groups. The difference between the Atkins and Zone diets was statistically significant, but no other differences between any of the diets were significant. The Atkins group also saw significant reductions at 1 year in low-density lipoprotein, but not high-density lipoprotein cholesterol and systolic blood pressure. No significant differences in insulin levels or fasting glucose levels were seen in any group. Weight loss was greatest at 6 months for all diets with many patients regaining some weight at 1 year.
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