Comparison of the Atkins, Zone, Ornish, and LEARN Diets -new study JAMA

[Guest guest]

New study published in JAMA allegedly comparing the efficacy of these

four diets (diet wars). Below that Dean Ornish responds...

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

D. Gardner, PhD; andre Kiazand, MD; Sofiya Alhassan,

PhD; Soowon Kim, PhD; Randall S. Stafford, MD, PhD; R. Balise,

PhD; Helena C. Kraemer, PhD; Abby C. King, PhD

JAMA. 2007;297:969-977.

Context Popular diets, particularly those low in carbohydrates, have

challenged current recommendations advising a low-fat,

high-carbohydrate diet for weight loss. Potential benefits and risks

have not been tested adequately.

Objective To compare 4 weight-loss diets representing a spectrum of

low to high carbohydrate intake for effects on weight loss and related

metabolic variables.

Design, Setting, and Participants Twelve-month randomized trial

conducted in the United States from February 2003 to October 2005

among 311 free-living, overweight/obese (body mass index, 27-40)

nondiabetic, premenopausal women.

Intervention Participants were randomly assigned to follow the Atkins

(n = 77), Zone (n = 79), LEARN (n = 79), or Ornish (n = 76) diets and

received weekly instruction for 2 months, then an additional 10-month

follow-up.

Main Outcome Measures Weight loss at 12 months was the primary

outcome. Secondary outcomes included lipid profile (low-density

lipoprotein, high-density lipoprotein, and non–high-density

lipoprotein cholesterol, and triglyceride levels), percentage of body

fat, waist-hip ratio, fasting insulin and glucose levels, and blood

pressure. Outcomes were assessed at months 0, 2, 6, and 12. The Tukey

studentized range test was used to adjust for multiple testing.

Results 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.

Conclusions In this study, premenopausal overweight and obese women

assigned to follow the Atkins diet, which had the lowest carbohydrate

intake, lost more weight and experienced more favorable overall

metabolic effects at 12 months than women assigned to follow the Zone,

Ornish, or LEARN diets. 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.

Dean Ornish responds:

Ornish: Why I Disagree With New Diet Study

A new comparison of four diets—including mine—is misleading and

riddled with problems.

WEB-EXCLUSIVE COMMENTARY

By Dean Ornish, M.D.

Special to Newsweek

Updated: 1:10 p.m. ET March 7, 2007

http://www.msnbc.msn.com/id/17490143/site/newsweek/