Comparison of the Atkins, Zone, Ornish, and LEARN Diets for Change in Weight and Related Risk Factors Among Overweight Premenopausal Women

Abstract

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 (PϽ.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. Trial Registration clinicaltrials.gov Identifier: NCT00079573

Role of Carbohydrate Modification in Weight Management among Obese Children: A Randomized Clinical Trial

“…These findings are consistent with other diet comparisons in obese adolescents 16 and adults. 9, 12, 13, 32, 33 However; the results of our study do not support the hypothesis that CHO-modified diets would be more effective in improving weight status than a standard portion-controlled diet among obese children. Subjects in all 3 diet groups showed significant improvements in adiposity measures (BMI z-score, %BF and WC) during the initial 3-month intervention with relatively intensive intervention and contact with study dietitians.…”

Differential Effect of Fat Intake on Blood Pressure in Healthy Japanese Women with and without the Variant of Fat Mass and Obesity-Associated Gene

“…Recently, Yang et al 24) reported the results of a metaanalysis of the effects of a low-fat, high-carbohydrate diet vs. a low-carbohydrate, high-fat diet on blood pressure, and systolic and diastolic blood pressures were not significantly different between the two diets in eleven randomized clinical trials conducted mainly in the United States and Europe. The effect of fat intake on systolic blood pressure observed in our study, conducted for Japanese women, was consistent with the results reported by Lu A genome-wide association study found that the FTO gene is associated with BMI and obesity 9,13,25) . Carriers of the obesity-risk A-allele have a higher risk of obesity compared to carriers of the T-allele, mainly because of elevations in appetite and energy intake 26,27) .…”

Effects of Low-Carbohydrate and Low-Fat Diets

“…Our results with regard to body weight are consistent with those of other trials (23, 24) and a recent meta-analysis (25). The underlying mechanisms that may account for differences in weight loss by diet are still not fully identified, but a recent study indicated that low-carbohydrate diets may have a more favorable effect on resting energy expenditure and total energy expenditure than low-fat diets (26).…”