No significant differences were observed for weight , waist circumference , fat mass , blood lipids ( i.e. total cholesterol , LDL-cholesterol , HDL-cholesterol , triacylglycerols ) , C-reactive protein , diastolic and systolic blood pressure , fasting glucose and glycosylated hemoglobin .
Sensitivity analysis of high quality RCTs confirmed the data of the primary analyses , while exclusion of studies with diabetic subjects result ed in an additional benefit of high-protein diets with respect to a more marked increase in HDL-cholesterol .
Conclusion According to the present meta- analysis of long-term RCTs , high-protein diets exerted neither specific beneficial nor detrimental effects on outcome markers of obesity , cardiovascular disease or glycemic control .
Background Meta-analyses of short-term studies indicate favorable effects of higher protein vs. lower protein diets on health outcomes like adiposity or cardiovascular risk factors , but their long-term effects are unknown .
Comparison of the Atkins, Ornish, Weight Watchers, and Zone diets for weight loss and heart disease risk reduction: a randomized trial.
CONTEXT The scarcity of data addressing the health effects of popular diets is an important public health concern , especially since patients and physicians are interested in using popular diets as individualized eating strategies for disease prevention . OBJECTIVE To assess adherence rates and the effectiveness of 4 popular diets ( Atkins , Zone , Weight Watchers , and Ornish ) for weight loss and cardiac risk factor reduction . DESIGN , SETTING , AND PARTICIPANTS A single-center r and omized trial at an academic medical center in Boston , Mass , of overweight or obese ( body mass index : mean , 35 ; range , 27 - 42 ) adults aged 22 to 72 years with known hypertension , dyslipidemia , or fasting hyperglycemia . Participants were enrolled starting July 18 , 2000 , and r and omized to 4 popular diet groups until January 24 , 2002 . INTERVENTION A total of 160 participants were r and omly assigned to either Atkins ( carbohydrate restriction , n=40 ) , Zone ( macronutrient balance , n=40 ) , Weight Watchers ( calorie restriction , n=40 ) , or Ornish ( fat restriction , n=40 ) diet groups . After 2 months of maximum effort , participants selected their own levels of dietary adherence . MAIN OUTCOME MEASURES One-year changes in baseline weight and cardiac risk factors , and self-selected dietary adherence rates per self-report . RESULTS Assuming no change from baseline for participants who discontinued the study , mean ( SD ) weight loss at 1 year was 2.1 ( 4.8 ) kg for Atkins ( 21 [ 53 % ] of 40 participants completed , P = .009 ) , 3.2 ( 6.0 ) kg for Zone ( 26 [ 65 % ] of 40 completed , P = .002 ) , 3.0 ( 4.9 ) kg for Weight Watchers ( 26 [ 65 % ] of 40 completed , P < .001 ) , and 3.3 ( 7.3 ) kg for Ornish ( 20 [ 50 % ] of 40 completed , P = .007 ) . Greater effects were observed in study completers . Each diet significantly reduced the low-density lipoprotein/high-density lipoprotein ( HDL ) cholesterol ratio by approximately 10 % ( all P<.05 ) , with no significant effects on blood pressure or glucose at 1 year . Amount of weight loss was associated with self-reported dietary adherence level ( r = 0.60 ; P<.001 ) but not with diet type ( r = 0.07 ; P = .40 ) . For each diet , decreasing levels of total/HDL cholesterol , C-reactive protein , and insulin were significantly associated with weight loss ( mean r = 0.36 , 0.37 , and 0.39 , respectively ) with no significant difference between diets ( P = .48 , P = .57 , P = .31 , respectively ) . CONCLUSIONS Each popular diet modestly reduced body weight and several cardiac risk factors at 1 year . Overall dietary adherence rates were low , although increased adherence was associated with greater weight loss and cardiac risk factor reductions for each diet group
No significant differences were observed for weight , waist circumference , fat mass , blood lipids ( i.e. total cholesterol , LDL-cholesterol , HDL-cholesterol , triacylglycerols ) , C-reactive protein , diastolic and systolic blood pressure , fasting glucose and glycosylated hemoglobin .
Sensitivity analysis of high quality RCTs confirmed the data of the primary analyses , while exclusion of studies with diabetic subjects result ed in an additional benefit of high-protein diets with respect to a more marked increase in HDL-cholesterol .
Conclusion According to the present meta- analysis of long-term RCTs , high-protein diets exerted neither specific beneficial nor detrimental effects on outcome markers of obesity , cardiovascular disease or glycemic control .
Background Meta-analyses of short-term studies indicate favorable effects of higher protein vs. lower protein diets on health outcomes like adiposity or cardiovascular risk factors , but their long-term effects are unknown .