Long-term effects of 4 popular diets on weight loss and cardiovascular risk factors: a systematic review of randomized controlled trials.
BACKGROUND
We conducted a systematic review to examine the efficacy of the Atkins, South Beach, Weight Watchers (WW), and Zone diets, with a particular focus on sustained weight loss at ≥12 months.


RESULTS
We systematically searched MEDLINE, EMBASE, and the Cochrane Library of Clinical Trials to identify randomized controlled trials (RCTs) published in English with follow-up ≥4 weeks that examined the effects of these 4 popular diets on weight loss and cardiovascular risk factors. We identified 12 RCTs (n=2559) with follow-up ≥12 months: 10 versus usual care (5 Atkins, 4 WW, and 1 South Beach) and 2 head-to-head (1 of Atkins, WW, and Zone, and 1 of Atkins, Zone, and control). At 12 months, the 10 RCTs comparing popular diets to usual care revealed that only WW was consistently more efficacious at reducing weight (range of mean changes: -3.5 to -6.0 kg versus -0.8 to -5.4 kg; P<0.05 for 3/4 RCTs). However, the 2 head-to-head RCTs suggest that Atkins (range: -2.1 to -4.7 kg), WW (-3.0 kg), Zone (-1.6 to -3.2 kg), and control (-2.2 kg) all achieved modest long-term weight loss. Twenty-four-month data suggest that weight lost with Atkins or WW is partially regained over time.


CONCLUSIONS
Head-to-head RCTs, providing the most robust evidence available, demonstrated that Atkins, WW, and Zone achieved modest and similar long-term weight loss. Despite millions of dollars spent on popular commercial diets, data are conflicting and insufficient to identify one popular diet as being more beneficial than the others.
From the Centre for Clinical Epidemiology (R.A., K.B.F., S.M.W., M.J.E.), Lady Davis Institute (R.A., K.B.F., S.M.W., E.L.S., M.J.E.), Department of Medicine (K.B.F., E.L.S.), and Division of Cardiology (M.J.E.), Jewish General Hospital, McGill University, Montreal, QC, Canada; Division of Clinical Epidemiology (K.B.F.), Department of Epidemiology, Biostatistics, and Occupational Health (K.B.F., L.J., M.J.E.), and Department of Ophthalmology (S.M.W.), McGill University, Montreal, QC, Canada; Division of Cardiology, McGill University Health Centre/Royal Victoria Hospital, Montreal, QC, Canada (J.G.); Division of Clinical Epidemiology, McGill University Health Centre, Montreal, QC, Canada (L.J.); Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Québec, QC, Canada (P.P., S.R.); and Faculté de pharmacie, Université Laval, Québec, QC, Canada (P.P.).
Renée
R
Atallah
From the Centre for Clinical Epidemiology (R.A., K.B.F., S.M.W., M.J.E.), Lady Davis Institute (R.A., K.B.F., S.M.W., E.L.S., M.J.E.), Department of Medicine (K.B.F., E.L.S.), and Division of Cardiology (M.J.E.), Jewish General Hospital, McGill University, Montreal, QC, Canada; Division of Clinical Epidemiology (K.B.F.), Department of Epidemiology, Biostatistics, and Occupational Health (K.B.F., L.J., M.J.E.), and Department of Ophthalmology (S.M.W.), McGill University, Montreal, QC, Canada; Division of Cardiology, McGill University Health Centre/Royal Victoria Hospital, Montreal, QC, Canada (J.G.); Division of Clinical Epidemiology, McGill University Health Centre, Montreal, QC, Canada (L.J.); Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Québec, QC, Canada (P.P., S.R.); and Faculté de pharmacie, Université Laval, Québec, QC, Canada (P.P.).
Kristian B
KB
Filion
From the Centre for Clinical Epidemiology (R.A., K.B.F., S.M.W., M.J.E.), Lady Davis Institute (R.A., K.B.F., S.M.W., E.L.S., M.J.E.), Department of Medicine (K.B.F., E.L.S.), and Division of Cardiology (M.J.E.), Jewish General Hospital, McGill University, Montreal, QC, Canada; Division of Clinical Epidemiology (K.B.F.), Department of Epidemiology, Biostatistics, and Occupational Health (K.B.F., L.J., M.J.E.), and Department of Ophthalmology (S.M.W.), McGill University, Montreal, QC, Canada; Division of Cardiology, McGill University Health Centre/Royal Victoria Hospital, Montreal, QC, Canada (J.G.); Division of Clinical Epidemiology, McGill University Health Centre, Montreal, QC, Canada (L.J.); Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Québec, QC, Canada (P.P., S.R.); and Faculté de pharmacie, Université Laval, Québec, QC, Canada (P.P.).
Susan M
SM
Wakil
From the Centre for Clinical Epidemiology (R.A., K.B.F., S.M.W., M.J.E.), Lady Davis Institute (R.A., K.B.F., S.M.W., E.L.S., M.J.E.), Department of Medicine (K.B.F., E.L.S.), and Division of Cardiology (M.J.E.), Jewish General Hospital, McGill University, Montreal, QC, Canada; Division of Clinical Epidemiology (K.B.F.), Department of Epidemiology, Biostatistics, and Occupational Health (K.B.F., L.J., M.J.E.), and Department of Ophthalmology (S.M.W.), McGill University, Montreal, QC, Canada; Division of Cardiology, McGill University Health Centre/Royal Victoria Hospital, Montreal, QC, Canada (J.G.); Division of Clinical Epidemiology, McGill University Health Centre, Montreal, QC, Canada (L.J.); Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Québec, QC, Canada (P.P., S.R.); and Faculté de pharmacie, Université Laval, Québec, QC, Canada (P.P.).
Jacques
J
Genest
From the Centre for Clinical Epidemiology (R.A., K.B.F., S.M.W., M.J.E.), Lady Davis Institute (R.A., K.B.F., S.M.W., E.L.S., M.J.E.), Department of Medicine (K.B.F., E.L.S.), and Division of Cardiology (M.J.E.), Jewish General Hospital, McGill University, Montreal, QC, Canada; Division of Clinical Epidemiology (K.B.F.), Department of Epidemiology, Biostatistics, and Occupational Health (K.B.F., L.J., M.J.E.), and Department of Ophthalmology (S.M.W.), McGill University, Montreal, QC, Canada; Division of Cardiology, McGill University Health Centre/Royal Victoria Hospital, Montreal, QC, Canada (J.G.); Division of Clinical Epidemiology, McGill University Health Centre, Montreal, QC, Canada (L.J.); Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Québec, QC, Canada (P.P., S.R.); and Faculté de pharmacie, Université Laval, Québec, QC, Canada (P.P.).
Lawrence
L
Joseph
From the Centre for Clinical Epidemiology (R.A., K.B.F., S.M.W., M.J.E.), Lady Davis Institute (R.A., K.B.F., S.M.W., E.L.S., M.J.E.), Department of Medicine (K.B.F., E.L.S.), and Division of Cardiology (M.J.E.), Jewish General Hospital, McGill University, Montreal, QC, Canada; Division of Clinical Epidemiology (K.B.F.), Department of Epidemiology, Biostatistics, and Occupational Health (K.B.F., L.J., M.J.E.), and Department of Ophthalmology (S.M.W.), McGill University, Montreal, QC, Canada; Division of Cardiology, McGill University Health Centre/Royal Victoria Hospital, Montreal, QC, Canada (J.G.); Division of Clinical Epidemiology, McGill University Health Centre, Montreal, QC, Canada (L.J.); Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Québec, QC, Canada (P.P., S.R.); and Faculté de pharmacie, Université Laval, Québec, QC, Canada (P.P.).
Paul
P
Poirier
From the Centre for Clinical Epidemiology (R.A., K.B.F., S.M.W., M.J.E.), Lady Davis Institute (R.A., K.B.F., S.M.W., E.L.S., M.J.E.), Department of Medicine (K.B.F., E.L.S.), and Division of Cardiology (M.J.E.), Jewish General Hospital, McGill University, Montreal, QC, Canada; Division of Clinical Epidemiology (K.B.F.), Department of Epidemiology, Biostatistics, and Occupational Health (K.B.F., L.J., M.J.E.), and Department of Ophthalmology (S.M.W.), McGill University, Montreal, QC, Canada; Division of Cardiology, McGill University Health Centre/Royal Victoria Hospital, Montreal, QC, Canada (J.G.); Division of Clinical Epidemiology, McGill University Health Centre, Montreal, QC, Canada (L.J.); Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Québec, QC, Canada (P.P., S.R.); and Faculté de pharmacie, Université Laval, Québec, QC, Canada (P.P.).
Stéphane
S
Rinfret
From the Centre for Clinical Epidemiology (R.A., K.B.F., S.M.W., M.J.E.), Lady Davis Institute (R.A., K.B.F., S.M.W., E.L.S., M.J.E.), Department of Medicine (K.B.F., E.L.S.), and Division of Cardiology (M.J.E.), Jewish General Hospital, McGill University, Montreal, QC, Canada; Division of Clinical Epidemiology (K.B.F.), Department of Epidemiology, Biostatistics, and Occupational Health (K.B.F., L.J., M.J.E.), and Department of Ophthalmology (S.M.W.), McGill University, Montreal, QC, Canada; Division of Cardiology, McGill University Health Centre/Royal Victoria Hospital, Montreal, QC, Canada (J.G.); Division of Clinical Epidemiology, McGill University Health Centre, Montreal, QC, Canada (L.J.); Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Québec, QC, Canada (P.P., S.R.); and Faculté de pharmacie, Université Laval, Québec, QC, Canada (P.P.).
Ernesto L
EL
Schiffrin
From the Centre for Clinical Epidemiology (R.A., K.B.F., S.M.W., M.J.E.), Lady Davis Institute (R.A., K.B.F., S.M.W., E.L.S., M.J.E.), Department of Medicine (K.B.F., E.L.S.), and Division of Cardiology (M.J.E.), Jewish General Hospital, McGill University, Montreal, QC, Canada; Division of Clinical Epidemiology (K.B.F.), Department of Epidemiology, Biostatistics, and Occupational Health (K.B.F., L.J., M.J.E.), and Department of Ophthalmology (S.M.W.), McGill University, Montreal, QC, Canada; Division of Cardiology, McGill University Health Centre/Royal Victoria Hospital, Montreal, QC, Canada (J.G.); Division of Clinical Epidemiology, McGill University Health Centre, Montreal, QC, Canada (L.J.); Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec, Québec, QC, Canada (P.P., S.R.); and Faculté de pharmacie, Université Laval, Québec, QC, Canada (P.P.). mark.eisenberg@mcgill.ca.
Mark J
MJ
Eisenberg
D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control; D004032:Diet / Q000379:methods*; D014943:Global Health; D006801:Humans; D009017:Morbidity / Q000639:trends; D009765:Obesity / Q000150:complications / Q000178:diet therapy / Q000453:epidemiology; D016032:Randomized Controlled Trials as Topic; D012307:Risk Factors; D015431:Weight Loss
diet, carbohydrate-restricted; weight loss