An 18-mo randomized trial of a low-glycemic-index diet and weight change in Brazilian women.
BACKGROUND
Despite interest in the glycemic index diets as an approach to weight control, few long-term evaluations are available.


OBJECTIVE
The objective was to investigate the long-term effect of a low-glycemic-index (LGI) diet compared with that of a high-glycemic-index (HGI) diet; all other dietary components were equal.


METHODS
After a 6-wk run-in, we randomly assigned 203 healthy women [body mass index (in kg/m2): 23-30] aged 25-45 y to an LGI or an HGI diet with a small energy restriction. The primary outcome measure was weight change at 18 mo. Secondary outcomes included hunger and fasting insulin and lipids.


RESULTS
Despite requiring a run-in and the use of multiple incentives, only 60% of the subjects completed the study. The difference in glycemic index between the diets was approximately 35-40 units (40 compared with 79) during all 18 mo of follow-up, and the carbohydrate intake from energy remained at approximately 60% in both groups. The LGI group had a slightly greater weight loss in the first 2 mo of follow-up (-0.72 compared with -0.31 kg), but after 12 mo of follow-up both groups began to regain weight. After 18 mo, the weight change was not significantly different (P = 0.93) between groups (LGI: -0.41 kg; HGI: -0.26 kg). A greater reduction was observed in the LGI diet group for triacylglycerol (difference = -16.4 mg/dL; P = 0.11) and VLDL cholesterol (difference = -3.7 mg/dL; P = 0.03).


CONCLUSIONS
Long-term weight changes were not significantly different between the HGI and LGI diet groups; therefore, this study does not support a benefit of an LGI diet for weight control. Favorable changes in lipids confirmed previous results.
Sichieri
Rosely
R
Department of Epidemiology, Institute of Social Medicine, State University of Rio de Janeiro, Rio de Janeiro, Brazil. sichieri@ims.uerj.br
Moura
Anibal S
AS
Genelhu
Virginia
V
Hu
Frank
F
Willett
Walter C
WC
D000328:Adult; D001938:Brazil; D050528:Diet, Carbohydrate-Restricted; D004038:Diet, Reducing; D004040:Dietary Carbohydrates / Q000008:administration & dosage* / Q000145:classification; D004041:Dietary Fats / Q000008:administration & dosage; D005260:Female; D005500:Follow-Up Studies; D038321:Glycemic Index; D006801:Humans; D006815:Hunger / Q000187:drug effects / Q000502:physiology; D007328:Insulin / Q000097:blood; D008055:Lipids / Q000097:blood*; D008875:Middle Aged; D050177:Overweight / Q000097:blood / Q000178:diet therapy*; D016896:Treatment Outcome; D015431:Weight Loss / Q000187:drug effects / Q000502:physiology