(30-09-07) An 18-mo randomized trial of a low-glycemic-index diet and weight change in Brazilian women1,2,3

Rosely Sichieri, Anibal S Moura, Virginia Genelhu, Frank Hu and Walter C Willett
1 From the Department of Epidemiology, Institute of Social Medicine (RS), the Department of Physiology, Institute of Biology (ASM), and the Department of Clinical and Experimental Medicine (VG), State University of Rio de Janeiro, Rio de Janeiro, Brazil; and the Department of Nutrition, Harvard School of Public Health, Cambridge, MA (FH and WCW)
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.
Design: 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 35?40 units (40 compared with 79) during all 18 mo of follow-up, and the carbohydrate intake from energy remained at 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.

Fonte: AJCN

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