METFORMIN-SUSTAINED WEIGHT LOSS AND REDUCED ANDROID FAT TISSUE AT 12 MONTHS IN EMPOWIR (ENHANCE THE METABOLIC PROFILE OF WOMEN WITH INSULIN RESISTANCE): A DOUBLE BLIND, PLACEBO-CONTROLLED, RANDOMIZED TRIAL OF NORMOGLYCEMIC WOMEN WITH MIDLIFE WEIGHT GAIN.

Objective: To assess 12-month body weight (BW) and body composition changes in normoglycemic women with midlife weight gain, after dietary and pharmacologic interventions targeting hyperinsulinemia.
Methods: EMPOWIR (Enhance the Metabolic Profile of Women With Insulin Resistance; NCT00618072) was a double-blind, placebo-controlled, 12-month trial of women with >20-pound weight gain, normal glucose tolerance test, and increased area-under-the-curve insulin. Subjects (mean ± SD, 46.7 ± 6.5 years of age; body mass index, 30.8 ± 2.8 kg/m(2); 50% white) attended 4 nutrition workshops to introduce a novel carbohydrate-modified diet (CMD) and were then randomized to one of three arms for 6 months (phase 1): CMD alone (D), or in combination with metformin (M), or metformin + rosiglitazone (MR), with rerandomization of the D group to one of the active treatment arms (phase 2, months 7 through 12). Repeated measure analysis of variance was used to assess BW at baseline, 6 months, and 12 months in 32 subjects with 12-month data; paired t tests compared baseline and 12-month dual-energy X-ray absorptiometry-derived body composition.
Results: Mean (±SD) BW decreased significantly at 12 months in the M arm: 85.1 ± 8.5 kg to 79.8 ± 9.0 kg (P = .0003), with 54% of variance in weight over time explained by M treatment. Mean (±SD) percent android fat decreased significantly in the M and D arms: 53.5 ± 4.8% to 49.3 ± 7.6% (P = .010) and 52.9 ± 6.2% to 48.1 ± 8.7% (P = .021).
Conclusion: In combination with a novel carbohydrate modified diet, metformin enhanced 12-month weight loss and improved body composition in ethnically diverse normoglycemic, hyperinsulinemic women with midlife weight gain. These findings suggest that EMPOWIR's easily implemented dietary interventions, alone and in combination with pharmacotherapies that target hyperinsulinemia, merit additional investigation in larger, long-term studies.