Dietary glycemic index does not influence adaptation of resting energy expenditure during weight loss (371.7)

Abstract

It has been suggested that low glycemic index (GI) diets may help prevent weight regain following weight loss by attenuating the decline in energy expenditure that is associated with lower body weight. To determine the independent impact of dietary GI on resting energy expenditure (REE) during and after weight loss, 79 overweight and obese adults (mean ± SD; 56 ± 6 y, BMI 33 ± 2 kg/m2) were randomized to 1 of 4 provided diets differing in fat proportion (15% or 30% of energy) and GI (low, 55 or high, 88), but matched for protein and fiber contents. Food was first provided at 67% of measured weight maintenance requirements for 12 wk, then at 100% of requirements for 5 wk. Body composition and measured REE (mREE) were determined at baseline, 12 wk and 17 wk. Predicted REE (pREE) at 12 wk and 17 wk was calculated from age, sex, fat mass (FM) and fat free mass (FFM) based on a regression model developed from baseline data (R2 = 0.91, p < 0.001). Measured decreases in body weight, FM, FFM and REE over 17 wk did not differ significantly by dietary fat or GI. In the combined‐cohort, mREE was 56 ± 89 kcal/d and 44 ± 108 kcal/d lower than pREE at 12 wk (p < 0.001) and 17 wk (p < 0.01), respectively, but did not differ by dietary fat or GI‐level (12 wk: p = 0.51, 17 wk: p = 0.83). Dietary GI does not appear to attenuate the reduction in REE associated with weight loss when potentially confounding factors such as dietary protein level are controlled.Grant Funding Source: Supported by NIH grant RO1HL 57981