(OR27-05-24) A Low- (vs High-) Glycemic Diet Promotes Greater Loss of Body Fat in African American Women With Low Insulin Sensitivity

Objectives: The aims of this study were 1) to conduct a randomized clinical trial to identify the effects of 10-wk exposure to controlled hypocaloric low glycemic (LG) vs high glycemic (HG) diets on changes on body composition in African American (AA) women with obesity, and 2) to characterize resting (REE) and total energy expenditure (TEE), and metabolic efficiency (ME), after 4-wk post-weight-loss stabilization on the respective diets.

Methods: 67 women with obesity were randomized to either HG (55% CHO, 25% protein, 20% fat) or LG (20% CHO, 25% protein, 55% fat) energy restricted diets (at 60% of estimated TEE) over 10 weeks, followed by a 4-week weight stabilization period (energy balance; all food provided throughout). S_I was measured at baseline with an intravenous glucose tolerance test (IVGTT) and minimal modeling, and women were dichotomized as having “low” or “high” S_I based on the group median.  Fat mass (FM) was assessed with bioimpedance analysis at baseline and at the end of week 10. REE, TEE, and ME were assessed with indirect calorimetry, doubly-labeled water, and a submaximal cycle ergometer test at 10, 20 and 50W of power, respectively, at baseline and during the last week of weight stabilization

Results: 50 (23 in HG group) women with an average age of 44±12 years and a BMI of 38±8 kg/m² finished the 10-week intervention, and 43 the 4-week stabilization phase. Women with low (but not high) S_I on the LG diet lost more FM than those on the HG diet group (-4.9±0.9 vs -2.1±1.0 kg, P=0.04). There was also a tendency for those in the LG diet to lose more weight (-6.6±1.0 vs -4.1±1.4 kg, P=0.076) at week 10. Women with low (but not high) S_I on the LG diet had a smaller reduction in REE (-48±30 vs -145±30 kcal/day, P=0.035) and TEE (54±59 vs -172±136 kcal/day, P=0.038) than those on the HG diet. Additionally, women randomized to the LG diet with a low S_I had less of an increase in netME at 10W and 50W compared with those with a high S_I (0.007±0.004 vs 0.014±0.01 and 0.003±0.01 vs 0.027±0.01, respectively).

Conclusions: A LG diet leads to a greater FM loss in AA women with obesity and low SI, likely by minimizing the reduction in EE that follows weight loss, both at resting and during exercise. These findings can help guide diet recommendations for this patient population.

Funding Sources: NIDDK, DRC, NORC, UAB