Effects of a reduced-glycemic-load diet on body weight, body composition, and cardiovascular disease risk markers in overweight and obese adults1,2,3

Lowering the dietary glycemic load and increasing protein intake may be advantageous for weight management. This randomized controlled trial was designed to evaluate the effects of an ad libitum reduced-glycemic-load (RGL) diet on body weight, body composition, and cardiovascular disease (CVD) risk markers in overweight and obese adults during an initial weight-loss phase (12 wk) and a weight-loss maintenance phase (weeks 24-36). Subjects were assigned to RGL (n = 43) or low-fat, portion-controlled (control; n = 43) diet groups. The RGL group was instructed to eat until satisfied, maintaining a low carbohydrate intake during weeks 0-2 and adding low-glycemic-index carbohydrate thereafter. Control subjects were instructed to reduce fat intake and decrease portion sizes, with a targeted energy deficit of 500 to 800 kcal/d. The RGL group had lost significantly more weight than did the control group at week 12 (-4.9 and -2.5 kg, respectively; P = 0.002), but the 2 groups did not differ significantly at week 36 (-4.5 and -2.6 kg, respectively; P = 0.085). Changes in fat mass differed between the groups at week 12 (-1.9 and -0.9 kg, respectively; P = 0.016) but not at week 36 (-2.0 and -1.3 kg, respectively; P = 0.333). At the end of the study, no differences were found in responses for CVD risk markers except a larger mean change in HDL cholesterol in the RGL group than in the control group (3.8 and 1.9 mg/dL, respectively; P = 0.037). These findings provide evidence that an ad libitum RGL diet is a reasonable alternative to a low-fat, portion-controlled eating plan for weight management.