Thirty-seven overweight/obese (BMI: 25-35 kg/m2), premenopausal women that were randomly assigned to either an ad libitum low-carbohydrate (LC) (20% CHO, 30-40% protein, 30-40% fat), or an ad libitum low-fat (LF) (55-60% CHO, 15-20% protein, 20-25% fat) diet.All subjects were given weekly menus matching their assigned macronutrient requirements to aid in meal planning and dietary compliance. Baseline and post-diet measures included height, weight, body composition (DXA), blood lipids [total cholesterol (TC), HDL, LDL, and triglycerides (TG)], and plasma insulin levels. There were no significant group differences in any of the above-listed variables prior to the study. Nineteen women completed the 6-wk study (LC=11, LF=8). Compliance to the diets was adequate as indicated by weekly 24-hr recalls and daily urinary ketone levels. Both groups lost a significant amount of weight and body flat, (P<0.05); and weight and body fat losses were not significantly different between the groups. All groups experienced similar decreases in TG, TC, LDL, HDL, and insulin levels. These results indicate a LC diet is no more effective than a LF diet in promoting favorable changes in body weight, body composition, blood lipids and insulin levels. / Department of Family and Consumer Sciences