This study examined the independent and combined effects of exercise training, weight loss and changes in dietary quality on the serum lipid profile in sedentary, healthy and overweight young women. 83 women 18-25 years with body mass index>25 were randomly assigned to four groups, control (C), diet (D), exercise (E) and exercise and diet (ED). Height, weight, per cent body fat (BF%), TC, HDL-C, TG and LDL-C were measured before and after an 8-week intervention period. Subjects in the two exercise groups walked five times a week, 45 min per session, at 60%-80% of maximum heart rate (MHR). Duration and intensity of exercise were gradually increased over a 3-week period from 25 to 30 min/sessions at 60%-65% of MHR during week 1 to 45 min at 70% to 80% MHR from weeks 4 through 8. Subjects in the two nonwalking groups (C and D) reported to the exercise facility 5 days per week for 45 min of stretching and mild range of motion calisthenics. The intent was to keep heart rate below 100 beats per minute. One-way ANOVA was the statistical test (α=0.05). Relative to control group, the ED and D groups displayed a 4.2% and 4.1% reduction in body mass, 9% and 7% reduction in BF%, 29% and 26% reduction in TG. LDL-C fell by 12% in ED group. For each kg of weight loss there was a decrease of 0.05, 0.02 and 0.015 mg/dl in TC, LDL-C and TG respectively. No change of body mass occurred in E group. Exercise alone was insufficient to stimulate change in any lipid or lipoprotein measures. These results demonstrated that weight loss mostly was due to diet, because the exercise was the same in groups E and ED. The lipid profile improved and body mass decreased.