Objective: This study was designed to measure the influence of diet, exercise or both on serum lipids and lipoproteins in obese women. Methods: Obese subjects were randomly divided into one of four groups: diet alone (1,200 -1,300 kcal/day, NCEP, Step I), exercise alone (five 45 minute sessions per week at 78.4 Ϯ 0.5% maximum heart rate), exercise and diet, and controls. Maximal aerobic power, body composition, diet, serum lipids and lipoproteins were measured in all subjects at baseline and after a 12-week intervention period. Subjects included 91 moderately obese (45.6 Ϯ 1.1 y, body mass index 33.1 Ϯ 0.6 kg/m 2 ) and 30 nonobese (43.2 Ϯ 2.3 y, body mass index 21.4 Ϯ 0.34 kg/m 2 ) women who were recruited from the surrounding community. Independent t tests were used to compare obese and nonobese subjects at baseline. The 12-week intervention data from the obese groups were analyzed using a 4 ϫ 2 repeated measures ANOVA design. Results: Cross-sectional comparisons at baseline showed obese subjects had significantly higher total cholesterol, triacylglycerol, total cholesterol/HDL-C and LDL-C values and lower HDL-C values. Prospective results showed that subjects in diet and exercise and diet lost 7.8 Ϯ 0.7 and 8.1 Ϯ 0.6 kg body mass, with no significant change for exercise relative to control. Serum cholesterol and triacylglycerol improved in both diet and in exercise and diet after 12 weeks of intervention, and was most strongly related to weight loss. Conclusion: Weight loss is the most effective means of reducing lipid and lipoprotein risk factors in obese women
