Body composition, maximal aerobic power (VO2 max), resting metabolic rate (RMR), and lipolytic activity of abdominal adipocytes were measured in 20 women (body mass index [BMI] = 33.5) during 14 wk of exercise training (4 h/wk at 60% of VO2 max) and dietary restriction (840 kcal/d). Frequent dieters (yo-yo) and women without a dietary history (non-yo-yo) were matched into the following groups: diet-exercise yo-yo (DE-Y), diet-exercise non-yo-yo (DE-NY), and diet-non-yo-yo group (D-NY). After 14 wk significant differences in weight loss and fat loss were revealed between D and DE groups but not between yo-yo and non-yo-yo dieters. RMR decreased in all groups but there was a significantly smaller decline after 14 wk for the diet-exercise groups. No effects of frequent dieting or exercise on basal and stimulated lipolytic activity were observed.