This study examined the relationship of dieting history to resting metabolic rate, body composition, and subsequent weight loss in 50 obese women. A preliminary study showed that the women were able to report with satisfactory reliability the number of diets in which they had engaged (mean = 4.9 +/- 0.5), as well as the total weight loss resulting from these diets (mean = 55.9 +/- 6.0 kg). We found no evidence that weight cycling, as measured by either of these variables, was associated at baseline with a reduced resting metabolic rate or an increased percentage of body fat. Nor did we find that weight cycling was associated with smaller weight losses in a prospective trial in which subjects were treated by very-low-calorie diet and behavior therapy. The clinical implications of these findings are discussed, as are the methodological problems encountered in conducting research on this topic.