Effects of weight cycling in rats allowed a choice of diet

We examined the effects of weight cycling, produced by bouts of weight loss and regain, on body weight, body composition, dietary fat intake, and energy efficiency. Three groups of adult female Wistar rats were followed for 116 days: control rats (n = 10) were allowed ad libitum access to three mixed diets with protein as a constant proportion of energy and fat provided at 10, 30, and 50% of energy; cycled rats (n = 10) had four bouts of food restriction (50% of baseline intake for 10 days) and refeeding (18-20 days of ad libitum access to the 3 mixed diets); maturity controls (n = 10) were treated identically to controls during the first two cycles and identical to cyclers during the final two weight cycles. At the end of the experiment, we could identify no negative effects of weight cycling on any of the measures taken, and in fact body weight and percentage body fat were lower in cyclers than controls. Dietary fat intake was not altered by weight cycling. In summary, weight cycling did not promote body weight or body fat gain.