Physiological effects of weight cycling in female lightweight rowers.

Repeated cycles of weight loss and regain are referred to as weight cycling. It is a practice of many athletes who must achieve a low body weight. The purpose of this study was to determine whether a history of weight cycling results in sustained metabolic changes. Healthy female rowers with a history of dieting and weight fluctuation (n = 7) were compared to a control group of rowers who had never dieted (n = 7). Anthropometric and metabolic measurements were done at pre-, peak, and off-season during a 1-year period. At peak season the weight cyclers restricted their food intake and lost 4.2 +/- 1.8 kg, and subsequently regained 4.0 +/- 2.1 kg in the off-season. This was different from the controls (p = .003), who maintained a stable body weight at all times. No other group differences were observed. Resting metabolic rate (RMR) and triiodothyronine (T3) changed with time (p = .001, p = .000, respectively) in both groups, which appeared to reflect changes in fat free mass (FFM), not body weight. Long-term metabolic changes were not observed in these athletes.