"Yo-Yo" vs. Cyclical DietingI wonder if we should distinguish typical yo-yo style dieting (characterized by repeated failed attempts at fat loss) from more controlled cyclical dieting approaches. There are perfectly good (and possibly even healthful) reasons why some people might want to have cyclical weight fluctuations. The best example I can think of would be bodybuilders; most bodybuilders have distinct "cutting" (weight loss) and "bulking" (weight gain) cycles.This is mostly due to the amount of time (not to mention the extra food) required for significant muscle growth, which necessitates accepting a certain amount of fat gain along with the muscle. Even with the best diet, gains of about half fat and half muscle are considered extremely good. As a result, bodybuilders need to have a specific phase of "cutting" or "leaning out."Over time, this produces a cyclical weight change that could be called "yo-yo dieting." I haven't read any papers discussing the health of this approach, but (drug-free) bodybuilders, unlike chronic dieters , have never really been identified as anything but healthy. My gut is that overdoing the "bulk" phase is much more harmful than aggressively dieting, owing to all the problems related to overeating-- insulin resistance, heart disease, and arthritis.The biggest difference between (successful) bodybuilders and yo-yo dieters is, of course, that they have a lower body fat percentage across the board. Another yo-yo dieting group of athletes are wrestlers, who often crash diet immediately before matches in order to make a weight class. This might be a little closer to crash dieting (especially with its focus on water weight), and certainly much more unhealthy than what bodybuilders do.Kajerm 20:37, 9 October 2006 (UTC) (Good God, I'm long-winded.)