Long-term body weight fluctuation in an overweight population.

Weight loss programs report such low percentages of overweight subjects who lose weight and maintain the loss that the concern arises whether these results represent anything more than baseline population weight fluctuations. In this study, weights recorded for medical purposes at two clinic visits separated by intervals of 1 to 5 years were analysed for 332 adult patients who were initially at least 20 percent over their ideal body weight. Weight change calculations for this general patient population revealed that 219 (66 percent) had increased in weight by a mean of 5.7 kg, and that 113 (34 percent) had decreased in weight by a mean of 5.3 kg. The 59 patients measured over a 5-year interval showed an 'apparent body weight loss' for 31 percent of this sub-group with a mean decrease of 7.3 kg. Weight loss studies and programs must demonstrate a rate of weight loss maintenance beyond that of a control group before attributing 'weight loss' in a population to any factor other than normal weight fluctuation.