Short-term studies indicate that intentional weight loss among obese persons significantly improves physiologic variables. Hence, it is logical to conjecture that intentional weight loss would lead to long-term benefits and increased longevity. Herein, we review recent epidemiologic studies that investigate the weight loss-mortality association using a conservative analytic approach that included distinguishing between intentional and unintentional weight loss, adjusting for potential confounders, and excluding unhealthy subjects. On balance, results indicate that intentional weight loss appears to neither increase nor decrease mortality rate. Discussion focuses on the problems of addressing this important public health question with observational data. © 2001 Elsevier Science Ltd.