The question of whether intentional weight loss increases the longevity of obese individuals is important, given the high prevalence of obesity and co-morbidities in industrialized countries, and the high prevalence of intentional weight loss in such populations. A number of studies suggest that both weight loss and weight fluctuation are associated with increased mortality. Factors such as smoking status and pre-existing illness, however, have to be considered in relation to these findings. A study controlled for smoking status and pre-existing illness, found that intentional weight loss by overweight, white, US women, consistently reduced mortality in those with obesity related co-morbidities. An Indian study, involving individuals with previous myocardial infarction, found that dietary intervention reduced mortality substantially. Those losing > 5 kg had the greatest reduction in both total and cardiovascular mortality. In both the above studies, weight loss was approximately 10% of initial body weight. Preliminary evidence suggests that modest intentional weight loss is associated with increased longevity in individuals with co-morbidities.