Obesity is increasing in middle-aged adults and in elderly subjects (over 65 years), owing to the concurrence of different factors: inactivity, wrong nutritional habits, and basal metabolism and nutritional need reduction. This condition is becoming a serious problem because of the increasing numbers of the aged population all over the world. In the past, obesity was considered as a 'secondary' pathology of no medical importance in old age; but nowadays, obesity is increasingly being studied in Geriatrics too, because it causes disability and because of its quality-of-life impairment consequences. The Euronut-Seneca study has confirmed the presence of obesity in both men and women in Europe. The definition of obesity, the reference values of body mass index and obesity as a mortality factor in elderly persons are still under discussion. Even when overweight does not represent a serious problem in old age, obese elderly people are certainly at risk of disability, morbidity and mortality. This review focuses on the potential risks of overweight and obesity in the aged population.