Moderately overweight seniors seem to live longer than those of average weight, according to an Australian study, although being very overweight, or underweight, actually shortened their lifespan. Dieting might not be beneficial in this age group, according to the report, published in the Journal of the American Geriatric Society. However the study also found that, regardless of weight, lack of exercise shortened lifespan, especially among women. The study of 9,200 adults aged 70-plus looked at what level of body mass index correlated with the lowest risk of death in senior citizens (for young people, the risks of being overweight or obese are well-known). Tracking the number of deaths over 10 years among volunteers aged 70 to 75 at the start of the study, researchers found that those who were overweight had the lowest overall risk of dying, especially from specific diseases including cardiovascular disease, cancer, and chronic respiratory disease. Sedentary lifestyles, however, doubled the risk of mortality for women and increased it by 25 per cent for men.