Purpose of reviewTo investigate emerging data on the relationship between obesity, increased morbidity and mortality, and decreased function in the elderly. To examine what is known about the effectiveness of interventions, and how treatment might be improved.Recent findingsObesity is a common problem in the elderly, although its prevalence decreases in extreme old age. Decreased physical activity and decreased energy expenditure with ageing predispose to fat accumulation and fat redistribution. Reduction in muscle mass (sarcopenic obesity) is an important determinant of physical function and metabolic rate. Chronic inflammation and endocrine changes contribute to the changes in metabolism and body composition that accompany ageing, and are potential therapeutic targets. Body weight and body mass index are imperfect indicators of risk from obesity. The focus of treatment should be on reduction of intra-abdominal fat and preservation of muscle mass and strength. A number of recent studies have confirmed the effectiveness of exercise interventions in the elderly. Progressive resistance training, rather than endurance exercise, may be more effective in many cases. Reduced function and decreased quality of life accompany development of the complications of obesity such as diabetes and vascular disorders. There is considerable scope to impede the development of these complications in the elderly with lifestyle interventions.SummarySarcopenic obesity, with accumulation of intra-abdominal fat, is a major determinant of health status in the elderly. As in the younger population, prevention and treatment programmes have the potential to decrease the impact of diabetes, vascular disease, and other complications of obesity.