Obesity is associated with an increased risk for early death, heart disease and stroke, disability and several other comorbidities. Although there is concern about the potential burden on health-care services with the aging demographic and the increasing trend of obesity prevalence in older adults, evidence on which to base management strategies is conflicting for various reasons. The analytic framework for this review is based on a scoping review methodology, and was conducted to examine what is known about the diagnosis, treatment and management of obesity in older adults. A total of 492 relevant research articles were identified using PubMed, Scirus, EBSCO, Clinicaltrials.gov, Cochrane Reviews and Google Scholar. The findings of this review indicate that the current WHO (World Health Organization)-recommended body mass index, waist circumference and waist-to-hip ratio obesity thresholds for the general adult population may not be appropriate for older adults. Alternatively, weight change or physical fitness may be more useful measures of mortality and health risk in obese older adults. Furthermore, although obesity in older adults is associated with several disorders that increase functional disability, epidemiological evidence suggests that obesity is protective against mortality in seniors. Consequently, the trend toward increasing prevalence of obesity in older adults will lead to an increase in unhealthy life years and health-care costs. The findings from this review also suggest that treatment strategies for obese older adults should focus on maintaining body weight and improving physical fitness and function rather than weight loss, and that a combination of aerobic and resistance exercise appears to be the most effective strategy. In conclusion, this review demonstrates the need for more research to clarify the definition of obesity in older adults, to establish criteria for evaluating when to treat older adults for obesity, and to develop effective treatment strategies focused on functional outcomes in obese older adults.