The prevalence of overweight and obesity in the elderly has become a growing concern. Recent evidence indicates that in the elderly, obesity is paradoxically associated with a lower, not higher, mortality risk. Although obesity in the general adult population is associated with higher mortality, this relationship is unclear for persons of advanced age and has lead to great controversy regarding the relationship between obesity and mortality in the elderly, the definition of obesity in the elderly, and the need for its treatment in this population. This article examines the evidence on these controversial issues, explores potential explanations for these findings, discusses the clinical implications, and provides recommendations for further research in this area.