Aging can be defined as a progressive decline in the ability of an organism to resist stress, damage, and disease. It is characterized by an increase in the incidence of degenerative disorders including cancer, cardiovascular disease, decreased immune function, and diabetes. The aging process proceeds at a varied rate in different individuals. Consequently, some individuals age slower than others predisposing them to long life and retention of physical and cognitive capacity promoting the sense of well being associated with healthy aging. The purpose of this study was to test whether nonagenarians have a relatively low metabolic rate when compared to younger individuals and whether this low metabolic rate is associated with lower levels of oxidative stress and less incidence of disease. In addition, we predict that older individuals will have higher levels of physical activity and this will be associated with higher physical functionality.