Humans diverge from our close relatives (chimpanzees/ bonobos) in high survivorship to menopause and decades of postmenopausal longevity. Evolutionary perspectives see the human postmenopausal lifespan as a species-typical life history trait that has evolved by selection for maintenance of physiological systems at increasingly older ages. Maintenance of body composition and low rates of metabolic and cardiovascular disease should thus characterize the early postmenopausal period, which they do in hunter-gatherers despite little access to Western medicine. In contrast, women in industrialized society tend to increase body fat and have high rates of metabolic syndrome during the early postmenopausal period; as such, the prevailing medical view is that menopause itself increases disease risk. Physical activity relates to metabolic health, and may help explain this disparity: older hunter-gatherers tend to be highly active, while women in industrialized society tend to be increasingly sedentary with age. Within the framework of evolutionary medicine, the present study investigates the effects of physical activity on body composition and resting energy expenditure (REE) in postmenopausal women from San Diego. Low REE, low fat-free mass and high body fat are risk factors for metabolic syndrome; exercise may increase fat- free mass and REE, and lower body fat. Long-term, habitually-active women were compared to sedentary women who completed a 16-week training program. In this sample, active women tended to have less body fat, but did not have higher fat-free mass or REE. Despite strength and aerobic fitness gains, the training program failed to increase fat-free mass and REE. Comparison of this study's subjects to published results from highly-trained athletes and data on hunter-gatherers suggests that even the active women in the present sample were rather sedentary, consistent with the idea of an intensity threshold for the effects of exercise on metabolism. Additionally, the training program's lack of effect is consistent with some past studies, supporting the idea that the metabolic response to exercise is muted with age and sedentary behavior. Thus, both the intensity and timing of exercise may be important to reducing metabolic disease risk, possibilities that can be evaluated by continuing to study postmenopausal health from the perspective of evolutionary medicine

Postmenopausal women experience an age-related decline in resting energy expenditure (REE), which is a risk factor for energy imbalance and metabolic disease. Exercise, because of its association with greater lean tissue mass and other factors, has the potential to mediate REE decline, but the relation between exercise and REE in postmenopausal women is not well characterized. This study tests the hypothesis that exercise energy expenditure (EEE) is positively associated with REE and can counter the effects of age and menopause. It involves a cross-sectional sample of 31 healthy postmenopausal women (aged 49-72 years) with habitual exercise volumes at or above levels consistent with current clinical recommendations. Subjects kept exercise diaries for 4 weeks that quantified exercise activity and were measured for body composition, maximal oxygen uptake, and REE. Multiple regression analysis was used to test for associations between EEE, age, body composition, and REE. There was a significant positive relation between EEE and lean tissue mass (fat-free mass and fat-free mass index). The relation between REE and EEE remained significant even after controlling for lean tissue mass. These results support the hypothesis that exercise is positively associated with REE and can counter the negative effects of age and menopause. They also indicate a continuous relation between exercise and REE across ranges of exercise, from moderate to high. Exercise at levels that are at or above current clinical guidelines might, in part, ameliorate the risk for energy imbalance and metabolic disease because of its positive relation with REE.