Cardiorespiratory Fitness and the Paradoxical BMI-Mortality Risk Association in Male Veterans

A high mortality risk associated with low BMI levels was observed only in moderate-fit and low-fit individuals, and not in high-fit individuals. Thus, fitness greatly affects the paradoxical BMI-mortality risk association. Furthermore, our findings indicate that lower BMI levels do not increase the risk for premature death as long as they are associated with high fitness. Thus, the paradoxically higher mortality risk observed with lower body weight as represented by lower BMI is likely the result of unhealthy reduction in body weight and, perhaps most importantly, considerable loss of lean body mass.