Lawrence Berkeley National Laboratory

Background: Body weight increases with aging. Short-term, longitudinal exercise training studies suggest that increasing exercise produces acute weight loss, but it is not clear if the maintenance of long-term, vigorous exercise attenuates age-related weight gain in proportion to the exercise dose. Methods: Prospective study of 6,119 male and 2,221 female runners whose running distance changed less than 5 km/wk between their baseline and follow-up survey 7 years later. Results: On average, men who ran modest (0-24 km/wk), intermediate (24-48 km/wk) or prolonged distances (>_48 km/wk) all gained weight throughage 64, however, those who ran ?48 km/wk had one-half the average annual weight gain of those who ran <24 km/wk. Age-related weight gain, and its reduction by running, were both greater in younger than older men. In contrast, men s gain in waist circumference with age, and its reduction by running, were the same in older and younger men. Women increased their body weight and waist and hip circumferences over time, regardless of age, which was also reduced in proportion to running distance. In both sexes, running did not attenuate weight gain uniformly, but rather disproportionately prevented more extreme increases. Conclusion: Men and women who remain vigorously active gain less weight as they age and the reduction is in proportion to the exercise dose.