This may not seem like much, but the percentage of moderately overweight runners increased from 21% before age thirty to 30% between ages 45 to 49 (see graph below). Statistically, it appears that age-related weight gain and exercise-induced weight loss are independent, additive effects. Middle-aged runners are leaner than more sedentary men not because the processes that promote age-related weight gain are abated, but rather because exercise-induced weight loss offsets weight gain during middle age. Our findings suggest that men who maintain constant weekly distances through middle age are expected to increase total weight and waist circumference (presumably intra-abdominal fat). Running distance needs to increase annually, by 1.4 miles per week in order to compensate for the expected increase in waist circumference between ages 20 and 50. This means that runners who average 10 miles per week at age thirty should increase their weekly running distance to 24 miles by age forty if they plan to still fit into the tuxedo they bought ten years earlier. (Permission granted to anyone wishing to use the images provided here when properly cited. Williams PT. Evidence for the incompatibility of age-neutral overweight and age-neutral physical activity standards from runners. American Journal of Clinical Nutrition 1997; 65:1391-6)