The graph below displays the average waist line by age in middle-aged men. The data are stratified by weekly running distance: <10 miles, 10-20, 20-30, 30-40 and over 40 miles per week. Within each mileage group we have plotted the average waist line for ages <30, 30-35, 35-40, 40-45 and 45-50 years old. Average waist line appears to expand as age increased at all levels of running. The graph below displays the average BMI by age in the 18-49 years old, stratified by mileage. There is a consistent decrease in BMI with mileage across all age categories. BMI increased with age at all levels of running. The average rate of weight gain was the same in men running less than ten miles per week and those exceeding forty, about 3.3 pounds and about 3/4 inches around the waist per decade in a 6' man.