Exercise Effect On Weight And Body Fat In Men And Women

Abstract

The role of exercise on weight, body fat, and other anthropometrics in middle-aged and older persons is not well defined, and may differ by gender. Purpose We conducted a randomized trial testing a 12-month aerobic exercise intervention vs. control on body composition in 102 men and 100 women in the Seattle, WA area. This analysis focused on effects on: weight, BMI, waist and hip circumferences, and % body fat (DEXA scan). Methods Participants were aged 40–75 years, sedentary, and healthy. The exercise intervention consisted of a facility (3/week) and home-based (3/week) 12-months moderate-intensity aerobic activity (e.g. treadmill and outdoor walking, biking), with exercise gradually increased from 30 min./d, 3 d/wk by 4 wks to 60 min/d, 6d/wk by 12 weeks and beyond). Controls received a delayed intervention. Results Among the exercisers, men averaged 370 min./wk. (102.7% of goal), and women averaged 295 min./wk. (82% of goal) of exercise. Only 2/51 men and 5/49 women dropped the exercise intervention. VO2max increased by 11% in both men and women exercisers, and decreased in controls. After 12 months, exercise intervention men lost 1.8 kg vs. 0.1 kg loss in controls (p =0.03); exercise intervention women lost 2.7 kg vs. 1.0 kg gain in controls (p = 0.009). BMI (m/kg2) decreased in exercising men (−0.5 m/kg2 vs. no change in controls, p= 0.03) and in exercising women (−1.0 m/kg2 vs. + 0.5 in controls, p = 0.004). Waist circumference decreased 2.4 cm in exercising men vs. 0.7 cm increase in controls (p=0.002), and decreased 1.1 cm in exercising women vs. 2.5 cm increase in controls (p <0.001). Male exercisers experienced a 3.2 decline in % body fat vs. 0.2 increase in controls (p <0.001). Female exercisers experienced a 2.4 decline in % body fat vs. no change in controls (p <0.001). Differences in exercise intervention effects by gender were not statistically significant. The effect of exercise on adiposity variables did not differ by age (< 55 vs 55+ years), baseline BMI (< 25.0, 25.0–29.9, 30+), or, among women, by menopausal status. Conclusions A 12-month moderate intensity aerobic exercise intervention results in significant decreases in weight, BMI, waist circumference, and percent body fat in both men and women. The slightly higher reductions in weight and BMI in women vs. men were offset by a slightly higher loss of body fat in men. Analyses are ongoing regarding the effect of exercise on intra-abdominal and abdominal subcutaneous fat (CT scan at L4-5 level). SUPPORTED BY NIH GRANT R01CA77572