Measurement Underweight Normal Normal Overweight Obesity I Obesity II Obesity III Body mass index (BMI)* <18.5 *** 18.5-24.9 25.0-29.9 30.0-34.9 35.0-39.9 40+   Below normal Athlete Healthy nonathlete Potential risk Slight risk Moderate risk High risk % body fat** Men Women <12% <18% 5-13% 12-22% 12-17% 18-22% 17-20% 22-27% 20.1-25% 27.1-32% 25.1-30% 32.1-37% >30% >37% *Data source: American College of Sports Medicine, ACSM's Guidelines for Exercise Testing and Prescription (6th ed.). Lippincott, Williams & Wilkins, 2000. **Data source: AFAA, A Guide to Personal Fitness Training. Aerobics & Fitness Association of America, 1997. ***Note: There are no recommendations for BMI for athletes.