II. Indication
- Used in evaluation of Obesity
 
III. Advantages
- Highly correlated to body fat
 - May be best method available
 
IV. Disadvantages
- Not accurate in muscular patients (athletes)
 - Not accurate in pregnancy or Lactation
 
V. Calculation
- BMI = (weight in kilograms) / (height in Meters)^2
 - BMI = (weight in lbs x 700) / (height in Inches)^2
 - Approximating the weight at which BMI=27 (Obesity)
- Start with 100 pounds
 - Add 5 pounds for every inch over 5 feet tall
 - Add 40 pounds
 - Example: What weight is BMI=27 for 66 inch person?
 - Answer: 100 + (6x5) + 40 = 170 pounds
 
 
VI. Interpretation: Adults (Non-Asian Descent)
- BMI <18.5: Underweight
 - BMI <20: Underweight or endurance athlete
 - BMI 20 to 22: Ideal Weight
 - BMI 22 to 25: Healthy Weight
 - BMI 25: Mild Obesity (WHO Grade 1, 110% Ideal Weight)
 - BMI 27: Moderate Obesity (120% of Ideal Weight)
 - BMI 30: Severe Obesity (WHO Grade 2, 130% Ideal Weight)
 - BMI 40: Morbid Obesity (WHO Grade 3 Obesity or Severe Obesity)
 
VII. Interpretation: Adults (Asian Descent)
- BMI <18.5: Underweight
 - BMI 18.5 to 23: Healthy Weight
 - BMI 23 to 27.5: Overweight
 - BMI 27.5 to 32.5: Class 1 Obesity
 - BMI 32.5 to 37.5: Class 2 Obesity
 - BMI >37.5: Class 3 Obesity (Severe Obesity)
 
VIII. Interpretation: Boys (Derived from CDC BMI charts)
- Approximation
- Overweight BMI = (Age in years) + 14
 
 - Age 10
- Mean BMI (50%): 17
 - At Risk BMI (>85%): 20
 - Overweight BMI (>95%): 23.5
 
 - Age 12
- Mean BMI (50%): 18
 - At Risk BMI (>85%): 22
 - Overweight BMI (>95%): 25
 
 - Age 14
- Mean BMI (50%): 19
 - At Risk BMI (>85%): 23
 - Overweight BMI (>95%): 27
 
 - Age 16
- Mean BMI (50%): 20
 - At Risk BMI (>85%): 25
 - Overweight BMI (>95%): 29
 
 
IX. Interpretation: Girls (Derived from CDC BMI charts)
- Approximation
- Overweight BMI = (Age in years) + 13
 
 - Age 10
- Mean BMI (50%): 17
 - At Risk BMI (>85%): 20
 - Overweight BMI (>95%): 23
 
 - Age 12
- Mean BMI (50%): 18
 - At Risk BMI (>85%): 22
 - Overweight BMI (>95%): 26
 
 - Age 14
- Mean BMI (50%): 19
 - At Risk BMI (>85%): 24
 - Overweight BMI (>95%): 28
 
 - Age 16
- Mean BMI (50%): 20
 - At Risk BMI (>85%): 25
 - Overweight BMI (>95%): 29
 
 
X. Resources
- NIH Obesity Education Initiative BMI Calculator
 - CDC Growth Charts (source for childhood BMIs above)
 - CDC Body Mass Index Information
 
XI. References
- Green (1994) Bright Futures, NCEMCH, p. 266