Exam

Body Mass Index

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Body Mass Index, BMI, Body Mass Index Calculation

  • See Also
  1. Endocrine Calculations
  • Indication
  1. Used in evaluation of Obesity
  • Advantages
  1. Highly correlated to body fat
  2. May be best method available
  • Disadvantages
  1. Not accurate in muscular patients (athletes)
  2. Not accurate in pregnancy or Lactation
  • Calculation
  1. BMI = (weight in kilograms) / (height in Meters)^2
  2. BMI = (weight in lbs x 700) / (height in Inches)^2
  3. Approximating the weight at which BMI=27 (Obesity)
    1. Start with 100 pounds
    2. Add 5 pounds for every inch over 5 feet tall
    3. Add 40 pounds
    4. Example: What weight is BMI=27 for 66 inch person?
    5. Answer: 100 + (6x5) + 40 = 170 pounds
  • Interpretation
  • Adults
  1. BMI <18.5: Underweight
  2. BMI <20: Underweight or endurance athlete
  3. BMI 20 to 22: Ideal Weight
  4. BMI 22 to 25: Healthy Weight
  5. BMI 25: Mild Obesity (WHO Grade 1, 110% Ideal Weight)
  6. BMI 27: Moderate Obesity (120% of Ideal Weight)
  7. BMI 30: Severe Obesity (WHO Grade 2, 130% Ideal Weight)
  8. BMI 40: Morbid Obesity (WHO Grade 3)
  • Interpretation
  • Boys (Derived from CDC BMI charts)
  1. Approximation
    1. Overweight BMI = (Age in years) + 14
  2. Age 10
    1. Mean BMI (50%): 17
    2. At Risk BMI (>85%): 20
    3. Overweight BMI (>95%): 23.5
  3. Age 12
    1. Mean BMI (50%): 18
    2. At Risk BMI (>85%): 22
    3. Overweight BMI (>95%): 25
  4. Age 14
    1. Mean BMI (50%): 19
    2. At Risk BMI (>85%): 23
    3. Overweight BMI (>95%): 27
  5. Age 16
    1. Mean BMI (50%): 20
    2. At Risk BMI (>85%): 25
    3. Overweight BMI (>95%): 29
  • Interpretation
  • Girls (Derived from CDC BMI charts)
  1. Approximation
    1. Overweight BMI = (Age in years) + 13
  2. Age 10
    1. Mean BMI (50%): 17
    2. At Risk BMI (>85%): 20
    3. Overweight BMI (>95%): 23
  3. Age 12
    1. Mean BMI (50%): 18
    2. At Risk BMI (>85%): 22
    3. Overweight BMI (>95%): 26
  4. Age 14
    1. Mean BMI (50%): 19
    2. At Risk BMI (>85%): 24
    3. Overweight BMI (>95%): 28
  5. Age 16
    1. Mean BMI (50%): 20
    2. At Risk BMI (>85%): 25
    3. Overweight BMI (>95%): 29
  • Resources
  1. NIH Obesity Education Initiative BMI Calculator
    1. http://www.nhlbisupport.com/bmi/bmicalc.htm
  2. CDC Growth Charts (source for childhood BMIs above)
    1. http://www.cdc.gov/growthcharts
  3. CDC Body Mass Index Information
    1. http://www.cdc.gov/nccdphp/dnpa/obesity/bmi.htm
  • References
  1. Green (1994) Bright Futures, NCEMCH, p. 266