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Body Mass Index (BMI) and % Fat Recommendations
Research studies show a relationship between Body Mass Index (BMI), which is equal to wgt in kg/height in meters squared (kg/m 2) and health and mortality. The disease risk for Type 2 diabetes, high blood pressure, coronary artery disease and premature death increases at a BMI above 25 kg/m2. In addition, a waist circumference of greater than 34.5 inches in women and 40.0 inches in men is also associated with an increased risk. This has resulted in the following classification of disease risk based on BMI and waist circumference.
Category |
BMI |
Disease Risk (Waist Circumference)
|
Men <40 in / Women <35 in
|
Men > 40 in / Women > 35 in
|
Underweight |
<18.5 |
- |
- |
Normal weight |
18.5 - 24.9 |
- |
- |
Overweight |
25 – 29.9 |
Increased |
High |
Obese I |
30 – 34.9 |
High |
Very High |
Obese II |
35 – 39.9 |
Very High |
Very High |
Obese III |
≥ 40 |
Extremely High |
Extremely High |
BMI is a good, reliable measure to use in large health studies. However, it is not highly accurate on an individual basis. It tends to overestimate body composition in those with larger musculoskeletal systems and to underestimate body composition in those with small musculoskeletal systems. About 1 out of 4 individuals are misclassified using BMI. In other words, if 4 individuals are classified as Overweight, 3 would actually be overweight, but 1 of them would not be. Therefore, an actual measurement of %body fat is recommended on an individual basis.
Based on the relationship between BMI and %fat, we recommend following categories for % body fat:
Gender |
Age |
Very Lean |
Normal |
Overweight |
Obese |
Male |
20-39 yrs |
< 8% |
8 – 19% |
20 – 24% |
≥ 25% |
|
40-59 yrs |
< 11% |
11 – 21% |
22 – 27% |
≥ 28% |
|
60-79 yrs |
< 13% |
13 – 24% |
25 – 29% |
≥ 30% |
Female |
20-39 yrs |
< 21% |
21 – 32% |
33 – 38% |
≥ 39% |
|
40-59 yrs |
< 23% |
23 – 33% |
34 – 39% |
≥ 40% |
|
60-79 yrs |
< 24% |
24 – 35% |
36 – 41% |
≥ 42% |
Problems with BMI
BMI is a good, reliable measure to use in large health studies. However, it is not highly accurate on an individual basis. It tends to overestimate body composition in those with larger musculoskeletal systems and to underestimate body composition in those with small musculoskeletal systems. About 1 out of 4 individuals are misclassified using BMI. In other words, if 4 individuals are classified as Overweight, 3 would actually be overweight, but 1 of them would not be. Therefore, an actual measurement of %body fat is recommended.
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