Body mass index, or BMI, is a good guideline for keeping track of your weight. Your BMI value can tell you if you are underweight, less than 18.5; healthy weight, 18.5 to 24.9; overweight, 25 to 29.9; or obese, 30 to 39.9. Since weighing more than you should increases your risk for health problems like heart disease, knowing your BMI can be an important part of taking care of yourself. If you have an amputation, however, you need to account for the weight of the missing body part to calculate your BMI. Anthropologists have figured out a good way for amputees to calculate their BMI.
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Weigh yourself and write down your weight.
Look up the percentage of body weight value for your type of amputation (see Tips). For example, if one of a man's legs was amputated, the missing leg would be 16 percent of his total body weight.
Move the decimal point 2 places to the left in the number from Step 2. For example, the value is now 0.16.
Subtract the result of Step 3 from 1. For example, 1 - 0.16= 0.84.
Divide the current weight by the result from step 4. For example, if a man weighs 160 lbs, then 160 ÷ 0.84= 194.48. This is his estimated total weight without the amputation.
Multiply the estimated total weight by 703. For example, 194.48 X 703 to get 136719.44.
Find the height in inches. For example, if a man is 6 feet 2 inches, he will multiply (6 feet) X (12 inches in a foot)= 72 inches, plus 2 is 74 inches.
Find the square of the height in inches. For example, 74 X 74= 5,476.
Divide the result from Step 6 by the result from Step 8. In the example, 136719.44 ÷ 5476= 24.97. This value is the man's BMI.