The formula to calculate BMI requires information about a person's height in meters and weight in kilograms. For weight in pounds and height in inches, there is a different formula, but due to rounding, it may not produce the exact same results.
There are some concerns related to BMI that mostly have to do with the fact that fat and lean muscle tissue are not considered in the formula. For example, a man who is an athlete may have a higher BMI calculation than a man who never leaves his desk at the office and is overweight. Of course, you would not say that the athlete is overweight - but he is muscle bound, and muscle weighs more than fat.
Another situation that may cause a misleading BMI is the calculation for a tall and lean person. The extra height of the individual comes with extra weight. This might skew the BMI and make it appear high even if the person is relatively lean. Also, as a person ages they may lose height, so the BMI may be increased without any significant change in the person's weight.
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