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Lecture Notes

One very common indicator of overweight or obesity and also of health risk is body mass index, or BMI. And that's simply defined as your body weight in kilograms divided by your height in meters squared. And this is an indication, again, of the ratio of your weight to your height, and it correlates very well with the amount of body fat, but it is not a measure of body fat. It's simple, quick, inexpensive, so it can be used in many different clinical and practical settings. But again, it's important to understand that it's not a measure of body fat, only a measure of your ratio of weight to height. So can you think of any problems with using solely a BMI to determine whether someone's at health risk because of their weight? Again, it's only an estimate of body fat, and it also doesn't provide any information about how the fat is distributed in the body, which is also an important to know for health risk. Alternatively, someone that is very muscular could have a high body mass index but not be at health risk. But the reality is is that the little error that there is there in maybe classifying someone who has lots of muscle with a higher body mass index is not nearly as big of a problem as our obesity problem. So BMI is a pretty good, quick, easy, simple measure of health risk and an indicator of overweight or obesity.