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Body Mass Index (BMI): Too Crude A Tool?

The measure still used globally for obesity actually does not measure fat.

August 24, 2014

Credit: Suzanne Tucker - Shutterstock.com

1. Body Mass Index (BMI) is a measurement of mass in the human body. However, it does not differentiate between muscle and fat.

2. The Belgian statistician Adolphe Quetelet developed the formula in the early 1800s.

3. In his 1835 book, he observed that weight is proportional to height squared and calculated a ratio of the two figures.

4. The best one can say about the concept of the body mass index, as it was later dubbed, is that it may be preferable to the alternatives.

5. BMI — which became an accepted gauge of obesity around 1972 — is simple, cheap and accurate for broad trends.

6. Health organizations such as the WHO and CDC do not reflect the amount of body fat in their definition of obesity.

7. It is difficult and expensive to calculate fatness in the human body.

8. Some people, generally with a lot of muscle, have a high BMI, but are not at risk for health problems, while some with a low BMI can be at risk. However, for the majority of people, the correlation holds.

Source: Gauge That’s Worth the Weight by Jo Craven McGinty (Wall Street Journal)

Takeaways

The best one can say about the concept of the body mass index is that it may be preferable to the alternatives.

BMI does not differentiate between muscle and fat.

Some people, generally with a lot of muscle, have a high BMI, but are not at risk for health problems.