Benefits of BMI

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BMI is a useful tool for understanding where someone’s weight falls on the scale from underweight to overweight.

 

It can also help people maintain a moderate weight, which can reduce their risk for:

• type 2 diabetes

• osteoarthritis

• cardiovascular disease

• stroke

• some forms of cancer

 

As a measurement, BMI has the following benefits:

• it is easy to calculate using a scale and tape measure

• it is inexpensive to measure

• it has a strong correlation with body fat levels

• a significant amount of research shows a link between BMI and health

 

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Drawbacks of BMI

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While BMI can estimate whether a person’s weight is moderate, it has some limitations.

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While it correlates with body fat levels, BMI does not distinguish between the weight that comes from fat, muscle, and bone. Therefore, someone who is muscular could have the same BMI as someone who is overweight.

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Additionally, the proportion of muscle, fat, and bone in the body typically changes as people age, especially among females.

• The average female loses roughly 13 pounds of muscle and bone between the ages of 25 and 65, while belly fat increases to four times its previous amount.

• A 70-year-old female who still weighs what she did when she was 25 may, therefore, have a BMI that falls in the healthy range despite having a much larger percentage of body fat.

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A high body fat percentage has an adverse effect on health.

• People with a “normal” BMI but a high percentage of body fat had a higher risk of developing metabolic syndrome.

• People with excess fat around the belly had a higher risk of mortality.

• Some postmenopausal women with a body fat percentage of 35%, considered a sign of obesity, may not fall in the “obese” category according to their BMI.

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As such, BMI alone may be a misleading measurement of someone’s overall health, particularly for people who are very muscular, are peri- or postmenopausal, or have abdominal fat but are otherwise a moderate weight.