The Problem with BMI

Your BMI may influence the kind of healthcare your doctor provides . . . But because BMI doesn’t take body composition, body fat distribution, diet, or physical activity into account, it is often not an accurate measure of one's overall health state. 

. . . .

When you go to the doctor, it’s probable s/he will evaluate your health using the metric of BMI or Body Mass Index. This metric requires two units of measure, your height and your weight, and to some extent, your age. 

Healthcare practitioners prefer using this metric because it is simple and fast. 

Maybe you’ve even seen and used a BMI chart in your doctor’s office. On one axis you find your weight and on the other your height, and then you slide your finger across to the point where the two axes meet. There you will find your ideal weight range according to BMI. 

What you probably don’t know is these charts were created using actuarial statistics developed by insurance companies interested in predicting the likelihood of individuals reaching advanced age based on data from thousands of people. 

Even more surprising to learn is that the basic height to weight formula used to calculate BMI was developed nearly 200 years ago in the 1830s, though its use as a predictor of health and longevity is relatively recent (1970s). 

It was originally used to predict the approximate ideal weight of individuals, not health or longevity, but by the mid-1980s the National Health Institute (NIH) began using BMI to define obesity in the US. 

Because research suggests a high BMI is closely tied to a greater risk of heart disease, type 2 diabetes, stroke, and cancer, according to the NIH, your BMI may influence the kind of healthcare your doctor provides, such as prescribing certain drugs, recommending health screenings, and/or monitoring your weight. 

However, BMI is FAR from perfect and IT MISSES a lot. 

For starters, BMI does not show how active an individual is, what their eating habits are, how well they move, sleep, and cope with stress. In fact, some studies suggest a healthy diet can offset the higher mortality risk associated with a high BMI. 

Even more important for those of us who weight train, BMI doesn’t take into account our individual body composition, or how much lean muscle mass an individual has. 

Muscular individuals may have a high BMI but have low body fat. In fact, athletic people tend to have heavier bones and more lean muscle mass which makes their body weight and BMI higher.  And yet, greater lean muscle mass helps to ward off metabolic conditions such as heart disease and diabetes. In this case, BMI is a poor predictor of future health problems. 

Because BMI doesn’t take body composition, body fat distribution, diet, or physical activity into account at the individual level, it is often not an accurate measure of one's overall health state. 

BMI can be a useful metric to use when analyzing populations, but at the individual level, it’s a crude measure of overall health and risks to longevity. 

In short, well-being and health risks should be measured by several factors, perhaps including but definitely NOT LIMITED to BMI.