BMI index is not the best measure of overall health

BMI Is Not The Best Indicator Of Health

I wasn't aware of debate in the health community about measuring body mass (BMI) and how it is being used as a reliable indicator of a person's health. While it has been used that way for over a hundred years, it seems to miss much, such as frame size or other issues.

Biggest problems using BMI as a health indicator

As Vance Voetberg said in an article at the Epoch times,

The BMI assessment was initially developed to evaluate the health of large populations, offering a broad perspective on the overall fitness of society. In this context, the BMI assessment generally provides accurate results. However, when applied to assess individuals, as is now the standard practice, it falls short of providing a comprehensive picture of an individual’s health status.

BMI is measured by taking a person’s weight and dividing it by the square of his or her height. The final number is categorized into five groups: underweight, normal, overweight, obese, and severely obese.

The conventional understanding defines the “normal” range as indicative of metabolic health, representing a balance between being too skinny or too fat. While this reasoning is seemingly logical, it is an imperfect and imprecise method for measuring individuals’ health and fitness.
BMI chart
Since BMI is solely based on a person’s height and weight, it provides an incomplete fitness assessment. It fails to consider crucial factors such as muscle mass, bone density, overall body composition, and racial and sex differences.

That makes sense to me. I have a couple boys who are very lean bodybuilders who show up as "obese" on the BMI scale. They're not. And they find that annoying when applying for things like life insurance.

“...a bodybuilder may have a very high BMI but be very lean because their muscle is increasing their weight, which increases their BMI,” said Chris Masterjohn, who has a doctorate in nutritional science. Therefore, BMI “is not a measurement of health at all—it is a measurement of your weight and height.”
Research shows that higher muscle mass serves as a crucial indicator of improved health and longevity, positively correlating with an increased lifespan. On the other hand, excess fat is strongly associated with a significant reduction in life expectancy.

The BMI test was initially developed for population-level assessments, not individual evaluations

“One of the key flaws is that it is not great at taking into account variability in body composition,” said Dr. Tracy Richmond, an assistant professor of pediatrics at Harvard Medical School with more than 10 years of experience conducting weight-related research.

“Individuals with higher BMIs can be healthy,” she noted, adding that using BMI alone to determine health risks can lead to overlooking individuals who may require further assessment, potentially misleading healthy individuals into believing they are overweight and misinforming others who may face serious health challenges.
“Individuals with low or normal BMIs are often given a ‘pass’ and assumed to be healthy,” Richmond noted. But people with “normal” BMI scores may have disordered eating and be at risk of anemia and micronutrient deficiencies, she added.

What is better than BMI for assessing fitness?

Margaret Ashwell... says that the waist-to-height ratio offers a valuable alternative to the BMI assessment in analyzing body composition and health. WHtR compares waist circumference to height, with the ideal ratio being less than half of a person’s height.
“WHtR is a better indicator of early health risk than BMI because it is a proxy for central adiposity,” Ashwell told The Epoch Times. “Fat stored in central depots is a risk factor for major metabolic diseases, such as Type 2 diabetes and heart disease,” she added.
This simple method, Ashwell noted, accurately identifies the problem doctors should be looking for: the accumulation of fat. And given that increased exercise and muscle are associated with a smaller waist circumference, the WHtR assessment can distinguish between fat and muscle—unlike the BMI test.

There are a couple studies that have demonstrated that weight-to-height-ratio is a much better at assessing overall health. This 2021 study in "Frontiers in Public Health" showed WHtR more accuracy for predicting high blood pressure in people with Type 2 diabetes. And this study published at the NIH showed it is a better predictor of metabolic issues than the BMI.

“The simple message of ‘keep your waist to less than half your height’ can be applied to men and women and children of all ages in all ethnic groups,” Ashwell said.

The Best Ways to Measure Health

From the article:

While the WHtR test may offer advantages over BMI, it alone does not entirely assess an individual’s health and fitness.
Although a good WHtR score can be handy, it does not delve into other important aspects, such as potential nutrient deficiencies or elevated inflammation levels.
Therefore, Masterjohn suggests additional evaluations such as body fat analysis, fasting glucose measurement, lipid profile testing, inflammation markers like C-reactive protein, and a complete metabolic panel, blood count, and urinalysis to obtain a comprehensive understanding of one’s health.
Furthermore, he recommends a functional movement screen by a physical therapist or personal trainer to preserve optimal body functionality as people age.
Read More