Researchers Just Discovered a More Accurate Measure Than BMI—Here's Why They Say It's Better

With each passing year, we're learning more and more about the complex way genetics, lifestyle factors and social determinants of health interact to play a role in human health, longevity and body weight. Mental and physical wellness is about so much more than simply telling an individual to "eat less and move more."

Assessing someone's well-being by their weight or body mass index (BMI) has been shown to be not completely accurate or comprehensive. Yet, the outdated measure of BMI—which is a simple equation of weight relative to height—is still the individual health assessment doctors track and turn to to try to determine if a patient qualifies for certain treatments.

A May 2016 study in the International Journal of Obesity found that even though more than 74 million American adults were classified as "unhealthy" or "healthy" based on BMI alone, nearly half of those who fell under the "overweight" umbrella and 29% of those defined as "obese" were actually metabolically healthy. (That means their blood pressure, cholesterol levels and blood sugar all fell within the "normal" range.) At the same time, 30% of individuals considered "normal weight" had metabolic or heart health challenges.

There must be a better way to assess risk for disease. And researchers involved in a new article published March 22, 2023 in the European Heart Journal believe they found it. Waist-to-height ratio appears to be a more accurate estimation of heart disease risk, they suggest.

What This BMI Study Found

To come to this conclusion, an international team of scientists crunched the numbers from data for 8,400 people who had been diagnosed with heart failure and "reduced ejection fraction," a condition that involves a heart that struggles to pump enough blood throughout the body. These individuals were originally taking part in a clinical trial to appraise the effectiveness and safety of a heart medication. Along the way, the original researchers tracked the patients' weight, body size and additional heart disease risk factors, including:

• Age
• Gender orientation
• Blood pressure
• Heart function
• Blood levels of natriuretic peptides (hormones released by the heart when it's under pressure)

Looking at all of these details and the eventual heart health outcomes, they believe that waist-to-height ratio is a more fair reflection of disease risk than BMI. This can help approximate the amount of belly fat (called visceral fat) in and around vital organs that play a role in our health and longevity, like the liver, the scientists claim.

Those who had the highest waist-to-height ratio—meaning that they carried a higher ratio of weight near their midsection than, say, their hips— had 39% higher risk for being hospitalized later due to complications with heart failure than those with lower levels of fat around their midsection.

The United Kingdom's National Institute for Health and Care Excellence recently recommended that waist-to-height ratio should replace the BMI. "Keep your waist circumference to less than half your height," they advise residents.

"BMI is a poor reflection of body composition because it does not adjust for muscle or fat but rather weight as a whole," says Stephan von Haehling, MD, Ph.D., a cardiologist with University of Gottingen Medical Center in Germany, in a related editorial in the same European Heart Journal.

The Bottom Line

While BMI might be ever so slightly more useful to look at the population level, it's often extremely off base for individuals. (Case in point: Ashley Graham revealed to British Vogue in 2017 that she was declared "morbidly obese" by BMI standards, even when other health biometrics were perfectly healthy.)

This new study proposes that keeping tabs on weight-to-height ratio might be a more valid measure of health—but here, they only studied heart health. And it's also worth noting that they only studied individuals who already had been diagnosed with heart failure. Does this hold true among those who are diagnosis-free? How about people of different backgrounds; geographically, socioeconomically or otherwise? Much more research is required about how we might eventually be able to predict future disease risk.

Until we know more, your best bet is to try to integrate as many lifestyle choices as possible that promote a well-balanced menu, physical activity, stress management, social connections and quality sleep. Time and time again, these details—rather than a certain number—prove to be the features of truly healthy life.

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