In recent years, the usefulness of body mass index, or BMI, has been debated, since the measurement compares height and weight and may classify muscular people as overweight when they are in fact healthy. A new study from University of Bristol, however, suggests BMI is a useful way of determining a person's overall health.
To test this, the researchers ran a variety of tests - including an X-ray scan that measures fat and lean tissue and a BMI calculation - on 2,840 young people who were either 10 or 18 years old. They found that the BMI tests offered similar information and conclusions as the more complex X-ray exam, suggesting BMI can measure future health risks like heart disease, high blood pressure, and high cholesterol.
"We found that trunk fat is the most damaging to health, but that simple BMI gives very similar answers to more detailed measures," Dr Joshua Bell, an epidemiologist at the University of Bristol who lead the study, said in a statement.
As Bell noted, the researchers found tests that measure specific areas of fat, like around a person's stomach or legs, offered similar results as a BMI test, which is calculated by dividing a person's total weight by their height.
The researchers found that people who had high BMIs also had high blood pressure and high cholesterol, suggesting that BMI is an accurate measure for determining the overall state of a person's health.
Prior research has suggested BMI doesn't offer a complete enough picture of a person's health.
In 2017, the Mayo Clinic released the Body Volume Indicator (BVI) as a BMI alternative. The BVI uses abdominal fat, not overall weight and height, to determine health.
More specifically, BVI compares the volume of your abdomen to the volume of your body overall, since belly fat has been proven a major indicator of health, according to Harvard Medical School.
A 2007 study also found that fitness level was a more important factor than BMI when determining the mortality rates of veterans with type 2 diabetes, suggesting BMI isn't a comprehensive way to determine health. In reality, factors like ethnicity and muscle mass can skew a person's BMI, so tests that target blood pressure and cholesterol could be more helpful.
"Their BMI puts them in the obesity range. And yet on every level that we look at, their health is actually quite good," Dr Scott Kahan, the director of the National Centre for Weight and Wellness, explained to WebMD about certain overweight people.
"Their cholesterol and blood pressure are excellent. Their blood sugar is excellent. They don't seem to have any health effects associated with their excess weight."
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