Myth: BMI is a an accurate marker of health.
Body mass index, or BMI, a measure of weight relative to height, was originally intended for statistical, not individual, purposes, but became the standard method used to define who’s a “healthy” weight versus who’s “overweight” or “obese.”
Over the past decade, though, exercise scientists, doctors, and other experts have come to realize that’s a problem. BMI doesn’t specifically measure excess body fat, nor does it account for factors like age and muscle mass, which are crucial to health. This means that people like elite athletes can be defined as obese based on high BMI, even if they’re at peak health.
“It’s just a measure of weight to height, not a measure of health,” Kelly Coffey, a certified personal trainer, previously told Insider.
Now the field is looking toward other ways of determining baseline markers of health. One such alternative is waist circumference, since many of the negative health affects of obesity are linked to high levels of abdominal fat. Several studies have documented a link between high amounts of abdominal fat and an increased risk of heart disease and diabetes, for example.
Others argue that health shouldn’t be based on weight, body fat, or body shape at all, and really on health behaviors like physical activity, mental health care, and sleep.