Body mass index (BMI) has long been foundational in healthcare around the world. The simple equation (方程) of weight relative to height has been used to determine your risk for certain diseases. But researchers have been questioning the value of BMI in individual health assessment now.
BMI was never intended to measure individual health. It was developed in the early 1800s to study weight variations across entire population. "BMI is a rigid number based on old data," says Fatima Stanford, a professor at Harvard Medical School. And it's far from perfect in terms of the cutoffs (分界点) designed to indicate risk, she added.
A study estimated that more than 74 million American adults were miscategorized (被误分类) as unhealthy or healthy based on their BMI alone. Nearly half of people considered over weight and 29 percent categorized as obese were actually healthy. Thirty percent of those considered to be at a normal weight had heart issues.
Part of the problem is that BMI doesn't tell the difference between weight from fat and muscle. So bodybuilders and athletes with high muscle mass may be categorized as overweight or obese. And even among people who do have higher body fat, BMI doesn't tell physicians anything about how the fat is distributed —a key connection to disease risk.
Furthermore, BMI cutoffs are largely based on data from western populations, making it a problem to apply this measurement to the diverse American population. There's growing evidence that body composition varies from race to race. African Americans, for example, are likely to carry more fat around the hips than white Americans. A study showed that for black adults in the U.S., having a higher BMI (25 and over) did not carry the same risk of death as it did in white adults.
Regardless of the BMI category you fall into, it's important to find a healthcare provider who will look beyond that number to get a whole picture of your health. Because despite the view that people with a higher BMI have a greater risk for a number of diseases than thinner people, the research shows it's not that simple.
