Many people have been there: You go to the doctor’s office, get your blood pressure, height, and weight taken, and the doctor relays the unfortunate news: Your BMI is too high, and you need to lose weight. Adults can measure their BMI by taking their body weight in pounds, dividing that value by the square of their height in inches, and multiplying the result by 703. Or check out the CDC’s BMI calculator if math isn’t your thing.
Below 18.5 is underweight18.5 to 24.9 is normal25 to 29.9 is overweight30 and over is obese
If this formula seems complicated and somewhat arbitrary, that’s because it is. And many experts have started to question BMI’s accuracy and usefulness. In fact, BMI is far from perfect, and as the years have passed, more and more science has emerged that reveals the flaws of this approach. Before delving into what exactly those imperfections are, it’s important to understand not only BMI’s history but also what your BMI number suggests about your health — and why you shouldn’t necessarily jump into panic mode if your doc says your number is too high. As more people became more overweight, and the health risks associated with being overweight became clearer, epidemiologists around the world began using Keys’s body mass index approach as a way to track disease risk factors in the general population.
High BMI and Chronic Disease
High BMI and COVID-19
Groups for Which BMI May Be Inaccurate
BMI is not always the best measure of body fat and overall health, especially if you’re in any of the following groups:
Asian people The BMI scale is not a good measurement for individuals who are Asian, who may see increased health risks before their height and weight calculation qualifies as overweight (BMI of 25 or higher).As the American Heart Association points out, Asians are more likely to hold fat around their waistline, and this abdominal (called “visceral”) fat is especially dangerous.Because of this, doctors are encouraged to use a different BMI scale for Asians, with lower BMI cutoff points.Athletes People who are extremely active have heavier bones and more lean mass (think muscle), resulting in higher body weights and higher BMIs, according to a previous study.But lean muscle mass can actually increase metabolism, as well as help ward off conditions like heart disease and type 2 diabetes, according to another study.Thus, an athlete with a high BMI may not necessarily be unhealthy.Women who are pregnant or nursing Women typically have a higher body weight and body fat percentage when nursing or pregnant, per the CDC. This is so they can supply nourishment to the baby; it’s not an indication of long-term health risks.Nonpregnant women Compared with men, women generally have a higher percentage of body fat, according to research.People over age 65 A BMI of less than 23 in people older than 65 is associated with a higher health risk. And according to a previous meta-analysis, a BMI of 27 is the best in terms of decreased risk of mortality among this age group.The reason for this is not fully known, but most likely it’s multifactorial. Those with a higher BMI tend to carry more pounds of muscle compared with those with a lower BMI, which has a protective effect in terms of overall functionality, fall risk, and overall immunity.
The agency also points out that BMI doesn’t measure excess body fat, which may be a better indicator of your health state. Think of it this way: When you step on the scale, the number recorded (which is used to calculate your BMI) doesn’t account for how your body weight is composed or where on your body it’s distributed.
“There is definite truth that the BMI was tested and validated in a white male population,” says Sara Bleich, PhD, a professor of public health policy at the Harvard T.H. Chan School of Public Health in Boston. Yet Dr. Bleich explains that BMI is still useful as a tool because of the way it has evolved over time. “If BMI were only used in its original form and not changed, then we’d have to worry,” says Bleich. “There are so many different studies that have looked at elevated BMI risk in many different populations, and what it uniformly shows is that a higher BMI is bad for you. A major challenge is that, statistically, it’s normal in this country to be overweight, but each day when you’re walking around with excess weight, it’s increasing your risk for chronic conditions, and that’s true no matter [your race],” she says.
It’s common for doctors and the general public to measure BMI, but the question, then, is this: Is there a better, more comprehensive approach to help paint a picture of your health using measurement tools? Here are some measurements that are commonly used alone or combined with BMI.
Waist Circumference
Waist-to-Height Ratio
Waist-to-Hip Ratio
Body Fat Percentage
Larson prefers waist circumference and waist-to-hip ratio for health risk screening. “I think the best way to increase BMI accuracy is to add waist circumference and waist-to-hip ratio to the mix,” she says.
An account of all factors— including your personal and family health history — as well as more detailed body measurements in addition to BMI provides a better indicator of your present and future health. Additional reporting by Moira Lawler and Jessica Migala.
