A new study shows that 54 million Americans whose BMI classes them as overweight and obese are in perfect health according to cardiometabolic measures, while 21 million whose BMI puts them in the normal category are unhealthy. Share on Pinterest Altogether, say the authors, an estimated 75 million adults in the US are misclassified as either healthy or unhealthy when BMI is used as the sole health indicator. The study provides more evidence to support the idea that a person’s body mass index (BMI = weight in kg divided by height in m2) is a flawed measure of health. In spite of this, BMI continues to be used as a yardstick for determining health status. Many employers use it to calculate workers’ health care costs, note the researchers behind the new study, who report their findings in the International Journal of Obesity. And soon, if a rule proposed by the Equal Employment Opportunity Commission (EEOC) is adopted, US employers will be allowed to charge employees up to 30% of health care costs if they fail to meet certain health criteria such as not having a BMI in the normal range (between 18.5 and 24.99). The study, led by A. Janet Tomiyama, an assistant professor of psychology at the University of California-Los Angeles (UCLA), analyzed the link between BMI and cardiometabolic health using data from the most recent National Health and Nutrition Examination Survey (NHANES). The cardiometabolic health data available in the NHANES gives measures of blood pressure, triglycerides, cholesterol, glucose, insulin resistance and C-reactive protein (a marker of inflammation).

BMI misclassifies nearly 75 million Americans as healthy or unhealthy The analysis shows nearly half of Americans whose BMI puts them in the overweight category (34.4 million people) are actually healthy according to cardiometabolic measures, as are 19.8 million whose BMI classes them as obese. The researchers also found that 15% of Americans (2 million people) whose BMI calculation is 35 or higher – thus classing them as very obese – are also healthy. Prof. Tomiyama says: “Many people see obesity as a death sentence. But the data show there are tens of millions of people who are overweight and obese and are perfectly healthy.” She says that these people would be unlikely to incur higher medical expenses and it would be unfair to charge them higher premiums based only on their BMI. The study also finds over 30% of Americans whose BMI puts them in the normal range (nearly 21 million people) are actually unhealthy according to cardiometabolic measures. Altogether, say the authors, nearly 75 million adults in the US are misclassified as either healthy or unhealthy when BMI is used as the sole health indicator.