BMI still shows overweight accurately

For many years, body mass index (BMI) has been used by physicians as the main tool for detecting obesity. However, the question is increasingly raised: can it be considered reliable if it does not distinguish between fat, muscle and bone? Health commissions even advise confirming the diagnosis with additional measurements. However, a fresh analysis from the USA shows that in most cases BMI is sufficient.

Specialists at Johns Hopkins University checked data on 2,225 American adults aged 20 to 59 years. The information was obtained as part of the National Nutrition and Health Survey for 2017-2018. Participants were measured not only for height and weight, but also for waist circumference and body fat percentage using the precise DEXA method – a whole-body X-ray scan.

It turned out that among those whose BMI indicated obesity, in 98.4% of cases, there was actually excess fat. This was true for both men and women, of all ages and ethnic groups. Even when waistline or fat percentage confirmation is added to the BMI, the figure hardly changes – 39.1% have obesity versus 39.7% for one BMI.

BMI was adjusted slightly for ethnicity – a BMI of 30 or higher was considered borderline for most, and 27.5 for Asian participants. In any case, the picture was stable: BMI accurately reflected the presence of excess fat.

According to the authors, in reality, cases where high BMI is not associated with obesity are rare. It can be, for example, professional athletes with large muscle mass. But such people are a minority.

It is also important that measuring fat percentage in clinics is a costly and technically challenging endeavor. Therefore, BMI remains a convenient, affordable and, as this work has shown, accurate reference point in most cases.

To summarize: most people simply do not need additional methods to confirm obesity. BMI is still a reliable aid in the fight for health.