Experts Call for Overhaul of Obesity Diagnosis, Moving Beyond BMI

Leading health experts propose a two-tier system for obesity diagnosis.

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Amid rapidly rising global obesity rates, leading health experts are calling for a major overhaul in how the condition is diagnosed, pushing to move beyond the traditional body mass index (BMI) measurement toward more precise methods of assessing body fat and its impact on overall health.

Direct Measurement of Body Fat

A recent report from the Commission on Clinical Obesity, published in The Lancet Diabetes & Endocrinology on Jan. 14, advocates significant changes in how obesity is diagnosed, emphasizing the need to move beyond BMI, the traditional metric used to diagnose the condition.

The commission’s work, endorsed by 76 medical organizations, brought together nearly 60 experts in nutrition, endocrinology, and obesity, along with patient advocates, to develop new definitions that consider both clinical utility and societal perceptions.

The commission proposed a more nuanced diagnostic framework incorporating direct measurements of body fat, arguing that BMI alone is not a reliable measure of health or illness at the individual level.

The commission’s recommended methods for confirming excess fat mass and distribution include using at least one body size measurement (waist circumference, waist-to-hip ratio, or waist-to-height ratio) in addition to BMI and taking at least two body size measurements or conducting direct body fat measurement through scanning, regardless of BMI.

Relying on BMI alone to diagnose obesity is problematic, “as some people tend to store excess fat at the waist or in and around their organs, such as the liver, the heart or the muscles,” said commissioner and professor of medicine Dr. Robert Eckel from the University of Colorado Anschutz Medical Campus in a press statement.

This sort of fat distribution is associated with more health risks, including Type 2 diabetes, heart disease, some cancers, and mental health issues, than when excess fat is stored just beneath the skin in the arms, legs, or other body areas, according to researchers.

New Diagnostic Categories Introduced

The commission introduced two new diagnostic categories: clinical obesity, which occurs when obesity causes ongoing disease, and preclinical obesity, when obesity has not yet caused disease or organ problems.

Dr. Francesco Rubino, chair of the commission and a professor at King’s College London, argues for a more sophisticated understanding of obesity. “The question of whether obesity is a disease is flawed because it presumes an implausible all-or-nothing scenario where obesity is either always a disease or never a disease,” he stated in the press release.

He said that thinking of obesity only as a risk factor can “unfairly deny access to time-sensitive care among people who are experiencing ill health due to obesity alone.”

The “blanket definition” of obesity—a BMI of 30 or higher—could result in overdiagnosis and unwarranted use of medications and surgical procedures, “with potential harm to the individual and staggering costs for society,” Rubino said. A blanket definition might not account for individual variations in body composition, metabolism, and health risks.

This could lead to people being labeled as sick solely based on their BMI, even if they are otherwise healthy. Such an approach could shift the focus from overall health to weight loss, potentially overlooking other important health factors.

Overdiagnosis could also drive the unnecessary use of weight-loss medications, which can have side effects and may not be suitable for everyone. Similarly, it could increase the number of people undergoing weight-loss surgery, a major procedure with potential risks.

The commission’s report highlights a flaw in the current practice of diagnosing obesity: BMI measurements fail to capture crucial information about fat distribution and its impact on health.

“This nuanced approach to obesity will enable evidence-based and personalised approaches to prevention, management and treatment in adults and children living with obesity, allowing them to receive more appropriate care, proportional to their needs,” stated Commissioner Louise Baur, a professor at the University of Sydney in Australia, pediatrician, and renowned child and adolescent obesity researcher in the press release.