A recent multinational study examining a proposed change to how obesity is defined—which includes health factors besides height and weight—found that the prevalence of obesity would decrease significantly. This raises concerns that adopting these new criteria might hinder early detection and prevention of serious health conditions.
The study, published in Plos Global Public Health, involved researchers from Emory University and Johns Hopkins University in the U.S., along with institutions in Australia, China, and Peru. The research analyzed data from 56 countries, comparing obesity prevalence using current BMI criteria versus proposed criteria that require at least one health condition (such as diabetes or hypertension) to classify someone as clinically obese.
Plos Global Public Health"Obesity is a major issue, and the definitions we use impact clinical treatment, healthcare spending, disease tracking, and personal awareness of health risks," says lead author Rodrigo M. Carrillo-Larco, MD, Ph.D., assistant professor at Emory University's Rollins School of Public Health. "Understanding how any new definition affects obesity rates is crucial."
When health issues were included in the obesity criteria, prevalence dropped significantly among 142,250 adults surveyed, with some countries seeing decreases over 50%. For instance, Malawi experienced high drops (68% for men and 53% for women) under the new definition.
While the new definition might better align with current disease risk, researchers caution against quickly adopting it. They highlight potential challenges in measurement, equity, and implementation. Additionally, those no longer deemed obese could develop a misleading sense of security.
"At a population level, obesity prevalence would decrease, but this is more an artifact of stricter or more complex criteria—it's not a real reduction," says Carrillo-Larco. "If we use these new definitions, it must not diminish the importance of preventing obesity and associated diseases. Those with high BMI but no serious health issues still need preventive care, healthy diets, and weight management."