A new approach to defining obesity could help physicians better determine which patients need more intensive treatment by focusing on the effects of excess adiposity on organs and tissues rather than relying primarily on whether a person meets a set of metabolic risk thresholds.

In a new review published in The Journal of Clinical Endocrinology & Metabolism, researchers from LSU’s Pennington Biomedical Research Center examine the concept of “metabolically healthy obesity” and argue that a newer framework distinguishing preclinical obesity from clinical obesity provides a more biologically grounded and clinically actionable approach.

The review, “Does Metabolically Healthy Obesity Really Exist: Going Toward New Definitions,” was authored by Dr. Christian Rodriguez, a postdoctoral researcher, and LSU Boyd Professor Dr. Eric Ravussin. The paper examines how the traditional classification of metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUO) has influenced treatment decisions and why the newer framework developed by The Lancet Diabetes & Endocrinology Commission on the Definition and Diagnosis of Clinical Obesity may offer a better path forward.

The traditional MHO/MUO framework generally classifies people with obesity based on the presence or absence of metabolic abnormalities. Under that approach, individuals with metabolically unhealthy obesity may be candidates for more intensive lifestyle interventions and pharmacotherapy, while those classified as having metabolically healthy obesity may initially receive structured lifestyle support, with more intensive treatment considered if their metabolic health worsens or other risk factors emerge.

The challenge is that the definition of MHO varies considerably across studies and is often not a stable condition. Individuals classified as having MHO may develop metabolic abnormalities over time, complicating treatment plans based on the assumption that their obesity is currently “healthy.” “Metabolically healthy obesity helped researchers recognize that obesity does not affect every person in exactly the same way,” Ravussin said. “But the classification is difficult to use as a foundation for long-term treatment because the definitions vary and metabolic health can change. A person who is considered metabolically healthy today may not be metabolically healthy tomorrow.”

The preclinical/clinical obesity framework proposed by The Lancet Commission takes a different approach. Rather than defining obesity primarily by the presence or absence of a specific cluster of metabolic risk factors, it considers whether excess adiposity is causing dysfunction in organs or tissues or limiting a person’s ability to perform daily activities.