Lancet Commission proposes replacing BMI-based eligibility with clinical obesity

A global expert commission convened by The Lancet Diabetes & Endocrinology has proposed scrapping body mass index as the deciding factor in who gets diagnosed with obesity, and replacing it with a two-category system based on whether excess body fat is actually damaging organs or limiting daily function. The report, "Definition and diagnostic criteria of clinical obesity," was published online Jan. 14, 2025, and appears in the journal's March 2025 issue, spanning pages 221–262 ^[1].

The commission draws a line between two states. "Clinical obesity" is defined as a chronic, systemic illness in which excess adiposity has produced documented dysfunction in organs or tissues, or has meaningfully limited a person's ability to carry out everyday activities. "Preclinical obesity" describes excess body fat with organ function still intact — a state of increased risk rather than current illness. Under the framework, BMI belongs in public health surveillance as a population-level screening tool, not as a stand-alone verdict on an individual's health.

The most consequential recommendation for American patients is the commission's argument that clinical obesity should stand on its own as a disease. In that view, a person with documented organ dysfunction from excess adiposity should not need a second condition — such as type 2 diabetes, high blood pressure, sleep apnea or high cholesterol — to justify treatment or insurance coverage. That directly challenges the model most US payers use, which typically requires a BMI of 30 or higher, or a BMI of 27 or higher plus at least one weight-related comorbidity, before a GLP-1 medication such as Wegovy (semaglutide) or Zepbound (tirzepatide) is approved.

The effort was large. The commission included 58 members and its conclusions were endorsed by 76 organizations. The author list published with the paper reflects that breadth: lead author Francesco Rubino of King's College London and King's College Hospital; David E. Cummings of the University of Washington and the VA Puget Sound Health Care System; Robert H. Eckel of the University of Colorado Anschutz Medical Campus; Fatima Cody Stanford of Massachusetts General Hospital and Harvard Medical School; W. Timothy Garvey of the University of Alabama at Birmingham; Robert F. Kushner of Northwestern University Feinberg School of Medicine; John P. Kirwan of Pennington Biomedical Research Center; and Francesco Branca of the World Health Organization's Department of Nutrition and Food Safety, among contributors from Australia, Brazil, Canada, Germany, Greece, India, Ireland, Japan, Singapore, Spain, Austria and Switzerland ^[1].

Industry ties are disclosed in the author affiliations. Commission member Rachel L. Batterham is listed with International Medical Affairs at Eli Lilly in Basingstoke, UK, in addition to University College London ^[1]. Eli Lilly makes tirzepatide, sold as Mounjaro and Zepbound.

Why it matters for patients

Coverage in the US often turns on a single number. Under current payer rules, two people with identical health problems can get different answers simply because one has a BMI of 29.4 and the other 30.1. The commission's framework would instead ask whether excess fat is measurably harming the heart, liver, joints, lungs, kidneys or mobility — which could pull some lower-BMI people into the "clinical obesity" category and move some higher-BMI people with normal organ function into "preclinical obesity."

A commission report is not a rule. It does not change Medicare, Medicaid or commercial plan policy, and it does not change FDA-approved labeling for semaglutide, tirzepatide or orforglipron (Foundayo). Whether any US payer adopts the language, and how long that would take, is not addressed in the material available here.

It is also worth noting what this story cannot tell you. The specific diagnostic criteria the commission proposes — the exact body-measurement thresholds, the list of qualifying signs of organ dysfunction, and the separate criteria for children and adolescents — are detailed in the full 42-page report and are not reproduced in the source text available for this article ^[1].

What happens next

The report was published online Jan. 14, 2025, and printed in volume 13, issue 3 of The Lancet Diabetes & Endocrinology ^[1]. Any change in US coverage rules would require action by individual insurers, employers, state Medicaid programs or the Centers for Medicare & Medicaid Services. No such timeline is described in the sources.