Reference: Lancet Diabetes Endocrinol. 2025 Jan 14 early online
Practice Point: We may soon be looking at a new framework for diagnosing obesity that requires evidence of both clinical impairment of body functioning as well as excess adiposity, even at a “normal” BMI.
EBM Pearl: The Delphi technique is a method used in a variety of settings (economics, health care, science) to systematically arrive at a consensus among experts in the field being studied. It uses anonymous, structured, and iterative responses to questions to find areas of agreement.
Anti-obesity medications are all over the news these days and increasingly considered to be a long-term treatment option for the chronic disease of obesity. For many providers, fielding the constant flurry of messages about prior auths, formulary restrictions, and pharmacy shortages, the smell of overuse is becoming stronger by the week. But if obesity is an epidemic, how could addressing it by any means necessary be considered overuse? Perhaps the problem lies in how we currently define obesity, as simply having a BMI >/= 30 kg/m2. What if the conceptual framework upon which we (and big pharma) have built an anti-obesity empire is faulty? Recommendations recently published in the Lancet by a newly created Global Commission on Clinical Obesity propose a system that utilizes both anthropomorphic and clinical data to separate people with elevated BMI or body weight into clinical and preclinical subgroups based on new diagnostic criteria that include both objective evidence of excess adiposity (that doesn’t necessarily require an elevated BMI) AND evidence of clinical impairment of body functioning.
The Commission was composed of 58 experts, some living with obesity, who represented different medical specialties and countries. The panel was systematically surveyed using a modified Delphi technique, with unanimous consensus reached on 49 of 82 statements and near-unanimous consensus (> 90%) reached on an additional 33 of 82 statements. These consensus statements resulted in the creation of specific diagnostic criteria for the diagnosis of clinical obesity in adults as well as in children and adolescents.
The Commission acknowledges that obesity is a heterogeneous condition with a spectrum of phenotypes. For instance, some people with obesity can have poor health and medical problems due to obesity alone, and some people with elevated BMIs can have normal function and health for as long as they live. The framework proposed by the Commission distinguishes obesity, clinical obesity, and preclinical obesity as follows:
- Obesity: excess adiposity alone, with or without resulting functional impairment
- Clinical obesity: excess adiposity resulting in chronic systemic illness with tissue or organ dysfunction or limitations in activities of daily living
- Preclinical obesity: excess adiposity with preserved function but generally increased risk of developing clinical obesity and other comorbidities
In a nutshell, this change deemphasizes BMI and other surrogate markers alone and instead zooms in on evidence of dysfunction related to excess adiposity, allowing prevention and treatment to be focused on preclinical and clinical obesity, not just obesity alone.
We’ve known for a long time that BMI is an imperfect measurement—its use leads to underdiagnosis in people with sarcopenic obesity (low muscle mass but high body adiposity) and overdiagnosis in people with muscular bodies (bodybuilders). Some purists in the past have proposed using body composition measurements to diagnose obesity, but there is no universally recommended low-cost method for this. One of the advantages of this newly proposed method is that it requires assessment of functional impairment related to excess adiposity using specific, consistent clinical criteria. If we use BMI as an initial screening test (for nonpregnant individuals), three groups of people with elevated BMIs might fall out: muscular athletes (low adiposity and no disease), those with high adiposity and no apparent disease (preclinical obesity), and those with high adiposity and disease (clinical obesity). Diagnosis based on this consensus recommendation is both systematic and nuanced at the same time.
The Commission’s proposal, if adopted, might radically change both how we think of populations and individuals when it comes to obesity. It theoretically reduces both under- and overdiagnosis of obesity, allows us to better target preventive and therapeutic measures, and by extension potentially improves population-based outcomes. This new model of defining obesity could also serve as a starting place to reduce the stigma experienced by many around obesity by shifting the focus to clinical impairment and away from weight itself. Oh, and it might eventually lead to a more judicious and appropriate use of GLP-1s. So, stay tuned to see if the major obesity-related organizations embrace these definitions—because when we define obesity with a holistic and nuanced approach, we can finally stop letting it define us.
DynaMed EBM Focus Editorial Team
This EBM Focus was written by Katharine DeGeorge, MD, MS, Senior Deputy Editor at DynaMed and Associate Professor of Family Medicine at the University of Virginia. Edited by Alan Ehrlich, MD, FAAFP, Executive Editor at DynaMed and Associate Professor in Family Medicine at the University of Massachusetts Medical School; Dan Randall, MD, MPH, FACP, Senior Deputy Editor at DynaMed; McKenzie Ferguson, PharmD, BCPS, Senior Clinical Writer at DynaMed; Rich Lamkin, MPH, MPAS, PA-C, Clinical Writer at DynaMed; Matthew Lavoie, BA, Senior Medical Copyeditor at DynaMed; Hannah Ekeh, MA, Senior Associate Editor II at DynaMed; and Jennifer Wallace, BA, Senior Associate Editor at DynaMed.