When obesity becomes a disease
An international commission proposes an overhaul of obesity diagnosis, no longer limited to body mass index, to define at which stage obesity becomes a disease.
Press release, Paris, January 15, 2025
A commission of 58 experts [1] from different countries and medical specialties, as well as obesity patients, warns of the alarming figures for obesity worldwide. The commission’s aim was to reach a consensus based on up-to-date evidence. It defined “clinical” obesity as a chronic, systemic disease linked to excess adiposity in numerous organs and tissues whose functions are impaired, with or without abnormal distribution or function of the adipose tissue itself. Its causes are multifactorial and incompletely understood. Damage to the affected organs is the source of serious complications: metabolic (diabetes), cardiovascular, cerebrovascular, renal, cancerous, and mortality proportional to body fat. “Preclinical” obesity refers to excessive adiposity without clinical damage, but with the risk of progressing to clinical obesity and its complications.
The distinction between preclinical and clinical obesity is necessary, both in terms of clinical management and with regard to health policy. There are a number of pitfalls to this approach, starting with the body mass index (BMI) used to define obesity, which is misused and penalizes care approaches. BMI is useful for epidemiological risk assessment and screening. Above 40 kg/m2, it may be sufficient to reflect the existence of obesity. Between 25 and 40 kg/m2, it is not sufficient. Diagnosis of obesity requires direct measurement of body fat, where possible, or quantification of anthropometric parameters (waist circumference, waist-to-hip ratio, waist-to-height ratio) using validated methods and thresholds adapted to age, gender and ethnic origin. To qualify as clinical obesity, one or the other of two main criteria must be present: functional impairment of an organ or tissue due to obesity (clinical signs, functions of one or more tissues or organs), or significant reduction in age-adjusted daily activities: mobility, daily activities (toileting, dressing, continence, eating).
Patients with clinical obesity should receive evidence-based treatment for obesity and associated clinical conditions, to prevent progression to irreversible damage. Patients identified as preclinical obese should benefit from treatment combining recommendations, in particular physical activity and diet, medical follow-up and, where appropriate, therapeutic care to reduce the risk of progression to clinical obesity and associated diseases, depending on individual risk.
Policy-makers and health authorities must ensure that people with clinical or preclinical obesity have equitable access to diagnostic assessment, follow-up and treatment tailored to their individual risk level by appropriately trained professionals. Public health strategies aimed at reducing the incidence and prevalence of obesity at population level must be based on evidence, rather than on unvalidated hypotheses, and by associating obesity with individual responsibility. Weight-related prejudice and the resulting stigmatization are further obstacles to efforts to prevent and treat obesity effectively.
[1] Definition and diagnostic criteria of clinical obesity. Lancet Diabetes Endocrinology, 2025 Jan 9: S2213-8587(24)00316-4. Doi : 10.1016/S2213-8587(24)00316-4. PMID: 39824205.published online 14 Jan 2025.
Martine Laville (Lyon, author of the report “Better prevention and management of obesity in France”), Karine Clément (Paris, President of the Association Française d’Étude et de Recherche sur l’Obésité) and François Pattou (Lille, President of the Société Française et Francophone de Chirurgie de l’Obésité et des Maladies Métaboliques) were the French members of this Commission.
The proposed recommendations met with a broad consensus among the members of the Commission (level of agreement between 90 and 100%), and were endorsed by 75 organizations worldwide, including learned societies and patient organizations.
jan 2025.
CONTACT PRESSE : Virginie Gustin +33 (0)6 62 52 43 42 virginie.gustin@academie-medecine.fr ACA-DÉMIE NATIONALE DE MÉDECINE, 16 rue Bonaparte – 75272 Paris cedex 06 Site : www.academie-me-decine.fr / Twitter : @Acadmed
