Condition
Obesity
Obesity is recognized by major medical societies as a chronic, relapsing, multifactorial disease characterized by excess adipose tissue with adverse health consequences.
How obesity is defined
Obesity is most commonly screened with body mass index (BMI ≥ 30 kg/m²). BMI is useful at the population level but limited at the individual level because it does not distinguish lean mass from fat mass or describe where fat is stored. Clinicians often incorporate waist circumference, body composition, and complication staging (e.g., AACE's Adiposity-Based Chronic Disease framework).1
Why it develops
Obesity results from interactions among genetic susceptibility, hormonal regulation, diet quality and quantity, physical activity, sleep, stress, the gut microbiome, certain medications, and the broader food environment. It is not a failure of willpower, and addressing it as such is inconsistent with current evidence.
Health consequences
Obesity is associated with elevated risk of type 2 diabetes, hypertension, dyslipidemia, MASLD/MASH, obstructive sleep apnea, certain cancers, osteoarthritis, and cardiovascular disease. Risk is not deterministic — many people with obesity remain free of complications for years, while others develop complications at lower BMIs.
Evidence-based care
Major options include structured lifestyle interventions (nutrition, physical activity, sleep, behavioral support), FDA-approved pharmacotherapy (including GLP-1 and GIP/GLP-1 receptor agonists), endoscopic therapies (e.g., endoscopic sleeve gastroplasty), and bariatric/metabolic surgery (sleeve gastrectomy, Roux-en-Y gastric bypass, among others). Selection should be individualized with a qualified clinician. See Evidence-Based Treatment Pathways.