Obesity Pharmacotherapy

Introduction & indications

• Obesity — a chronic, relapsing, progressive disease of excess/dysfunctional adipose tissue that impairs health. Pharmacotherapy is an adjunct to — never a replacement for — lifestyle therapy (medical nutrition therapy, physical activity, behavioural modification), because every agent carries adverse effects and weight is regained on discontinuation; drug therapy is conceived as long-term/chronic, mirroring antihypertensive treatment.
• Indications & BMI thresholds — chronic anti-obesity drugs are indicated at BMI ≥30 kg/m² (obesity), OR BMI ≥27 kg/m² (overweight) with ≥1 weight-related comorbidity (hypertension, type 2 diabetes, dyslipidaemia, obstructive sleep apnoea, cardiovascular disease). Orlistat is additionally approved from age ≥12 y.
• Asian-Indian thresholds — obesity in Asian Indians manifests at lower BMI with greater central/visceral adiposity, so action points are lower — treat at BMI ≥27.5 with comorbidity, with emphasis on waist circumference (≥90 cm men, ≥80 cm women) and waist-to-height ratio. The ESI 2025 guideline uses a two-stage adiposity-based definition (Stage 1 = adiposity without organ dysfunction; Stage 2 = adiposity with mechanical/metabolic complications), addressing the South-Asian "thin-fat" phenotype.