IM14.1-5 | Obesity Foundations — Summary & Reflection

KEY TAKEAWAYS

Obesity in the Indian population is defined by Asian-Indian BMI cut-offs: overweight ≥23 kg/m², obese ≥25 kg/m² — lower than Western thresholds because South Asians accumulate metabolically dangerous visceral fat at lower BMI. Waist circumference cut-offs for central obesity: men ≥90 cm, women ≥80 cm.

Aetiology is multifactorial: polygenic predisposition + obesogenic environment (ultra-processed foods, sedentary occupations, sleep deficit, stress) + rare monogenic causes (LEPR, MC4R, POMC mutations) and secondary causes (hypothyroidism, Cushing syndrome, PCOS — always screen before labelling as primary obesity).

Metabolic syndrome (IDF 2005): central obesity (mandatory) + any 2 of TG ≥150, HDL <40/50, BP ≥130/85, FBG ≥100 mg/dL.

Natural history: adipose tissue dysfunction → insulin resistance → type 2 diabetes, cardiovascular disease, NAFLD, OSA, obesity hypoventilation, musculoskeletal complications, malignancy.

Management ladder: lifestyle modification (foundation) → pharmacotherapy (GLP-1 RAs, orlistat; BMI ≥27.5 with comorbidities or ≥32.5) → bariatric surgery (BMI ≥37.5 or ≥32.5 with major comorbidities).

Key clinical rule: always check serum TSH in new obesity presentations; use Asian-Indian cut-offs; measure waist circumference alongside BMI.

REFLECT

Rajan from our opening case had BMI 26, waist 94 cm, three metabolic syndrome components, and a family history of diabetes and early MI. By Western charts, he was 'slightly overweight.' By Asian-Indian standards and IDF metabolic syndrome criteria, he already had clinically significant disease requiring intervention. Consider: how would you explain to Rajan, who believes he is 'not that fat,' why his risk is real and why intervention should start now? How would you counsel him without triggering shame or defensiveness? The ability to translate scientific cut-offs into patient-centred communication — acknowledging the social and psychological dimensions of obesity without victim-blaming — is as important as knowing the numbers themselves.