Metabolically Obese Non-Obese Phenotype Accounts for the Largest Share of Obesity Subtypes in India: ICMR-INDIAB Study

The study was published in the Indian Journal of Medical Research in May 2025.

While obesity is traditionally associated with cardiometabolic dysfunction, the presence of metabolically unhealthy individuals with normal body weight and metabolically healthy individuals with obesity points to a critical gap in BMI-centric risk assessment. To address this, Dr. M. Deepa from the Department of Epidemiology at the Madras Diabetes Research Foundation (MDRF), Chennai, and colleagues evaluated the national prevalence of obesity subtypes and their associations with type 2 diabetes (T2D), coronary artery disease (CAD), and chronic kidney disease (CKD).

The investigators conducted a large-scale, nationally representative cross-sectional survey of 113,043 adults; 19,370 participants underwent comprehensive metabolic screening involving lipids, glycated hemoglobin (HbA1c), serum creatinine, and 12-lead electrocardiograms (ECG). Using Body Mass Index (BMI) and clinical markers—including Waist Circumference (WC), Blood Pressure (BP), and High-Density Lipoprotein (HDL) cholesterol—investigators classified individuals into Metabolically Healthy Non-Obese (MHNO), Metabolically Healthy Obese (MHO), Metabolically Obese Non-Obese (MONO), and Metabolically Obese Obese (MOO) phenotypes.

Key Clinical Findings of the Study:

• Dominance of the MONO Phenotype: The MONO phenotype is the most prevalent obesity subtype in India, affecting 43.3 percent of adults and occurring more frequently in rural regions and among males.

• Elevated Risks in MOO Phenotypes: Individuals with MOO status carry the highest risk for T2D (Odds Ratio [OR]=12.89) and CAD (OR=1.92), with females showing a particularly high risk for diabetes.

• Renal Implications for MONO Patients: Patients in the MONO category face the highest risk of CKD (OR=1.81), with females exhibiting a markedly higher vulnerability to renal complications compared to other phenotypes.

• Prevalent Metabolic Risk Factors: Low HDL cholesterol and elevated BP are the leading metabolic abnormalities, impacting 79.2 percent and 69.5 percent of the population, respectively.

• Age-Related Metabolic Deterioration: Clinical data indicate that as age increases, the prevalence of healthy phenotypes like MHNO and MHO decreases, whereas the high-risk MONO subtype rises significantly.

The results suggest that with 43.3 percent of the adult population classified as MONO and facing an elevated risk for CKD, diagnostic strategies must shift from a reliance on BMI toward more holistic clinical assessments to ensure early intervention.

The authors conclude that healthcare providers transition from weight-centric screening to holistic metabolic evaluations, as a normal BMI often masks significant risks for non-communicable diseases (NCDs). Routine practice should integrate accessible markers like WC and BP to identify and manage high-risk patients who appear lean but remain metabolically compromised.

Reference

Deepa M, Pradeepa R, Venkatesan U, et al. High prevalence of metabolic obesity in India: The ICMR-INDIAB national study (ICMR-INDIAB-23). Indian J Med Res 2025; 161: 461-72.