Evaluating the role of anthropometric variables in identifying obesity among Ao Naga adults in Northeast India

Anthropometric variables vary in diagnostic utility across populations and sexes, and indigenous Indian communities remain underrepresented in such evaluations. The aim of the study was to assess the sex-specific performance of waist-hip ratio (WHR), waist-to-height ratio (WtHR), mid-upper arm circumference (MUAC), and body adiposity index (BAI) for identifying obesity among Ao Naga adults of Northeast India. A cross-sectional investigation was conducted among 103 adults (53 men, 50 women) in Kohima, Nagaland. Obesity was defined by BMI (WHO-recommended Asian cut-off, ≥ 25 kg/m²) and, as an independent reference standard, the body fat percentage (BF%) measured via bioelectrical impedance analysis (≥ 25% for men; ≥ 35% for women) was used. Sex-specific logistic regression and receiver operating characteristic (ROC) analyses were performed against both reference standards, with the area under the curve (AUC), optimal cut points, sensitivity, and specificity reported for each. Women showed higher BAI and BF%. For BMI-defined obesity, WtHR and BAI showed stronger discrimination than WHR and MUAC in men (AUC 0.850 and 0.805 vs. 0.598 and 0.654) and excellent accuracy in women (AUC 0.977 and 0.907 vs. 0.694 and 0.610). Optimal WtHR cut points were 0.538 in men and 0.564 in women. When compared to directly measured body fat, the ranking remained unchanged, with WtHR and BAI again outperforming WHR and MUAC; WHR performed at the chance level in women. The study found that WtHR and BAI outperformed WHR in identifying both BMI-defined and body fat-defined obesity among Ao Naga adults, particularly in women. The findings highlight the importance of developing population-specific standards that are sensitive to sex and population.