Sex-specific patterns of thinness, underweight, and obesity among children and adults in seven South Asian countries: a secondary ecological analysis of NCD-RisC 2022 estimates

Abstract Background South Asia continues to experience pediatric thinness alongside rising obesity within the same populations, although these represent different individuals rather than simultaneous weight categories in one person. We performed a secondary ecological analysis of age-standardized 2022 NCD Risk Factor Collaboration (NCD-RisC) estimates for thinness and obesity in girls and boys aged 5–19 years and for underweight and obesity in women and men aged 20 years or older across seven South Asian countries. We derived the summed prevalence of thinness/underweight and obesity, the obesity share of this sum, adult-minus-pediatric obesity-share gradients, adult-to-pediatric obesity ratios, exploratory paired contrasts, and pediatric–adult rank concordance; a 100,000-draw simulation tested sensitivity to rounding of the published whole-percentage source values. Results Boys had higher thinness than girls in all seven countries (median 18% versus 14%; median paired difference 3 percentage points; Wilcoxon p = 0.0156), whereas pediatric obesity showed no consistent sex difference (median 5% in boys versus 7% in girls; p = 0.625). Adult obesity was higher in women than men in every country (median 15% versus 7%; median difference 6 percentage points; p = 0.0156). Country rankings for pediatric and adult obesity were concordant (Spearman rho = 0.782 for female strata and rho = 0.901 for male strata). Pakistan combined substantial pediatric thinness with the comparator panel's highest obesity prevalence in boys (10%), women (27%), and men (20%), and had the largest adult-minus-pediatric obesity-share gradient (46.1 points in female strata and 39.6 points in male strata). India retained the highest pediatric thinness (20% in girls and 22% in boys). The rounding-sensitivity analysis preserved the principal directional findings. Conclusions The contemporary South Asian nutrition transition is sex-divergent and incomplete: pediatric thinness and obesity are both present in national populations, alongside substantially greater adult obesity, especially among women. Pakistan shows a particularly concerning combination of these population-level patterns in this seven-country comparison. Pediatric endocrine and internal-medicine strategies should combine early obesity and cardiometabolic prevention with continued identification and treatment of thinness, while strengthening transition-focused care from adolescence into adulthood.