Obesity and asthma are major global health concerns, particularly in industrialized nations. Obesity has been shown to have detrimental effects on the respiratory system and lung function owing to metabolic issues and immunological consequences. Research has indicated that obese patients with asthma (atopic or T2-high and non-atopic or T2-low) have diminished lung function in terms of functional residual capacity (FRC), residual volume (RV), expiratory reserve volume (ERV), the FEV1/FVC ratio, and FEF 25–75% due to mechanical fat loading on the diaphragm and central adiposity when compared to non-obese asthmatic patients. Therefore, it is plausible that changes in lung function are the result of a combination of mechanical (fat loading on the diaphragm, central adiposity, bronchial hyper-reactivity, and an increase in cholinergic tone), environmental (diet and exercise), and inflammatory factors (local and systemic), which can lead to the obesity-related asthma phenotype characterized by severe asthma symptoms, poor response to corticosteroid treatment, loss of lung function, and poor quality of life from an early age.

Background/Objectives: Pubertal maturation encompasses hormonal, somatic, and metabolic alterations that may influence pulmonary function in children with asthma. We evaluated the correlates of pulmonary function in pediatric asthma using sex-stratified analyses of pubertal stage, BMI z-score, asthma control (ACQ-6), and HDL cholesterol levels on FEV1, FVC, and the FEV1/FVC ratio (% predicted, NHANES III). Methods: A cross-sectional study was conducted with 118 children and adolescents with asthma (74 males and 44 females). The Tanner stages were categorized as pre-/early (I–II), mid (III), and late (IV). No participant had reached Tanner stage V at recruitment, and the reference category was composed predominantly of Tanner II participants; therefore, the pubertal contrast reflected early- versus mid-/late-pubertal physiology rather than a strictly prepubertal-versus-pubertal comparison. We performed hierarchical linear regression with bias-corrected and accelerated bootstrap inference (5000 replicates) for each sex and for all participants combined, complemented by a formal sex × predictor interaction test. Results: Mid- and late puberty were independently associated with reduced FEV1% and FVC% (β −0.25 to −0.31), without affecting the FEV1/FVC ratio. Sex-stratified analyses were exploratory and identified apparently divergent predictor sets by sex: in males, the pubertal stage was significant in FEV1% and FVC% (β −0.30 to −0.42), whereas the BMI z-score diminished the FEV1/FVC ratio (β = −0.274). In females, FEV1% was associated with HDL-c (β = 0.463), BMI z-score (β = 0.429), and ACQ-6 score (β = −0.306); the female FEV1/FVC% model showed a substantial apparent effect (Cohen’s f² = 0.508), with ACQ-6 score and HDL-c as primary associated variables. The formal sex × predictor interaction test in the combined sample, however, did not reach statistical significance (ΔR² = 0.037; p = 0.178), indicating that the sex-differential patterns observed in the stratified models were not confirmed as effect modifications. Conclusions: Sex-stratified exploratory analyses in this pediatric asthma cohort identified apparently divergent patterns of associations in males and females; however, the formal interaction test was not statistically significant, indicating that these stratified differences were not confirmed and require validation in adequately powered prospective cohorts. These findings identify HDL-c, body composition, and symptom control as candidate correlates of pulmonary function, with potential sex-related differences warranting further investigation.