Longitudinal assessment of body composition and pulmonary function

Introduction: Childhood obesity continues to rise at an alarming rate in the United States with currently over fifteen million children and adolescents between 2-19 being classified as with obesity. The excess fat on the chest wall can exert an unfavorable burden on the respiratory system, thereby altering pulmonary function. Yet, how these obesity-related effects might change longitudinally with age are unknown in children with obesity. Therefore, the purpose of this study was to determine how obesity during growth affects pulmonary function. Methods: Twenty-three children were evaluated at baseline (8-12 years, Tanner stage ≤3) and after 7.2 ± 0.3 years, including 6 classified as children without obesity (CWOO, BMI 15th-85th percentile, 4 boys / 2 girls) and 17 classified as children with obesity (CWO, BMI ≥95th percentile,12 boys / 5 girls). At baseline and follow up, DEXA and pulmonary function testing were obtained. The groups were defined based on BMI at baseline and all children were considered within the same group for follow-up testing. Results: Participants were 10.1 ± 0.9 years old at baseline and 17.3 ± 1.3 years old at follow-up. At baseline, body mass index (BMI) was 18 ± 1kg/m 2 (79th percentile for age) in CWOO vs. 27 ± 4 kg/m 2 (98th percentile for age) in CWO (P< 0.001). At follow up, BMI remained greater in CWO (CWOO 24 ± 2 kg/m 2 (66th percentile for age) vs. CWO 34 ± 9 kg/m 2 (93rd percentile for age, P = 0.003). However, fat mass increased more in children with obesity throughout the study (CWOO: 1.38 ± 0.54kg/year vs. CWO: 3.61 ± 1.11kg/year, P< 0.001). Trunk fat was higher at baseline in CWO (CWOO: 3 ± 1kg vs. CWO: 11 ± 10kg, P=0.0056) and this difference persisted at follow up (CWOO: 10 ± 10kg vs. CWO: 20 ± 10kg, P=0.0005). At baseline and follow-up both groups showed no difference in forced vital capacity (CWOO: 117 ± 18 to 114 ± 13 %predicted vs. CWO: 109 ± 9 to 114 ± 13 %predicted, P=0.527) and forced expiratory volume in 1 second (CWOO: 109 ± 13 to 112 ± 21 %predicted vs. CWO: 104 ± 8 to 109 ± 12 %predicted, P=0.060). Similarly, total lung capacity (TLC) was not different at baseline and follow-up (CWOO: 101 ± 9 to 131 ± 20 %predicted vs. CWO: 101 ± 11 vs. 128 ± 13 %predicted, P=0.7916). However, CWO had a reduced functional residual capacity (%TLC) at baseline (CWOO: 51 ± 4% vs. CWO: 44 ± 6%, P=0.0006) and this difference persisted at follow up (CWOO: 39 ± 9% vs. CWO: 49 ± 4%, P=0.0006). Conclusion: Our preliminary data show that fat mass increases at a faster rate in children with obesity as compared with children without obesity suggesting that obesity in childhood may accelerate during growth into adolescence. Also, the only significant effect of obesity on pulmonary function was a reduction in functional residual capacity, which persisted from early childhood through to adolescence. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.