From Childhood to Adolescence: Long-Term Trends in Severe Obesity in German Youth (2002-2023).

Introduction: Research on severe obesity (SO) is scarce and often contradictory. As higher weight status persists into adulthood, we aimed to analyze long-term trends in the prevalence of SO in children and adolescents in Germany using a large real-world data set. Furthermore, we analyzed subgroup differences and assessed how the COVID-19 pandemic affected weight status.

Methods: We analyzed data from the CrescNet auxological network, including 1,495,401 clinical visits by 4- to 16-year-old children (2002-2023). Weight trends were examined with a focus on SO using logistic regression, stratified by sex and age. Effects are reported as odds ratio per 5 years (OR5) pre-pandemic and as OR for consecutive years during the pandemic. Quantile regression assessed trends of the 50th, 90th, 97th, and 99th percentiles of excess weight.

Results: Pre-pandemic, SO remained stable or declined in children under 12 until 2010: OR5: 0.8-1, p < 0.001) but rose significantly afterward (OR5: 1.1-1.2, p < 0.001). Children between 12 and 16 years of age showed a continuous increase, especially boys (boys12-16: OR5: 1.3, girls12-16: OR5: 1.1, p < 0.001). During the pandemic, SO peaked in 2021 across all groups (OR21 vs. 19: 1.3-1.7, p < 0.001). By 2023, younger children had returned to pre-pandemic levels, while older children, particularly 8- to 16-year-old girls, remained at higher weights (OR23 vs. 19: 1.2-1.5, p < 0.001-0.002). Weight gain was most prominent in SO groups but could also be seen in pre-pandemic and pandemic overweight and obesity subgroups, generally decreasing toward the end of the pandemic.

Conclusion: SO has increased over the last 2 decades, with the COVID-19 pandemic accelerating this trend, particularly in adolescents. While younger children recovered by 2023, excess weight in older children, especially girls, continues to escalate.