Childhood Obesity in Vulnerable Populations: Epidemiology and Intervention Approaches

Children living with obesity, such as survivors of childhood brain tumors and children under 5 years of age in Nigeria, face a heightened risk of long-term adverse health consequences, including early-onset diabetes, cardiovascular diseases, and diminished overall quality of life. Despite an established understanding of obesity in the general pediatric population, significant knowledge gaps remain regarding pediatric groups particularly affected by biological and socioeconomic conditions. This thesis employed a comprehensive multi-method investigation to address knowledge gaps in our understanding of the epidemiology of, and intervention approaches to address, obesity in specific pediatric populations. These populations were intentionally selected to represent two distinct but complementary forms of vulnerability. Survivors of childhood brain tumors experience biologically driven vulnerability related to treatment effects, while children under five years of age in Nigeria experience structural vulnerability shaped by poverty, food insecurity, regional inequalities, and a rapidly changing environment during a critical stage of growth and development. Together, these contexts provide an opportunity to examine how biological and structural vulnerabilities shape childhood obesity in different settings. Methods This thesis adopted a “sandwich” thesis structure, integrating three original studies focusing on two pediatric populations. The first study is a scoping review of literature to map the evidence on intervention approaches for obesity management in survivors of childhood brain tumors (SCBT). This study sought to determine how obesity is defined, which participant characteristics are prioritized, and the types of interventions available for obesity management in this group. The second study is an updated systematic review and meta-analysis to provide the most robust estimate of the efficacy of pharmacotherapy interventions on anthropometric outcomes in SCBT. The third is a cross-sectional analysis of the 2018 Nigerian Demographic and Health Survey (NDHS) to estimate the prevalence, regional variation, and factors associated with obesity among children under five years of age. These studies were guided by the Socioecological Model, which provided the theoretical framework for analysis across these vulnerable populations. Together, these studies allow comparison of obesity across clinically vulnerable and structurally vulnerable child populations, providing a coherent framework to examine how different underlying drivers influence measurement, distribution and management of childhood obesity. Results In studies examining obesity in the SCBT population, obesity was inconsistently defined using body mass index (BMI) -related measures such as BMI z-scores and BMI percentiles, a narrow range of participants’ characteristics was collected, and three types of intervention approaches were administered 1) pharmacotherapy, 2) bariatric surgery, and 3) lifestyle interventions. There was limited efficacy of the pharmacotherapy interventions on anthropometric outcomes. Furthermore, in children under 5 years in Nigeria, obesity was prevalent, varied across regions and was associated with factors such as child age and household wealth, reflecting underlying social and economic inequalities. Conclusions These findings highlight that childhood obesity in vulnerable populations is driven by different underlying mechanisms depending on context. In clinically vulnerable groups such as survivors of childhood brain tumors, biological and treatment-related factors predominate, including hypothalamic injury and endocrine dysfunction, which also complicate measurement. In contrast, in children under five years of age in Nigeria, obesity is shaped more strongly by social and environmental conditions, including poverty, food systems, and regional inequalities. As a result, approaches to measuring, preventing and managing childhood obesity must be context-specific rather than relying on generic pediatric frameworks. This includes improving definitions and early treatment strategies in clinical populations, while in population settings, addressing broader structural determinants through policy and public health interventions.