Supplementary Material for: Autism spectrum disorder and obesity in children: A systematic review and meta-analysis

Introduction: Children and adolescents with autism spectrum disorder (ASD) appear to be at greater risk of excess weight gain. The aim of this systematic review and meta-analysis was to examine whether children with ASD have a greater prevalence of obesity and whether the prevalence of ASD is higher in children with obesity. Methods: We conducted a systematic search on PubMed, Scopus and PsychINFO until May 21, 2021. We used the meta package in the R in order to calculate the pooled prevalence and relative risk of obesity in children with ASD. Results: We found 20 eligible studies investigating the prevalence of obesity in children with ASD, with the prevalence ranging from 7.9 to 31.8% and from 1.4 to 23.6% among controls. All but three studies originated from the US. The proportion of children with obesity in ASD populations was 17% (95 % CI: 13-22). The relative risk of obesity in children with ASD compared with control children was 1.58 (95% CI: 1.34-1.86). There were no controlled studies reporting on the prevalence of ASD in children with obesity. Conclusion: Children and adolescents with ASD have a higher prevalence of obesity than healthy controls. There is a need for further prevalence studies of obesity in children with ASD, especially outside the United States, since the few European studies carried out have failed to show a significant difference between obesity prevalence in children with and without ASD. There is no knowledge at all regarding the prevalence of ASD among children with obesity.