Childhood prosocial behavior and body mass index: Longitudinal findings in the Millennium Cohort Study

Childhood obesity affects millions worldwide but is challenging to treat. Prosocial or helping behavior may help mitigate childhood obesity. We investigated whether prosocial behavior at ages 5-11 was associated with body mass index (BMI) and reduced obesity risk through age 17.

Data were from 8,894 participants in the Millennium Cohort Study. Parents reported children's prosocial behavior using the Strengths and Difficulties Questionnaire at ages 5, 7, and 11. BMI scores (kg/m2) were calculated from children's height and weight at ages 5, 7, 11, 14, and 17, which were then standardized by sex (M = 0, SD = 1) to examine BMI patterns in relation to the sample mean. Obesity risk was defined by established cut points from the International Obesity Task Force. Linear mixed models evaluated associations between age 5, 7, or 11 prosocial behavior and BMI Z scores (BMIz) through age 17, adjusted for relevant covariates, including baseline BMI. Associations with obesity risk were also examined at each follow-up assessment using logistic regression.

Obesity prevalence doubled from 5% to 10% between ages 5 and 17 years old. Prosocial behaviors at age 5 were not substantively associated with BMIz profiles or obesity risk. Similarly, associations between prosocial behavior at other developmental stages (ages 7 and 11, respectively) were largely unrelated to both subsequent BMIz patterns and obesity risk.

Associations between childhood prosocial behaviors and BMIz through age 17 were mostly null. No relationships were observed with obesity or with prosocial behaviors assessed later in childhood or adolescence. (PsycInfo Database Record (c) 2025 APA, all rights reserved).