Does deciding not to participate in a lifestyle intervention for children with obesity affect the long-term weight change?

Objective: The objective of this study was to investigate whether long-term weight change in children with obesity is affected after deciding not to participate in a lifestyle intervention.

Methods: This observational study included 713 children (aged 5-8 years) with obesity living in Aarhus, Denmark, of whom 157 decided not to participate in a community-based lifestyle intervention between 2010 and 2020, and 556 were never invited to participate (i.e., no-intervention group). Height and weight measurements were combined with socioeconomic information from national registers. A mixed-effects model with splines was used to model changes in BMI z score and stratification to investigate effect modifications.

Results: We observed a median follow-up of 3.6 years (quartile [Q]₁;Q₃: 0.4;5.1) for the decided-not-to-participate group. No difference was observed in annual change in BMI z score between the decided-not-to-participate and no-intervention groups (0.00 per year, 95% CI: -0.03 to 0.03; p = 0.90). No effect modifications were observed between the two groups concerning highest completed household education (p = 0.59), household income (p = 0.72), or immigration status (p = 0.17).

Conclusions: Children deciding not to participate in an intervention did not increase their weight compared with children who were never invited, indicating that treatment could be briefly postponed until families are able to participate. Additionally, socioeconomic status or immigration background did not modify the weight change.