Background: This study aimed to further elucidate correlated weight changes in parent-child dyads enrolled in family-based treatment (FBT) by modeling the interdependence of weight changes during treatment. Methods: Parent-child dyads (n = 172) with overweight/obesity (child mean zBMI = 2.16 ± 0.39; parent mean BMI = 37.9 ± 9.4 kg/m2) completed 4 months of FBT and were randomized to one of three 8-month maintenance interventions (Social Facilitation Maintenance [SFM]-high dose, SFM-low dose or control). Weight/height was measured at 0, 4 and 12 months. Structural equation models simultaneously estimated the effect that an individual had on their own (actor effect) and on one another's (partner effect) weight-status across time using the actor-partner interdependence model. Results: Actor paths were significant over time for parent and child. Partner paths were significant for child zBMI predicting parent BMI at 4 and 12 months. Maintenance condition moderated actor/partner paths in the model. Conclusions: Child weight change may motivate parents to make environmental and behavioural changes that impact their own weight. Trial Registration: ClinicalTrials.gov Identifier: NCT00759746.
- actor-partner interdependence model
- family-based treatment
- long-term weight maintenance