BackgroundChildhood obesity prevention interventions routinely focus on changing maternal parenting practices. Failure to assess how fathers’ weight-related (ie, diet and physical activity) parenting practices contribute to children’s energy balance behaviors limits the understanding of their paternal role within the family. Examining the independent and interacting effects of fathers’ and mothers’ weight-related parenting practices on children’s diet and physical activity addresses this important research gap.ObjectiveThis study used ecological momentary assessment (EMA) to investigate the within-subject and between-subject independent and interactive effects of maternal and paternal encouragement to eat and preparation of fruits and vegetables (F/V) and encouragement of and taking their child to be physically active on their child’s self-reported F/V intake and physical activity engagement.MethodsParticipants included mother-father-child triads (n=22 triads, n=205-213 prompts/occasions) in the Mothers and Their Children’s Health Study and the University of Southern California Fathers Study. Simultaneously, mothers and fathers (agesmean 44.2 years, SD 5.6, and 45.2 years, SD 8.1, respectively), and their children (agemean 12.0 years, SD 0.7) completed up to 8 randomly prompted EMA surveys per day on separate smartphones for 7 days. At each prompt, mothers and fathers each reported whether they did the following in the past 2 hours: (1) encouraged their child to eat F/V, (2) prepared F/V for their child, (3) encouraged their child to be physically active, or (4) took their child to be physically active. Children self-reported whether they consumed F/V or were physically active in the past 2 hours.ResultsResults from Bayesian multilevel logistic models (all in log-odd units) indicated that at the within-subject level, greater maternal encouragement (β=2.28, 95% CI 0.08 to 5.68) of eating F/V was associated with greater child report of eating F/V, but paternal encouragement (β=1.50, 95% CI –0.83 to 4.52) showed no effects above and beyond maternal encouragement. Additionally, greater than usual paternal encouragement (β=2.28, 95% CI 0.08 to 5.54) and maternal encouragement (β=2.94, 95% CI 0.36 to 6.69) of physical activity had significant independent effects and were associated with greater child report of physical activity. No other within-subject or between-subject associations nor interactive effects were significant.ConclusionsFindings from this study suggest that fathers play a role in supporting their children’s physical activity but not their intake of F/V. Future EMA studies should recruit larger samples to evaluate the independent and interacting roles of mothers’ and fathers’ weight-related parenting practices on child’s obesogenic behaviors.