Childhood obesity has significant health consequences, including increased risk of developing chronic diseases such as type 2 diabetes and cardiovascular complications . The psychological and behavioural impacts are also well documented, and include bullying, social isolation, poor self-esteem, and disordered eating [2, 3]. Given the likelihood of excessive weight persisting from childhood into adulthood , interventions targeting the prevention of excessive weight gain in childhood have been recommended to avert the future health burden of obesity .
An important determinant of child weight status is the consumption of ‘non-core foods’, that is, foods that are high in fat, salt or sugar . The positive association between excessive consumption of non-core foods and obesity in children and adults is well established . Similarly, interventions targeting reductions in the intake of non-core foods have been found to be effective in preventing excessive weight gain in children . Accordingly, recommendations for the prevention of overweight and obesity encourage diets consistent with healthy eating guidelines which state that children only consume non-core foods occasionally, and in small amounts .
Early childhood represents an ideal opportunity for dietary intervention as preschool-age children are imitative of the dietary behaviours and eating patterns of their parents and authority figures, and as dietary attitudes and behaviours established during this period often persist into adulthood . Furthermore, there appears to be capacity to influence young children’s food preferences through the social-affective context in which foods are offered . A number of parent and home food environment factors are thought to be particularly influential to the development of a child’s diet . The availability and accessibility of non-core foods are necessary prerequisites for their consumption and are unsurprisingly positively associated with child non-core food consumption . However, restricting access can increase child preference for and intake of non-core food in the absence of parental monitoring . Parental pressure for children to eat, and the use of strategies that focus children’s attention on rewards or punishments, consuming all on their plate, or television viewing, is thought to hinder the development of child self regulation of their eating, particularly in response to energy dense foods [12–15]. The use of non-core food rewards can also adversely impact on child diet through reinforcing child preference and liking for the food reward . However, role modelling healthy food habits by eating meals together as a family at the dinner table , and high parental self-efficacy regarding child feeding has also been suggested to be positively associated with healthier child diet [17, 18].
Given the relationships between parent and home environment characteristics, interventions targeting such characteristics have been recommended to improve child diet and reduce the risk of excessive weight gain [4, 19]. Currently, however, few trials have been conducted examining the effectiveness of interventions incorporating parent and home environment strategies. Three recent systematic reviews found a total of only eight nutrition-based obesity prevention studies targeting parents of preschool-aged children [16, 18, 20]. The studies varied considerably in terms of intervention setting, intensity, delivery modalities and the parent and home food environment characteristics targeted, limiting the capacity for researchers and practitioners to identify the components of effective initiatives.
Mediation analysis allows researchers to identify mechanisms by which one variable influences another , can assist in understanding the causal pathways by which interventions operate , and has been recommended as a means of improving the design and effectiveness of future obesity prevention interventions . As such, investigating the mediators of effective interventions that target parent and home food environment characteristics may allow an assessment of how such interventions are effective, and how they may be improved. Despite recommendations that mediation analysis be routinely used in intervention studies , its application in childhood obesity research is in its infancy. To our knowledge there have been no published mediation studies of interventions targeting dietary outcomes of pre-school aged children. A recent systematic review of interventions that examined mediators of dietary behaviour change in 5-18 year olds identified just seven studies . The review found no convincing evidence for any of the investigated mediating variables, but highlighted the limitations of the included studies such as low power, insensitive measures, and ineffective intervention strategies.
‘Healthy Habits’ is a randomised controlled trial of a telephone-based parent intervention targeting parent and home food environment characteristics as a means of improving child diet . The aim of the present study was to assess the effectiveness of the intervention in reducing child consumption of non-core foods, a secondary outcome investigated in the trial. We also sought to conduct an exploratory analysis of the causal mechanisms of this dietary change through mediation analysis.