Towards obesity resistance in children: Assessing the predictors of healthy behaviours within the family environment.

Author: Gilly Hendrie

Hendrie, Gilly, 2010 Towards obesity resistance in children: Assessing the predictors of healthy behaviours within the family environment., Flinders University, School of Medicine

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Understanding the determinants of behaviour in children is crucial to curb the current population obesity trends. Children's behaviour develops within the home, making it a target for obesity prevention efforts. Previous research has identified a network of parental factors that are thought to influence children's health-related behaviour including weight, health-related knowledge and behaviour, parenting styles and practices, to name but a few. This complexity makes it important to use theory or models to guide research and to determine the relative importance of factors within the home environment to improve the effectiveness of future obesity prevention interventions. Embedded in psychological theory and nutrition education principles is the concept that knowledge is required for behaviour change. This thesis provides much-needed support for the theoretical foundation that nutrition knowledge is a determinant of dietary intake behaviour. The measurement of knowledge and the collection and interpretation of intake data are often cited as limitations to research & issues this thesis aimed to address. Modifications were made to an existing measure of nutrition knowledge, and a validation exercise conducted within a heterogeneous Australian community setting provided a valid and reliable assessment tool to measure knowledge. Single nutrient or food group analysis omits the synergistic nature of whole diet. A key component of this thesis was the modification of the United States Department of Agriculture's Healthy Eating Index to be consistent with Australian dietary guidelines and its application to the interpretation of dietary intake. An exploratory study, using the validated knowledge tool and modified diet quality index, revealed that some of the basic nutrition guidelines, such as eat more vegetables and less fatty foods, are reaching the community, but detailed knowledge of the nutrient content of foods, diet-disease relationships and making healthier food choices is poor. Indeed, knowledge was shown to be a significant independent predictor of dietary intake and diet quality. Knowledge was shown to be a stronger predictor of overall diet quality than of any single nutrient or food group. The second aim of this thesis was to disentangle the relative importance of family environmental factors in the context of obesity resistance in children. A 12-month longitudinal study involved 154 South Australian families with primary school-aged children, and used structural equation modelling and previous research to present a model of obesity resistance. The proposed model showed an acceptable fit (NFI=0.458; CFI=0.741; RMSEA=0.045). Parents' BMI (β=0.34*) and knowledge (β=-0.21*) had the strongest direct associations with children's obesity risk. Parents' intake and expenditure behaviours were indirectly associated with children's behaviours through the creation of the home environment. The physical activity environment was associated with children's sedentary (β=-0.44*) and activity habits (β=0.29*). The food environment was associated with fruit and vegetable intake (β=0.47*). General parenting styles (β=0.63*) and child feeding practices (β=-0.74*) were associated with the family environment. Parents' knowledge also had a direct influence on their parenting practices & parenting style (β=0.25*) and feeding practices (β=-0.50*). The proposed model provided a comprehensive insight into the potential avenues for intervention within the complex network of factors that make up the family home environment.

Keywords: obesity,obesity prevention,children,family environment
Subject: Public Health thesis, Medicine thesis

Thesis type: Doctor of Philosophy
Completed: 2010
School: School of Medicine
Supervisor: Professor John Coveney