Using the Theory of Planned Behaviour to Explain Young New Zealand Adults' Restaurant Calorie Consumption

Abstract

Aims: The prevalence of obesity is increasing among the New Zealand adult population. The current study aimed to measure the effectiveness of a potential obesity control intervention: providing point-of-purchase restaurant calorie information to increase the informed choice of lower-calorie meals. The study also aimed to help understand young New Zealand adults' restaurant calorie consumption behaviour using the Theory of Planned Behaviour as the guiding theoretical framework, while simultaneously testing the theory's predictive validity of the target behaviour and whether the predictive validity may be further enhanced. Methods: A randomised two-group post-test experiment was used to measure the effectiveness of the intervention: a web-based behavioural task was administered to 439 University of Auckland undergraduates who were randomly assigned to choose from an online breakfast and lunch menu which either both included or did not include calorie information. Also, to account for social setting influences, the two menus were accompanied with two randomly-assigned scenarios: dining with family and with friends. For the second aim, a web-based Theory of Planned Behaviour questionnaire was administered following the behavioural task. The potential enhancement of the theory‟s predictive validity was investigated by including measures of three additional constructs: affection, moral norm and past behaviour. Prior to the questionnaire, a salient beliefs elicitation questionnaire was administered to a sample of twenty-four undergraduates, where the elicited salient beliefs were included in the subsequent questionnaire. Data analysis was conducted using relevant statistical tests: bivariate correlations, t-tests and standard linear and hierarchical multiple regressions.