Young adults' intention to eat healthy food:: Extending the theory of planned behaviour

The present study predicts adults' intention to eat healthily, using the theory of planned behaviour (TPB) and additive and moderating effects of role identity, group norms and group identification, derived from identity theory and self categorisation theory. A total of 735, 25 years old adults participated in a mailed questionnaire survey in 1997. The TPB explained 52% of the variance in young adults' decision to eat healthily, with perceived behavioural control and subjective norms being the strongest (beta = .56, p < .001) and weakest (beta =.05, p < .005) determinants, respectively. Although, role identity accounted for an additional amount of 4% of the variance in behavioural intention, past behaviour did not moderate the impact of role identity on intention, as hypothesised. Neither perceived group norm nor group identification added to the prediction of intention over and above the TPB. However, group identification was found to act as a moderator on the relation between group norm and behavioural intention in the predicted direction. The wider social context seems to play a stronger role for the formation of adults' healthy eating decisions than indicated by the TPB.