OBJECTIVE:
to assess the effect of health education intervention programme based on Theory of Planned Behaviour (TPB) on unhealthy dietary behaviour as a lifestyle risk factor for non-communicable diseases (NCDs). Design: pretest posttest quasi-experimental at baseline and immediately after the intervention. Setting: motor parks in Sabon-gari local government area, Kaduna state, Nigeria. Participants: a total of 50 commercial drivers (all males), 25 each in the experimental and control groups selected through convenience, purposive and availability sampling techniques. Intervention: over a period of six weeks, participants received health education on unhealthy dietary behaviour as a lifestyle risk factor for NCDs. The intervention was planned based on the TPB and delivered in Hausa language using lecture and discussion methods. Main outcome measure(s): attitude, subjective norms, perceived behavioral control and behavioral intention towards unhealthy dietary behaviors. Analysis: Fisher’s exact test was used to compare the demographic characteristics of respondents and mixed ANOVA was used to analyse differences, at 0.05 level of significance, eta effect sizes were analyzed.

RESULTS:
there was significant difference both in the within group and between group analysis of each TPB construct and in their total score with P < 0.001 with substantial effect sizes in all cases. Conclusion and implications: TPB-based intervention health education can be a valuable tool for fostering healthier dietary behaviours in occupational settings and should be integrated into workplace wellness initiatives, particularly for groups like commercial drivers who face unique health risks. Key Words: Theory of planned behaviour, Attitude, Subjective norms, Perceived behavioural control, Behavioural intention, Unhealthy diet, Commercial drivers.