An examination of overweight young adults' adherence to their diets within the framework of the theory of planned behavior in the context of receiving dietitian support

Data were collected through face-to-face semi-structured interviews, alongside the administration of a demographic questionnaire, anthropometric measurement form, and a TPB-based scale assessing healthy eating and weight loss subdimensions. Quantitative data were analyzed using descriptive statistics and Ordinary Least Squares (OLS) regression; qualitative data were examined through thematic analysis. A statistically significant positive relationship was identified between positive attitudes toward healthy eating and behavioral intention (p = 0.048). No significant association was observed between subjective norms and intention (p = 0.83), and the relationship between perceived behavioral control and intention was positive yet not statistically significant (p = 0.62). Collectively, attitude, subjective norm, and perceived control demonstrated limited explanatory power for intention. In the weight loss subdimension, neither attitude nor subjective norm showed statistically significant associations with intention (p = 0.413; p = 0.901), while perceived behavioral control was found to be a significant positive predictor (p = 0.020). Thematic findings suggest that attitudes shaped by health concerns and body image, subjective norms influenced by social expectations, and perceived behavioral control strengthened through professional support played critical roles in the formation and maintenance of intention. Subjective norms were found to influence both attitude and perceived control. While social support enhanced perceived behavioral control, unsupportive environments diminished it. Participants' high self-efficacy, increased nutritional knowledge, and intrinsic motivation positively impacted their behavioral intentions. Additionally, dietitians' professional approach, experience, and gender, along with client expectations, emerged as influential external factors in sustaining dietary behavior. Overall, strong positive attitudes, motivating subjective norms, and high perceived behavioral control were associated with increased behavioral intention, thereby enhancing the likelihood of behavioral execution. Keywords: Attitude toward behavior, behavior, dietitian, perceived behavioral control, subjective norm, theory of planned behavior