Effect of healthy dietary intention-behavior (in)consistency on depression and anxiety in the process of behavior change.

Although an increasing number of people are now committed to pursuing a healthy diet, it remains unclear how mental health changes during this process. The present study aimed to examine the combined effect of healthy dietary intention and behavior on depression and anxiety across two sub-studies. This study consisted of two parts: a cross-sectional survey (Study 1) involving 1,433 college students and an 11-day daily diary study (Study 2) with 117 college students. Polynomial regression and response surface analysis indicated that in cases of congruence, individuals' intention and behavior align at a high level and were associated with lower levels of depression and anxiety in the motivational phase but were not found similar association in the volitional phase. In cases of incongruence, individuals with high intention-low behavior tend to experience lower levels of depression and anxiety in the motivational phase. However, individuals with high intention-low behavior tend to experience higher levels of depression and anxiety in the volitional phase. These findings not only enrich the current understanding of diet and health but also contribute to the development of holistic strategies for promoting a healthy diet.