Associations between perceived healthy eating and intentions to change one's diet

When it comes to dietary behaviour change, intentions serve as an important determinant⁽¹⁾. One factor thought to influence someone's willingness to change is how healthy they view their diet. However, as many people are overly optimistic about the healthiness of their food choices⁽²⁾, there is a need to understand whether greater perceived healthy eating (PHE) reduces a person's intention to change, independent of their actual dietary intake. Therefore, this study aimed to examine the associations between PHE and intentions to change one's diet, controlling for diet quality and other covariates.

This study used data from the Irish National Adult Nutrition Survey (www.iuna.net) collected between 2008–2010 (n = 1077, female, 50.4%). PHE was measured using an average of 5 items adopted from previously validated tools (e.g. “Healthy eating is something I do frequently”). Intentions to change one's diet were assessed in three separate ways; Intention to 1) change overall diet 2) increase intake of fruit and vegetables, 3) reduce consumption of chocolate/sweets/savoury snacks. All items were measured on a 7-point Likert scale, ranging from 1 = strongly disagree to 7 = strongly agree. Food intakes were measured using a 4-day semi-weighed food diary. Each item was adjusted using a related dietary measure. The Nutrient-Rich Food Index (NRF9.3) was used for the overall diet, and total fruit and vegetable and sweet and savoury snack intakes were used for the other two items. A hierarchical multiple linear regression was used to examine the associations between PHE and each measure of intention to change one's diet. The first step included PHE only. The second step included the related dietary measure, sociodemographic factors (age, gender, education level, social class), BMI, lifestyle factors (smoking status, supplement use, vigorous activity), self-perceived health and weight, and satisfaction with food-related life.

PHE was negatively associated with intentions to change one's overall diet (β=−0.569, SE = 0.038; P < 0.001), increase fruit and vegetable intake (β=−0.140, SE = 0.032; P < 0.001), and reduce intake of chocolate/sweets/savoury snacks (β=−0.281, SE = 0.040; P < 0.001). The associations with intentions to change one's overall diet (β=−0.569, SE = 0.038; P < 0.001) and reduce intake of chocolate/ sweets/savoury snacks (β=−0.223, SE = 0.053; P < 0.001) remained significant after adjustment. However, the association with intentions to increase fruit and vegetable intake (β=−0.076, SE = 0.044; P = 0.085) was attenuated after adjustment.

The results suggest that, in general, the healthier people view their diet the fewer intention they have to change the way they eat, regardless of their actual diet quality. These negative associations were strongest for overall dietary change, suggesting PHE may have less influence on specific health-related intentions. This aligns with earlier studies showing that people who optimistically assess their diet's healthiness are less receptive to change⁽²⁾. Taken together, these findings suggest optimistic dietary perceptions may act as a cognitive barrier to shifting peoples' dietary habits.