Challenges in intervening to improve diet: Do inaccurate perceptions of diet limit the ability to tailor therapy?

Background: Inaccurate perceptions of self and diet are barriers to improving behaviors aimed at controlling weight. Though tailored interventions can effectively promote healthier eating habits, reliance on self-reported adherence may limit them from fully addressing these barriers. To examine this possibility, we assessed the accuracy of patients' perceptions of their diet and examined psychosocial characteristics of participants who highly underestimated their dietary fat content.

Methods: Hypertensive patients (n=221) were administered a 24-hour food recall and were asked to rate the fat content of their diet. The accuracy of participants' diet perception was evaluated using linear regression. Participants with high dietary fat content (>35%) were then grouped based on the accuracy of their perception. Wilcoxon rank-sum tests examined differences between groups in self-efficacy (SE), decisional balance, stage of change (SOC), and mental and social functioning.

Results: After controlling for demographic characteristics, perceived fat content predicted actual fat content (p<.05). Among participants with high-fat diets (n=64), 21 highly underestimated the fat content of their diet. Despite having poorer diets, these participants reported higher SE regarding their ability to adhere to diet recommendations (p<.001), higher SOC (p<.01), and may have lower social functioning (p=.07).

Discussion: While patients generally hold fairly accurate perceptions about their diets, certain patients with unhealthy diets have inaccurate perceptions of their dietary intake, a false sense of self-efficacy and incorrectly report more advanced SOC. These findings have substantial implications for behavioral interventions tailored to address dietary recommendations through self-reported adherence. Approaches to differentiate this subset of patients are warranted.