Background: This report examines psychosocial factors related to selection of healthful diets. Understanding why people select healthful diets can lead to rational design and evaluation of nutrition intervention programs.
Methods: Data are from 16,287 respondents to the baseline survey for the Working Well Trial, a randomized, controlled trial of worksite-based health promotion. The psychosocial constructs we measured were predisposing factors (beliefs, perceived benefits, and motivation; 5 items, Cronbach's alpha = 0.65) and enabling factors (barriers, norms, and social support; 6 items, Cronbach's alpha = 0.57). The healthful diet outcomes were intakes of fat, fiber, and servings of fruits and vegetables (from a food frequency questionnaire) and intention and self-efficacy to decrease fat and increase fruits and vegetables.
Results: Based on a 5-point scale (1 = low to 5 = high), the mean predisposing factor scale score was much higher than the enabling factor scale score (3.77 vs 2.50, P < 0.001). Comparing respondents in the highest category of the predisposing scale to those in the lowest, mean percentage of energy from fat was 22.4% lower (-9 percentage points), fiber was 85.2% higher (+4.6 g/1,000 kcal), and fruits and vegetables were 100% higher (+1.6 servings/day) (all trends, P < 0.001). Associations were similar, but much weaker, for the enabling scale. Multiple regression models, which included covariates related to diet and the predisposing and enabling scales, explained a total of between 13 and 26% of the variance in diet and intention to change diet. After control for covariates, the predisposing scale remained a significant and strong predictor of diet and intention to change diet but the enabling scale explained small and nonsignificant amounts of variance.
Conclusions: Predisposing factors are strong predictors of current diet and intention to change diet. Final results from the Working Well Trial will provide more information on whether enabling factors can be enhanced by intervention and whether these changes result in healthier eating patterns.