Fruit and Vegetable Intake: the Interplay of Planning, Social Support, and Sex.

PURPOSE: Intention and planning are important predictors of dietary change. However, little attention has been given yet to the relationship between them as a function of other social-cognitive factors and their interplay with socio-demographics such as sex. METHODS: In an observational study (1520 women, 430 men) with two measurement points in time, intention (predictor), planning (mediator), social support (first moderator), and sex (second moderator) were assessed to predict changes in diet separately for fruit and vegetable intake. RESULTS: All predictors had a main effect on fruit intake but no interactions emerged. For vegetable intake, the mediation-chain was qualified by a three-way interaction: for women, the lower the perceived social support, the more the translation of planning into behavior; for men, the higher the perceived social support, the more the translation of planning into behavior. CONCLUSIONS: Even though intention and planning are predictors of dietary change, they operate differently under specific conditions (level of social support), for specific subgroups (men vs. women), and for different target behaviors (fruit vs. vegetable intake). These results suggest to further examine the mechanisms by which intentions are translated into behavior via planning.

The interplay of intention, autonomy, and sex with dietary planning: A conditional process model to predict fruit and vegetable intake.

OBJECTIVES: Dietary intentions are supposed to engender planning processes, which in turn stimulate dietary behaviour change. However, some studies failed to find such mediation effects, which suggest more complex and not yet unravelled relationships between these factors. One explanation may be that mediation works better under certain circumstances or only for specific subgroups. This study addresses this reasoning by examining autonomy beliefs and sex as putative moderators of the hypothesized mediation chain. DESIGN AND METHODS: In a longitudinal design with three measurement points in time (1 week and 1 month apart), 912 women and 214 men were surveyed. Planning, intention, dietary autonomy beliefs, and sex were used to predict fruit and vegetable intake within a conditional process model designed to identify mechanisms of change. RESULTS: The intention-planning-behaviour chain was qualified by a triple interaction involving autonomy beliefs and sex as moderators between intention and planning. Higher dietary autonomy resulted in higher levels of planning fruit and vegetable intake. For men, even in case of higher intention, at least medium levels of autonomy beliefs were necessary to facilitate planning processes. For women, already lower levels of autonomy beliefs can engender postintentional planning strategies and seem to even compensate lower intention. CONCLUSIONS: Intention and planning are key predictors of dietary change. However, these variables work better under specific conditions (with a sufficient level of autonomy), and differently in subgroups (men vs. women). These results may explain the inconsistent findings of previous studies on the mediating effect of planning and allow for a better description of the mechanisms by which intentions may influence behaviour. Statement of contribution What is already known on this subject? The adoption of health-enhancing dietary behaviours can be facilitated by intentions and planning. Planning to eat more fruit and vegetable helps to translate intentions into actual consumption. Fruit and vegetable intake levels are higher in women than in men. What does this study add? Dietary intentions engender more likely planning processes when perceived autonomy concerning food consumption is high. Dietary autonomy beliefs and sex moderate the intention-planning-behaviour chain. Among men, dietary planning is highest when both intentions and autonomy are high.