Mediating factors in dietary change: understanding the impact of a worksite nutrition intervention.

This report, based on 1,795 participants in the Next Step Trial, examines how a dietary intervention program affected mediating factors for dietary change. The model tested whether intervention increased predisposing (skills, knowledge, and beliefs) and enabling (social support and norms) factors for change and advanced participants into action and maintenance stages of change. The intervention significantly increased both predisposing factors for dietary change and the likelihood of moving into or remaining in action and maintenance stages of change. Changes in predisposing and enabling factors and stage of change at follow-up (regardless of stage at baseline) were associated with significant dietary change. Changes in mediating variables explained between 34% and 55% of the effects of the dietary intervention. These results support the value of measuring mediating factors as part of dietary intervention evaluations and suggest that interventions that target norms and eating environments in addition to skills and knowledge may further increase intervention effectiveness.