Timing of dietary change in response to a telephone counseling intervention: Evidence from the WHEL study

Objective: Little is known about temporal patterns of diet change within interventions, nor about predictors of early and sustained successful change. Social-cognitive theory asserts that early successes in achieving behavior change increase self-efficacy, leading to longer-term success. Design: The authors conducted exploratory cluster analyses using dietary data from the first month of the telephone counseling intervention of the Women's Healthy Eating and Living (WHEL) Study. Main Outcome Measure: Change in dietary pattern at three early intervention timepoints. Results: Three clusters were identified: Cluster 1 (25%) was close to meeting study goals at baseline, but still made major changes; Cluster 2 (49%) and Cluster 3 (26%) were not achieving study goals at baseline, but Cluster 2 made substantial immediate changes, while Cluster 3 changed their diet more gradually. Baseline demographic and behavioral variables were associated with cluster membership; however, the strongest predictors of cluster were self-efficacy, motivation, and approaches to study goals. Cluster membership predicted dietary pattern at 12 months. Conclusion: These data suggest that a one-on-one telephone counseling intervention that is intensive in the early weeks may maximize the level of change achieved in a study.