STAGES OF CHANGE FOR REDUCING DIETARY-FAT INTAKE OVER 18 MONTHS

Objective To describe the stages of change that take place over 18 mon ths, using the criterion of fat intake less than or equal to 30% of to tal energy to define effective action and to investigate the effect of a single dietary feedback report on dietary fat reduction. Design Sub jects were randomly assigned to experimental or control conditions and assessed at 0, 6, 12, and 18 months for fat intake and stage of chang e. Subjects in the experiment group received 1 feedback report at base line; all subjects received a report at 12 months. Subjects Potential subjects (n=614) were recruited by mail from a random sample of nonsmo king adults (32% response rate). Subjects were excluded if consuming l ess than or equal to 30% of energy from fat or if pregnant or lactatin g (n=145). Although 83% of subjects (n=389) completed the 18-month stu dy, only 296 provided complete data for all time points. The study was restricted to these 296. Intervention Dietary feedback reports plus b rief educational materials were provided following the experiment desi gn. Analyses Repeated measures analysis of variance with fat intake (p ercent of energy from fat) as the dependent variable and baseline stag e and condition as independent variables. In addition, t tests were us ed to compare groups at specific time points. Results There was a main effect for time (F-3,F-286=39, P<.0001) and baseline stage (F-3,F-286 =24, P<.0001), but no effect of feedback. There was a time-by-feedback interaction (F-4,F-286=4.7, P<.01). There was a short-term effect of feedback over 6 months (t=3.8, P<.001), but this effect was not signif icant at other time points. About 9% to 12% of subjects in the precont emplation or contemplation stages, 24% of subjects in the preparation stage, and 40% of unclassified subjects at baseline progressed to the action stage by 18 months. Between 12 and 18 months, subjects progress ing at least 1 stage reduced their fat intake to a greater extent than subjects who failed to progress (t=5.1, P<.0001). Implications Interv entions targeted to stage of change have the potential for acceleratin g the rate of change for dietary fat reduction, but reaching the goal of fat intake less than or equal to 30% of total energy may require mo re intensive interventions than a single dietary feedback report.