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Intervention engagement moderates the dose-response relationships in a dietary intervention
Lippke, Sonia Corbet, Jana M. Lange, Daniela Parschau, Linda Schwarzer, Ralf
Lippke, Sonia
Corbet, Jana M.
Lange, Daniela
Parschau, Linda
Schwarzer, Ralf
Abstract
Behavioral interventions could lead to changes in behavior through changes in a mediator. This dose–response relationship might only hold true for those participants who are actively engaged in interventions. This Internet study investigated the role of engagement in a planning intervention to promote fruit and vegetable consumption in addition to testing the intervention effect on planning and behavior. A sample of 701 adults (mean = 38.71 years, 81% women) were randomly assigned either to a planning intervention (experimental group) or to one of 2 control conditions (untreated waiting list control group or placebo active control group). Moderated mediation analyses were carried out. Significant changes over time and time × group effects revealed the effectiveness of the intervention. The effect of the intervention (time 1) on changes in behavior (time 3; 1 month after the personal deadline study participants set for themselves to start implementing their plans) was mediated by changes in planning (time 2; 1 week the personal deadline). Effects of planning on behavior were documented only at a moderate level of intervention engagement. This indicates an inverse U-shaped dose–response effect. Thus, examining participants’ intervention engagement allows for a more careful evaluation of why some interventions work and others do not.
Keywords
moderated mediation, randomized controlled trial, intentions, planning, nutrition
Date
2016
Type
Journal article
Journal
Dose-Response
Book
Volume
14
Issue
1
Page Range
1-10
Article Number
ACU Department
Collections
Relation URI
Source URL
Event URL
Open Access Status
Open access
License
CC BY-NC 3.0
File Access
Open