Action and inaction in multi-behaviour recommendations: a meta-analysis of lifestyle interventions.

This meta-analysis examined theoretical predictions about the effects of different combinations of action (e.g., start an exercise regime) and of inaction (e.g., reduce screen time, rest in between weight lifting series) recommendations in smoking, diet, and physical activity multiple-domain interventions. The synthesis included 150 research reports of interventions promoting multiple behaviour domain change and measuring change at the most immediate follow-up. The main outcome measure was an indicator of overall change that combined behavioural and clinical effects. There were two main findings. First, as predicted, interventions produced the highest level of change when they included a predominance of recommendations along one behavioural dimension (i.e., predominantly inaction or predominantly action). Unexpectedly, within interventions with predominant action or inaction recommendations, those including predominantly inaction recommendations had greater efficacy than those including predominantly action recommendations. This effect, however, was limited to interventions in the diet and exercise domains, but reversed (greater efficacy for interventions with predominant action vs. inaction recommendations) in the smoking domain. These findings provide important insights on how to best combine recommendations when interventions target clusters of health behaviours.