Navigating the complexity: a comment on difficulties in conducting systematic reviews to evaluate the effectiveness of behaviour change interventions.

Behaviour change interventions are widely applied across diverse domains to modify behaviours and improve outcomes, including but not limited to physical activity, sedentary behaviour, and nutrition. Systematic review of trials of behaviour change interventions often aim to determine both their overall effectiveness and the specific components driving behaviour change. The Behaviour Change Technique Taxonomy v1 (BCTTv1) is a useful framework for coding the individual Behaviour Change Techniques (BCTs) within an intervention. This commentary highlights key methodological challenges in conducting a systematic review of behaviour change interventions. It calls for collaboration in developing clear and consistent methodological guidance to enhance the rigor of systematic reviews to optimise behaviour change interventions.