Using theory to develop and test interventions to promote changes in health behaviour: evidence, issues, and recommendations

• The evidence that using theory produces greater health behaviour change is mixed.
• Interventions often achieve small/moderate behaviour change unexplained by theory.
• Up to 89% of health interventions do not appear to be based on theory.
• Many ‘theory-based’ interventions do not fully apply the underlying theory.
• Many earlier reviews do not account for the extent to which theory is applied.

Using theory to develop health behaviour interventions provides a useful framework to accumulate evidence and has been associated with larger changes in health behaviour. The present review suggests, however, that the evidence that using theory in this way produces greater health behaviour change is mixed. Furthermore, evaluating such evidence is difficult because: first, a significant proportion of interventions are not based on theory; second, those that are, tend not to apply the theory extensively; third, theory-based and comparison groups can be confounded; and fourth, interventions may be based on multiple theories. Such difficulties delay theory evolution and the development of interventions that are capable of achieving significant and sustained changes in health behaviours. Recommendations are made to address these issues.