title: A systematic review and meta-analysis of applications of the Self-Report Habit Index to nutrition and physical activity behaviours.
abstract: BACKGROUND
  Health behaviour models typically neglect habitual action. The Self-Report Habit Index (SRHI) permits synthesis of evidence of the influence of habit on behaviour.
  
  
  OBJECTIVE
  The purpose of this study is to review evidence around mean habit strength, habit-behaviour correlations, and habit x intention interactions, from applications of the SRHI to dietary, physical activity, and active travel behaviour.
  
  
  METHODS
  Electronic database searches identified 126 potentially relevant papers. Twenty-two papers (21 datasets) passed eligibility screening. Mean scores and correlations were meta-analysed using fixed, random and mixed effects, and interactions were synthesised via narrative review.
  
  
  RESULTS
  Twenty-three habit-behaviour correlations and nine habit x intention interaction tests were found. Typical habit strength was located around the SRHI midpoint. Weighted habit-behaviour effects were medium-to-strong (fixed: r + = 0.44; random: r + = 0.46). Eight tests found that habit moderated the intention-behaviour relation.
  
  
  CONCLUSIONS
  More comprehensive understanding of nutrition and activity behaviours will be achieved by accounting for habitual responses to contextual cues.
authors.affiliation: Health Behaviour Research Centre, University College London, 1-19 Torrington Place, London, UK. b.gardnersood@ucl.ac.uk
authors.forename: Benjamin
authors.initials: B
authors.lastname: Gardner
authors.forename: Gert-Jan
authors.initials: GJ
authors.lastname: de Bruijn
authors.forename: Phillippa
authors.initials: P
authors.lastname: Lally
mesh_terms: D006184:Habits; D015438:Health Behavior; D006801:Humans; D009043:Motor Activity; D009752:Nutritional Status; D057566:Self Report; D014195:Travel / Q000706:statistics & numerical data