title: A review and content analysis of engagement, functionality, aesthetics, information quality, and change techniques in the most popular commercial apps for weight management.
abstract: BACKGROUND
  There are thousands of apps promoting dietary improvement, increased physical activity (PA) and weight management. Despite a growing number of reviews in this area, popular apps have not been comprehensively analysed in terms of features related to engagement, functionality, aesthetics, information quality, and content, including the types of change techniques employed.
  
  
  METHODS
  The databases containing information about all Health and Fitness apps on GP and iTunes (7,954 and 25,491 apps) were downloaded in April 2015. Database filters were applied to select the most popular apps available in both stores. Two researchers screened the descriptions selecting only weight management apps. Features, app quality and content were independently assessed using the Mobile App Rating Scale (MARS) and previously-defined categories of techniques relevant to behaviour change. Inter-coder reliabilities were calculated, and correlations between features explored.
  
  
  RESULTS
  Of the 23 popular apps included in the review 16 were free (70%), 15 (65%) addressed weight control, diet and PA combined; 19 (83%) allowed behavioural tracking. On 5-point MARS scales, apps were of average quality (Md = 3.2, IQR = 1.4); "functionality" (Md = 4.0, IQR = 1.1) was the highest and "information quality" (Md = 2.0, IQR = 1.1) was the lowest domain. On average, 10 techniques were identified per app (range: 1-17) and of the 34 categories applied, goal setting and self-monitoring techniques were most frequently identified. App quality was positively correlated with number of techniques included (rho = .58, p < .01) and number of "technical" features (rho = .48, p < .05), which was also associated with the number of techniques included (rho = .61, p < .01). Apps that provided tracking used significantly more techniques than those that did not. Apps with automated tracking scored significantly higher in engagement, aesthetics, and overall MARS scores. Those that used change techniques previously associated with effectiveness (i.e., goal setting, self-monitoring and feedback) also had better "information quality".
  
  
  CONCLUSIONS
  Popular apps assessed have overall moderate quality and include behavioural tracking features and a range of change techniques associated with behaviour change. These apps may influence behaviour, although more attention to information quality and evidence-based content are warranted to improve their quality.
authors.affiliation: Department of Health Promotion and Community Health, American University of Beirut, Riad El Solh, Beirut, 1107 2020, Lebanon. marco.bardus@gmail.com.|Psychology Applied to Health group, University of Exeter Medical School, St Luke's Campus, Heavitree Road, Exeter, EX1 2LU, United Kingdom. marco.bardus@gmail.com.
authors.forename: Marco
authors.identifier: http://orcid.org/0000-0002-0707-7196
authors.initials: M
authors.lastname: Bardus
authors.affiliation: Psychology Applied to Health group, University of Exeter Medical School, St Luke's Campus, Heavitree Road, Exeter, EX1 2LU, United Kingdom.
authors.forename: Samantha B
authors.initials: SB
authors.lastname: van Beurden
authors.affiliation: Psychology Applied to Health group, University of Exeter Medical School, St Luke's Campus, Heavitree Road, Exeter, EX1 2LU, United Kingdom.
authors.forename: Jane R
authors.initials: JR
authors.lastname: Smith
authors.affiliation: Psychology Applied to Health group, University of Exeter Medical School, St Luke's Campus, Heavitree Road, Exeter, EX1 2LU, United Kingdom.
authors.forename: Charles
authors.initials: C
authors.lastname: Abraham
mesh_terms: D000068959:Body Weight Maintenance; D003132:Commerce; D004032:Diet; D004954:Esthetics; D015444:Exercise; D015438:Health Behavior; D006801:Humans; D063731:Mobile Applications / Q000592:standards*; D009765:Obesity / Q000517:prevention & control*
keywords: Behaviour change techniques; Mobile apps; Mobile health (mhealth); Smartphone; Weight loss; Weight management