Behavior Change Theory Taxonomy Analysis of Smartphone Apps for Fitness, Nutrition, and Weight Loss

Abstract

A majority of Americans do not meet physical activity or nutrition guidelines for health. Convenient interventions to support healthy behaviors may be beneficial. Smartphone use has become ubiquitous, with apps that are an integral part of life for many. The health and fitness category of apps is robust and growing, but the potential for these apps to affect health behavior change is poorly understood. PURPOSE: To evaluate top-ranked fitness, nutrition, and weight-loss smartphone apps for incorporation of evidence- based behavior change strategies. METHODS: Two investigators coded descriptions of the 150 top-ranked “free” apps in the health and fitness category of the US iOS app store for evidence of health behavior change strategies using the Behavior Change Technique (BCT) Taxonomy (v1). Prevalence of taxonomy items were calculated and Pearson correlations were estimated for the relationship between BCTs per app and customer ranking, as well as for the relationship between BCTs per app and app store ranking. Significance was set at p < 0.05. RESULTS: 71 app descriptions were identified as fitness, nutrition, and/or weight-loss focused. Of those, 45.1% incorporated goals and planning; 57.7% incorporated feedback and monitoring; 56.8% incorporated social support; 29.6% incorporated comparison of behavior; 29.6% incorporated shaping knowledge; 22.5% incorporated associations; 11.6% incorporated reward and threat; 9.9% incorporated antecedents; and 5.6% incorporated natural consequence. Only 17 of the 93 techniques in the BCT taxonomy were utilized across all coded apps. There was a trend towards a weak negative correlation between number of BCTs per app and app store ranking (r = -0.22, p = 0.06) and no significant correlation between number of BCTs and customer rating (r = -0.02, p = 0.87). 45.1% of the “free” apps offered a premium version, in addition, and 11.3% required a paid subscription after download. CONCLUSIONS: Goal planning, monitoring, feedback, and social support were the most common strategies found in the popular fitness, weight-loss, and nutrition apps, though more must be learned about their effectiveness. Furthermore, there is potential to incorporate a greater variety of health behavior change techniques.