JMIR Publications

ABSTRACT

Background:

Self-management smartphone applications have emerged as promising tools to encourage healthy behaviors. However, there remains a lack of empirical evidence supporting their efficacy in real-world settings. In this study, we utilized gym usage data from members of a major fitness club that operates gyms throughout Japan from January 2014 to December 2019.

Objective:

Our objective was to assess the extent to which a health and fitness self-management mobile application introduced to gym members on January 1, 2018 contributed to their weight loss. The app allows users to input information regarding diet, sleep, weight, and gym exercise such that they can receive personalized feedback from an AI chatbot to improve their health behaviors.

Methods:

We employed a linear regression to quantify the association between application usage and weight loss. The primary outcome of the study was the weight loss achieved by each gym user, which was calculated as the difference between their initial and final weights in kilograms, as recorded in the application. As a result, individuals who did not attend the gym or failed to use the mobile application at least twice during the study period were excluded from the analysis. The model accounted for age, gender, distance between the gym and the member’s residence, average weekly number of times a member used the gym, user’s gym membership length in weeks, average weekly number of times a member input information into the application, and the number of weeks that the application was used at least once.

Results:

Data from 26,589 participants were analyzed. Statistically significant associations between weight loss and two metrics related to application usage (i.e., the average weekly frequency of usage and the total number of weeks in which the application was used at least once) were detected. One input per week was found to be associated with a loss of 62.1g (95% confidence interval: 53.8 to 70.5), and one week of application use was associated with 21.7g (20.5 to 22.9) of weight loss from the day of the first input to that of the final input to the application. Furthermore, the average number of times that a member used the gym weekly was also shown to be statistically significantly associated with weight loss: one use per week was associated with 255.5 g (228.5 to 282.6) of weight loss.

Conclusions:

Our empirical study demonstrated a significant association between weight loss among gym members and not only the frequency of weekly gym use, but also the use of a health and fitness self-management application. However, further work is needed to examine the mechanisms through which mobile applications affect health behaviors, and to identify the specific application features that are most effective in promoting weight loss.