Abstract
Background:
Research into interventions based on mobile health (m-Health) applications (apps) has attracted considerable attention among researchers; however, most previous studies have focused on research-led apps and their effectiveness when applied to overweight/obese adults. There remains a paucity of research on the attitudes of typical consumers toward the adoption of m-Health apps for weight management. This study adopted the tenets of the extended unified theory of acceptance and use of technology 2 (UTAUT2) as the theoretical foundation in developing a model that integrates personal innovativeness (PI) and network externality (NE) in seeking to identify the factors with the most pronounced effect on one's intention to use an artificial intelligence-powered weight loss and health management app.
Materials and Methods:
An online survey was conducted for Taiwanese participants aged ≥21 years from May 23 to June 30, 2018. Hypotheses were tested using structural equation modeling.
Results:
In the analysis of 458 responses, the proposed research model explained 75.5% of variance in behavioral intention (BI). Habit was the independent variable with the strongest performance in predicting user intention, followed by PI, NE, and performance expectancy (PE). Social influence weakly affects user intention through PE. In multi-group analysis, education was shown to exert a moderating influence on some of the relationships hypothesized in the model.
Conclusions:
The empirically validated model in this study provides insights into the primary determinants of user intention toward the adoption of m-Health app for weight loss and health management. The theoretical and practical implications are relevant to researchers seeking to extend the applicability of the UTAUT2 model to health apps as well as practitioners seeking to promote the adoption of m-Health apps. In the future, researchers could extend the model to assess the effects of BI on actual use behavior.
Introduction
Rapid developments in mobile internet connectivity and increased processing power have shifted the focus from desktop and laptop computers to smartphones. The Statista Global Smartphone Penetration report projected that 37% of the world's population will own a smartphone by 2020. 1 Mobile health (m-Health) is a nascent technology in which smartphones are used to remotely collect continuous biological and behavioral data, deliver health information, and provide recommendations. m-Health systems have been shown to promote disease prevention, improve treatment compliance, and reduce medical expenses at the individual level. 2,3 There is every likelihood that m-Health could provide continuous monitoring of chronic diseases at the population level, 4 and the World Health Organization reported that this technology has the potential to transform the delivery of health services across the world. 5 Mobile applications (apps) are software programs designed to run on mobile devices, such as smartphones or tablets. There are two main types of m-Health apps 6,7 : (1) m-Health apps that are regulated are developed specifically for clinical use and approved by the United States Food and Drug Administration (FDA) or similar regulatory body and (2) m-Health apps that are unregulated are developed for personal use outside the context of clinical interactions (i.e., without the need for certification). One study reported that in 2017, there were ∼318,000 m-Health apps available on Apple's App Store and Google Play. The rapid expansion in m-Health apps that focus on managing health already accounts for 40% of all apps. 8
It has reported that 65% of the world's population lives in countries where being overweight is a more pressing health concern than is being underweight. Globally, the fifth leading cause of death is obesity, 9 by increasing the risk of many serious diseases. 10 Weight loss can reduce the risks associated with obesity. Diet and exercise play crucial roles in losing weight and keeping it off. 11,12 m-Health apps send overweight/obese individuals cognitive, emotional, and behavioral responses aimed at facilitating weight management. 13 –16 The convenience and ubiquity of smartphones makes them an ideal vehicle by which to use m-Health apps for the self-monitoring of one's health throughout the day. 17
Research into m-Health app interventions has attracted considerable attention among researchers; most previous studies have focused primarily on the effectiveness of research-led m-HealTh apt interventions for individuals who are overweight or obese 14,18 –20 ; other research has related to the use of health apps and been aimed at individuals in more targeted groups, such as clinicians to assist patients with diabetes and/or weight problems 21 or college students to maintain their health and fitness regimens. 22 However, there is a paucity of research into the attitudes of the general public on the adoption of m-Health apps for weight management. The adoption of such technology could have significant implications for public health practices 3,5 ; therefore, it is of crucial importance to identify the predictors of m-Health app usage. In this study, we used the extended unified theory of acceptance and use of technology 2 (UTAUT2) model as the theoretical basis for the development of a model integrating the theories of personal innovativeness (PI) and network externality (NE). The model was developed primarily to identify the factors with the most pronounced effect on one's intention to adopt a mobile app for weight loss and health management. The proposed app features artificial intelligence (AI) technology to facilitate accurate analysis/health consultations in real time (i.e., tracking of diet and exercise data and guidance), proactive weight prediction, and the sharing of data on social media.
Theoretical Framework and Hypotheses
Venkatesh et al. 23 proposed the UTAUT model, which was derived from eight well-known information technology (IT) acceptance and usage models. The UTAUT model outlines how four independent variables affect the behavioral intentions (BI) of the user to adopt a given technology. The variables include performance expectancy (PE), effort expectancy, social influence (SI), and facilitating conditions (FC). The UTAUT model was developed in the organizational context wherein the use of a technology can be an organizational mandate. The UTAUT model was updated in the form of the UTAUT2 to fit it within the consumer use context by adding three additional variables: hedonic motivation (HM), price value, and habit (HT). 24 The UTAUT2 model has been empirically tested in many technological contexts. 25 –29
In this study, we adopted the UTAUT2 model as the theoretical basis in conjunction with the theories of PI 30,31 and NE 32 to identify the determinants of user intention to use an AI-powered weight loss and health management app. We theorized that PE, effort expectancy (EE), PI, SI, NE, HM, FC, and HT could serve as determinants of BI to adopt an AI-powered weight loss and health management app. Figure 1 depicts our research model and proposed hypotheses. Our research model can be expressed using the following structural equation:

Proposed UTAUT2-based model and estimated path coefficients between constructs. Dotted lines indicate nonsignificant paths. ***p < 0.001, **p < 0.01, *p < 0.05. BI, behavioral intention; EE, effort expectancy; FC, facilitating conditions; HM, hedonic motivation; HT, habit; NE, network externality; PI, personal innovativeness; PE, performance expectancy; SI, social influence; UTAUT2, unified theory of acceptance and use of technology 2.
where X and ß, respectively, refer to the construct and the path coefficient. The effect of Xi on Xj is denoted by path coefficient βji.
Performance expectancy
PE is defined as “the degree to which using a technology will provide benefits to consumers in performing certain activities.” 24 Researchers have previously shown that PE plays a crucial role in the use of m-Health apps for monitoring heart failure, 33 overall fitness, 28 and health information. 34 Therefore, we hypothesize the following:
Effort expectancy
EE refers to “the degree of ease associated with consumers' use of technology.” 24 Previous research has shown that effort expectancy is an important determinant of consumer's intention to use m-Health app for cardiac rehabilitation, 35 mobile health care services, 36 and health information. 34 Therefore, we hypothesize the following:
Personal innovativeness
PI is defined as “the degree to which an individual is receptive to new ideas and makes innovation decisions independently.” 30 A growing body of empirical evidence has shown that PI is an important factor in the adoption of new consumer products, 37 mobile commerce, 38 mobile payment, 39 and mobile diet apps. 40 It also appears that PI is an antecedent of intention to use information and communication technology (ICT). 25,41,42 Therefore, we hypothesize the following:
Social influence
SI refers to “which consumers perceive that important others (e.g., family and friends) believe they should use a particular technology.” 24 Previous research has shown that SI is a significant predictor of intention to use m-Health services, 36 health apps, 22 and mobile diet apps. 40 It has also been shown that SI is an antecedent of intention to use personal computer system 43 and ICT products. 38,44 Therefore, we hypothesize the following:
Network externality
NE refers to “an increase in the value of a product or service as the number of users of that product or service increases.” 32 Researchers have demonstrated the importance of NE in influencing the acceptance and use of many ICT products and services. 45 –47 In many ICT markets, consumer expectations concerning the current and future installed customer base and the resulting externality play essential roles in the adoption of a given product or service. 48 Therefore, we hypothesize the following:
Hedonic motivation
HM is defined as “the fun or pleasure derived from using a technology.” 24,49 It has been shown that HM (enjoyment and playfulness) is an important factor affecting the acceptance and use of IT products. 28,50 Most health-related apps are not designed for hedonic purposes; however, it is possible in some situations to integrate gamification within an app to make it more engaging and entertaining for users. 26,28,51 Therefore, we hypothesize the following:
Facilitating conditions
FC refer to “consumers' perceptions of the resources and support available to perform a behavior.” 24 Researchers have shown that many FC (e.g., individual competency, online tutorials, internet connection quality) can influence the intentions of users in adopting ICT products. 24,27,33 Therefore, we make the following hypothesis:
Habit
HT is defined as “the degree to which people tend to perform behaviors automatically owing to learning.” 24 HT is a learned behavior that is developed through repeated practice until it can be performed automatically and unconsciously. 52 Habitual behavior is also applicable in the IT field. 53,54 Researchers in the domain of health care have identified habit as a significant predictor of one's intention to use m-Health apps for monitoring heart failure 33 and for cardiac rehabilitation. 35 Therefore, we hypothesize the following:
H8: HT will have a significant influence on BI.
Materials and Methods
The proposed model includes nine constructs, each of which was measured using multiple items. The questionnaire items (Table 1) were adapted from extant literature with minor wording modifications to fit within the context of the study. 23,24,32,44,55 The questionnaire items were measured using a 5-point Likert scale ranging from 1 = strongly disagree to 5 = strongly agree. The content validity of the questionnaire was evaluated by a panel of 11 experts (2 academics, 1 market research analyst, 1 physician, 3 app users, and 4 industry experts). Based on the feedback of the panelists, the questionnaire was further refined in terms of structure and clarity, and ambiguous wording was modified. After receiving approval from the National Taiwan University Hospital's Institutional Review Board, the survey was conducted between May 23 and June 30, 2018. Data were collected using convenience sampling. The participants were recruited via social media (e.g., Facebook and discussion forums), messaging apps (e.g., LINE 56 and Facebook Messenger), and e-mail. The survey targeted Taiwanese individuals aged ≥21 years who had experience in the use of mobile internet technologies. Hypotheses were tested using structural equation modeling. In accordance with the two-step approach outlined in a previous study, 57 we employed confirmatory factor analysis (CFA) to assess the adequacy of the measurement model. The structural model was then examined to confirm the hypothesized causal relationships among latent constructs. All data analysis was performed using SPSS version 22.0 and AMOS version 24.0.
Measurement Items
app, application; BI, behavioral intention; EE, effort expectancy; FC, facilitating conditions; HM, hedonic motivation; HT, habit; NE, network externality; PI, personal innovativeness; PE, performance expectancy; SI, social influence.
Results
Descriptive Analysis
A total of 557 responses were obtained using the online survey platform Google Forms. Among these, 99 were excluded due to incomplete answers, which yielded 458 valid samples. The respondents were almost equally split in terms of gender and covered a wide range of occupations. Among the respondents, 48.9% were aged 21–30 years, 57.2% possessed a master's degree or higher, 52.9% had experience in using health and fitness apps and/or wearable devices, and 81.3% had more than 5 years experience in the use of mobile internet technologies. Table 2 lists the descriptive statistics of the respondents.
Demographic Characteristics of Respondents (n = 458)
Measurement Model
The measurement model was verified by assessing construct reliability, convergent validity, and discriminant validity. Cronbach's alpha was used to assess reliability, and CFA was used to assess the validity of the constructs. In an initial CFA, detailed analysis of regression weights, standardized regression weights, model fit indices, and squared multiple correlations (SMC) estimates led to the elimination of two items used to measure PI (PI3) and SI (SI4) from further consideration, due to the fact that the SMC values of PI3 (0.021) and SI4 (0.262) failed to meet the threshold of 0.5. The measurement model was then revised and retested. In a second CFA, the SMC values of the remaining 30 items exceeded the threshold of 0.5, indicating good item reliability (Table 3). Data were also checked for univariate and multivariate normality. As shown in Table 3, the absolute skewness was less than the threshold of 2.0 and kurtosis was less than the threshold of 7.0, indicating the univariate normal distribution of the data. Table 3 also shows that the Mardia's coefficient was less than 960, indicating the multivariate normal distribution of the data. Note that this was computed as P(P + 2), where P is equal to the number of observed variables. 58 The results of normality testing revealed that our data followed a normal distribution. Thus, maximum likelihood estimation was used to estimate model fitting.
Confirmatory Factor Analysis Results of Proposed Measurement Model
α, Cronbach's α; AVE, average variance extracted; CR, composite reliability; EV, error variance; KU, kurtosis; M, mean; SD, standard deviation; SE, standard error; SFL(t), standardized factor loading (t-value); SK, skewness; SMC, squared multiple correlation.
As shown in Table 3, the Cronbach's alpha of each construct exceeded the recommended cutoff of 0.7, indicating good reliability. Convergent validity was confirmed by the fact that the standardized factor loadings exceeded the recommended cutoff value of 0.7 and the t-values were statistically significant. The average variance extracted values for each construct exceeded the cutoff value of 0.5, and the composite reliability values exceeded the cutoff value of 0.7. As shown in Table 4, discriminant validity was also confirmed by the fact that the diagonal values exceeded the off-diagonal values. Six fit indices were used to assess how well the proposed model fit the sample data: chi-square/df ratio (χ 2 /df), goodness-of-fit index (GFI), adjust goodness-of-fit index (AGFI), root mean square error of approximation (RMSEA), normed fit index (NFI), and comparative fit index (CFI); their acceptable thresholds were <3, >0.8, >0.8, <0.08, >0.9, and >0.9, respectively. All fit indices were within the range of permissible values (χ 2 /df = 2.333, GFI = 0.883, AGFI = 0.852, RMSEA = 0.054, NFI = 0.924, and CFI = 0.955), indicating that our proposed model fit the data adequately.
Matrix of Correlation and the Square Root of Average Variance Extracted (in Bold)
Correlation is significant at the 0.01 level (two-tailed).
Structural Model
Based on the results of CFA, the degree to which the data fit the structural model was deemed acceptable (χ
2
/df = 2.823, GFI = 0.857, AGFI = 0.824, RMSEA = 0.063, NFI = 0.905, and CFI = 0.936). Figure 1 provides a summary presentation of the empirical results for our proposed model. In terms of hypothesized relationship, H1, H3a, H3b, H3c, H4a, H4b, H5, and H8 were supported, whereas H2, H4c, H6, and H7 were not supported. The observed R2 values for BI, PE, and EE (0.755, 0.414, and 0.296, respectively) exceeded the recommended value of 0.2. As illustrated in Figure 1, PI, PE, NE, and HT had a direct effect on BI. Bootstrapping
59
was used to examine the indirect effects. The number of bootstrap samples was set at 2,000 with a 95% bias-corrected confidence interval (CI). The indirect effects of PI on BI through PE (β = 0.047, 95% CI = 0.004–0.099, p < 0.05) and the indirect effects of SI on BI through PE (β = 0.029, 95% CI = 0.003–0.065, p < 0.05) were statistically significant. Thus, our research model can be specified using the following equation:
where
Multi-Group Analysis
As shown in Table 2, more than 57% of the 458 respondents held a master's degree or higher. Note that education influenced PI in the adoption of new products
31,37
and moderated the effects of UTAUT2 predictors on BI to use ICT products.
60
Thus, we examined the moderating effect of education on BI by dividing the data set (n = 458) into two groups: group M (n = 262) with a master's degree or higher and group B (n = 196) with a bachelor's degree or below. Our results from multi-group analysis
61
revealed a significant difference between group M and group B at the model level (
Comparison of Structural Relationships for Two Groups
p < 0.05, ** p < 0.010, *** p < 0.001.
Discussion
The objective of this study was to develop and empirically validate a theoretical model of factors that determine the attitudes of the general public toward the adoption of a novel AI-powered weight loss and health management app. Our research model explained 75.5% of the variance in BI. Five of the factors were shown to positively predict user intention to use such an app, whereas three factors had no effect on user intention. In multi-group analysis, education was shown to exert a moderating influence on some of the relationships hypothesized in the model. The present study provides further support for the validity of three constructs of the UTAUT2 model within the context of m-Health apps, which were shown to have pronounced effects on user intention. We also found that PI and NE play essential roles in influencing consumers in the adoption of the proposed AI-powered app. Our results demonstrate that the UTAUT2 model can be tailored for mobile health care apps.
Smartphones are ubiquitous in our daily activities, with the result that many people are accustomed to using their smartphones extensively and in so doing have developed smartphone use habits. 54 Concurrent with the previous hEalth)related studies, 28,29,33 as indicated in Eq. (2), the degree of mastery in using a smartphone (habit) is the factor with the single greatest effect on one's intention to use an AI-powered weight loss and health management app.
Our results clearly indicate that PE could also be used to predict one's intention to use an AI-powered weight loss and health management app, which is consistent with the findings in previous studies in the health care domain. 28,33,35 Many users perceive m-Health apps as more accurate and convenient than conventional paper diaries. 12 m-Health apps can also be used to overcome the inherent limitations of paper-based behavior tracking, such as low adherence and recall bias. 17 Users who perceive the benefits of utilizing an AI-powered weight loss and health management app to monitor the health status, manage the health conditions, and keep the body healthy are more likely to express an intention to use such app.
PI was shown to serve as a critical determinant of one's intention to use an AI-powered weight loss and health management app. Our results are consistent with the findings in previous research within the context of mobile communications. 38,39,42 As shown in Table 5, the relationship between PI and BI was stronger among those with a master's degree or higher. This means that among the more highly educated individuals, those with strong PI are more likely than their conservative counterparts to adopt an AI-powered weight loss and health management app in their daily lives. We also identified that PI can have an indirect effect on intention via PE. These results are consistent with findings in previous studies on technology adoption. 42,44 Individuals who hold a bachelor's degree or below and value innovation are more likely to perceive the benefits of using an AI-powered weight loss and health management app to attain their goals and are more likely to adopt such measures. Nonetheless, this indirect effect was not particularly strong.
We found that NE plays an important role in influencing users in the adoption of an AI-powered weight loss and health management app. These results are consistent with findings in previous studies in the context of mobile communication. 45,46 Mobile health care technologies exhibit strong NE, 47 which means that the value of an app tends to increase with the number of people who use it. In this study, the respondents reported that the number of app users is an indication of its quality. They also expressed a belief that popular apps are more likely to undergo further developments to improve functionality over time.
SI was found not to have a significant direct effect on one's intention to use an AI-powered weight loss and health management app. These results are consistent with findings in previous research on consumer behavior. 28,38,44 In this study, respondents holding a master's degree or higher appeared to rely less on the opinions and suggestions of others in forming an intention to use an m-Health app. Furthermore, our findings pertaining to individuals with a bachelor's degree or below are in line with previous studies reporting that SI influences intention indirectly through PE. 38,44 This type of influence is indicative of internalization through user beliefs. 38,43 Nonetheless, the weak indirect effect is indicative that SI is somewhat limited in its applicability to predicting user intentions.
EE was shown not to have a significant effect on user intentions to use an AI-powered weight loss and health management app. These results are consistent with findings in previous studies dealing specifically with health apps. 22,28 In this study, the fact that effort expectancy has a nonsignificant effect could be explained by recent advances in the design of user interfaces (UIs) for smart mobile devices, particularly in terms of usability. It is very likely that the respondents have come to expect a highly intuitive UI, which would make it easy for them to become skillful at using such an AI-powered health app.
HM was shown to be a nonsignificant predictor of one's intention to use an AI-powered weight loss and health management app. These results are consistent with findings in previous studies focusing on m-Health apps. 33,35 This result is likely due to the fact that most of the respondents were >21 years of age and well educated. It is reasonable to posit that individuals with experience using similar apps would be concerned with functionality and usefulness over its entertainment value.
FC were shown to be a nonsignificant predictor of one's intention to use an AI-powered weight loss and health management app. These results are consistent with findings in previous studies focusing specifically on health-related apps. 28,40 This may be explained by the abundant experience of the respondents in using smartphones, that is, they have already overcome most of the issues that would undermine their willingness to adopt this kind of technology.
Limitations and Future Directions
This study has a number of limitations, which should be considered when interpreting the results. First, the online data collected in this study focused on adults (aged ≥21 years), most of whom had abundant experience in using smartphones, and more than 57% of whom held a master's degree or higher. Thus, our findings are not necessarily applicable to the general population. Future studies could use other survey platforms to recruit participants of greater diversity to enhance the validity and generalizability of the findings. Second, this study employs cross-sectional analysis of the intention to use our proposed app; however, the actual usage was not measured. Future studies could track participants who actually use our AI-powered weight loss health management app for a defined period of time. It might also be possible to perform longitudinal analysis to assess the effects of BI on actual usage behavior. Third, the conclusions drawn from our study are applicable only to our proposed AI-powered app. However, numerous other factors could influence one's attitude concerning the use of other m-Health apps (e.g., body mass index and health condition), and future studies could address the effects of those factors on the BI to adopt general m-Health apps.
Theoretical Contributions
The validated model in this study provides empirical evidence that the inclusion of NE and PI in the UTAUT2 framework could increase the predictive ability of the model to 75.5%; in other words, the proposed scheme outperformed the other UTAUT2-based studies in the health care domain. 28,29 We also demonstrated that the influence of PI and NE on user intentions far exceed all the independent variables in the original UTAUT2 model, except for habit. Moreover, our results are applicable in the theoretical assessment of other fields.
Practical Implications
The rapid emergence of m-Health apps underlines the importance of identifying the factors that affect the intentions of potential users to adopt m-Health apps. It is crucial that app developers and practitioners have a clear idea of user motivations in the design and implementation of m-Health apps aimed at enhancing adoption. First, habit was identified as the factor with the most pronounced influence on user intentions. This is an important takeaway message for app developers. Developers should adopt the popular functions from proven health-related apps in the development of novel m-Health apps. The inclusion of functions with which consumers are already familiar with could greatly facilitate the development of habits when using m-Health apps aimed at managing health-related behaviors. Second, PI exerts significant effects on user intentions (particularly in the realm of IT). Thus, m-Health apps should incorporate the latest (innovative) technologies, such as medical chatbots, deep learning, and blockchain in the development of m-Health apps. This could help to enhance competitiveness and promote the adoption of m-Health apps by early adopters. Finally, the size of an installed base can have a considerable effect on the adoption of new technologies. Smartphone users would be more willing to adopt m-Health apps that have a large installed base; therefore, practitioners must coordinate promotional efforts (e.g., cost-per-install campaign) with the aim of exceeding the critical mass in the number of m-Health app downloads as quickly as possible.
Footnotes
Disclosure Statement
No competing financial interests exist.
Funding Information
No funding was received for this article.
