Discussion
obesity, weight loss, weight reduction
OBESITY
The results of this app-based multimodal weight loss program showed a statistically significant weight and fat mass loss after 12 weeks and consecutive weight maintenance after 12 weeks of follow-up. Furthermore, it became evident that the extent of weight loss was dependent on the perceived app usability and user acceptance as well as on the duration of app use.The observed weight loss of 2.6% (LOCF) and 3.2% (completers analysis), respectively, within 12 weeks was moderate and comparable to another study in which an app intervention in combination with a smart band to track physical activity resulted in a loss of body weight of 1.97 kg after 3 months [In this study, the app was used for 12 weeks due to a specific regulation in Germany where DiHA are prescribed for a quarter, with the option for an extension. Therefore, the 12-week app intervention period was followed by a voluntary 12-week extension of app use, which did not result in further weight loss, but the reduced body weight was maintained. A period of 12 weeks of app use may be too short to fully exploit the potential effect on body weight, since maximum weight reduction is usually observed after four to six months or even later, depending on the type and modalities of a lifestyle program [To date, the literature on mHealth approaches for the treatment of obesity is heterogeneous, as multiple combinations of app-based interventions with other tools are frequently applied. Usually, the application of a solely app-based lifestyle intervention results in moderate weight loss over 24 months [Despite the moderate weight loss, solely app-based interventions have the advantage of a high scalability because they can be easily provided to the large number of people with obesity. In the German healthcare system, DiHA can be prescribed for people with obesity as the only basic intervention program which is free of charge for patients. Dependent on obesity grade and on obesity-related comorbidities a subgroup of patient needs a more individual and intense clinical care.In terms of app usage and acceptance both groups had similar TAM scores after 12 weeks of intervention. Interestingly, participants of the ADHOC group with a middle or high TAM score showed a significantly greater weight loss compared to participants with a low TAM score indicating that a more positive attitude toward app usability and user acceptance was associated with a greater weight reduction. Therefore, the use of such questionnaires might be helpful for early identification of individuals who would particularly benefit from app use or probably not because of e.g. limited technology acceptance. A systematic review summarized the factors influencing users´ acceptance and use of apps. It shows, that a lack of fundamental motivation to alter the current situation can limit the efficacy and acceptance of even the most-well-designed app [App user adherence, measured here as minutes spent on the app per week decreased over time, which is in line with other studies [Real-world-data provided by a commercial app provider and containing data from 25,706 persons (United Kingdom, Germany, Switzerland) who used an app for prevention and therapy of nutrition-related conditions could identify a relationship between the app components and weight change [A limitation of the study is that it isn’t representative for the population in Germany. In addition, it was conducted as a single-centre study in the Munich region. Compared to other weight loss studies, the gender distribution showed a rather high proportion of men compared to women (35.7% vs. 64.3%). Furthermore, all age groups and the pre-defined BMI range (30.0 to 40.0 kg/m