This study measured various demographic variables. Standard survey questions used in the previous study were used to collect demographic measures at baseline [27]. This included age, sex, marital status, educational achievement, and whether participants had ever used a dietary smartphone app outside of the research. Participants were asked to self-report their height and weight, from which BMI was calculated using the following formula [44]: weight (kg) / (height [m])².

The quantitative outcomes of this study were DASH diet adherence and participants’ self-efficacy, which were assessed at baseline and at the end of the intervention.

To evaluate the change in DASH diet adherence, macro- and micronutrient intakes were assessed using a 3-day food record before and after the intervention. Nutritics dietary analysis software (version 5.95) was used to analyze reported intake to determine the changes in adherence to the DASH diet [45]. Participants were asked via email to complete a 3-day food record before week 1 and at the end of week 8. We calculated a nutrition-based DASH index score, similar to the DASH index score formulated by Mellen et al [46]. The score for DASH diet adherence was computed based on 9 target nutrients: total fat, saturated fat, protein, fiber, magnesium, calcium, sodium, potassium, and cholesterol. A value of 1 was assigned to participants who met the DASH target for a nutrient, 0.5 if they met the intermediate target, and 0 if neither target was met. Thus, the range of scores was 0 to 9, with higher scores indicating greater adherence, while a score of 9 represented full adherence [47].

To measure DASH diet self-efficacy, this study adopted the 6-item diet self-efficacy scale with participants rating each item on a 5-point Likert scale ranging from 1=not confident at all to 5=completely confident. Total scores for the scale range from 6 to 30, with a higher score indicating greater self-efficacy.

SPSS software (version 26.0; IBM Corp) was used for all statistical analyses. Descriptive statistics were used to describe all variables; frequency and mean with SD were reported.

Participant interviews were digitally recorded, transcribed verbatim in their language (Arabic), and coded using the MAXQDA qualitative analysis software (version 12.0; VERBI GmbH) [56]. Although the participants could read and speak English, the interviews were conducted in Arabic because people feel more confident speaking their first language. A thematic framework analysis was performed to identify the key themes within the data [57,58]. The thematic framework was developed through a combination of inductive and deductive approaches. A framework analysis was selected for its effectiveness as a tool for qualitative content analysis. This method provides a systematic approach to organizing and mapping data [58]. It is valuable for analyzing interview data, comparing themes within and between cases, and managing large datasets by offering a structured data summary [58]. Inductive methods involved identifying and categorizing emerging ideas into preliminary themes, while deductive methods mapped these themes based on social cognitive theory [21]. Two researchers (GA and JZA) independently analyzed and explored the transcript data, taking notes on preexisting and emerging themes. These notes were used to create a coding framework applied to the transcript data within MAXQDA. The data within each theme were then thoroughly examined and summarized, including differences between participants, to create summaries of each theme and identify similarities and differences between themes. After discussions with EAW and MSH regarding the final analysis stage results, GA implemented some adjustments. In this study, quantitative and qualitative data were analyzed separately [59]. In the final interpretation of the results, the quantitative data complemented the qualitative data [59,60]; for example, in the case of missing data, interviews may show why one point of measurement has more missing data than another. This study used an integration matrix (Multimedia Appendix 3) to compare data obtained from different methods.

The one-on-one interviews were conducted with 9 (75%) of the 12 participants who completed the study. The data analysis revealed four overarching descriptive themes concerning the Noom app’s use over the previous 8 weeks: (1) acceptance, (2) app usability, (3) technical issues, and (4) suggestions for improvement. The thematic framework analysis is presented in Multimedia Appendix 4.

The Noom app was generally well accepted and liked among the participants who completed the study. Most of the participants generally found the Noom app easy to use, and as a result of consistently tracking their behavior, most were able to re-evaluate their dietary choices and break old habits (as shown in the quantitative data, of the 12 participants, 8 (67%) had improved their DASH diet scores):

Most of the participants experienced positive changes in their behavior due to self-monitoring and receiving regular feedback through the app. The app color coded positive and negative energy balances—green for positive, yellow for neutral, and orange for negative—which helped them become more aware of their dietary habits and encouraged them to reflect on their behaviors. Furthermore, the feedback allowed them to make improvements, eventually increasing their self-efficacy and DASH score, as evidenced by the quantitative data:

Many of the female participants were able to positively impact their children’s eating habits by incorporating more fruits and vegetables into their diets, serving healthy snacks, and having dinner earlier (one of the participants even suggested that her friend try using the Noom app):

There were mixed opinions regarding the reminders (sent through the app) for logging food and reading articles. Some found these messages helpful and promptly acted on them, while others ignored them but still appreciated receiving them because they helped them log the meals missing from their record. However, some of the participants did not find the reminders helpful, and they disabled the notifications because they received them at inconvenient times and found them annoying:

Most of the participants reported that effective app use required self-motivation to change behaviors. They were self-motivated to continue using the app due to positive outcomes, health concerns, and daily goals such as calorie limits. Moreover, some reported that the app provided daily motivational messages that encouraged them to continue using it:

Participants had differing opinions about using the app when they were busy or on holiday. The app benefited some because it allowed them to manage their food intake during the holidays, specifically during Eid ul-Adha (Festival of Sacrifice), while others did not use the app during this time (this reason could explain the differences in app engagement):

Participants felt that they benefited both psychologically and behaviorally from the app’s educational component. Most of the participants felt that the Noom app provided them with information to increase their confidence in selecting healthier food, monitor their dietary intake, and incentivize eating healthy food:

However, all participants expressed their dissatisfaction with some of the Noom app’s suggestions and language. Some of the app’s recommendations cater more to Westerners and do not consider Arab and Muslim cultural differences; for instance, some of the users found it odd that the app suggested limiting alcohol consumption to only 1 serving. Furthermore, the app incorporates American slang (eg, “listen to your gut,” “take the plunge,” and “veggies”), which can be confusing for some users who are not familiar with the language:

Most of the participants reported that the Noom database contained a variety of foods and was easy to use, convenient, and valuable. However, participants reported difficulties in identifying certain foods due to a lack of local options on the app, such as local restaurant foods and traditional cuisine. Mixed dishes, such as kabsah (a traditional Saudi Arabian dish with rice and meat), and homemade foods also posed challenges for some of the participants. Regarding the option for users to add their foods to the database, only a few of the participants found this helpful. Some of the users expressed concerns about the accuracy of food information in the database after adding their foods:

Some of the participants reported that they were unable to incorporate the app into their daily routine quickly, which was supported by their SUS score for the question “I would imagine that most people would learn to use the Noom app very quickly”:

Participants reported technical errors, including the app frequently freezing or responding slowly; this happened to 4 (44%) of the 9 participants. They solved this issue by uninstalling and reinstalling the app:

When participants encountered technical problems, they generally did not contact the primary researcher. These problems were usually only discovered during the interviews. Some of the participants hesitated to trouble the researchers with technical issues stemming from their slow internet connections. By contrast, a few of the participants preferred to contact the Noom app support team to address the technical problems because they believed that the support staff were accountable for such matters:

I contacted Noomapp support about this issue, and they replied they were aware of the issue and were working to resolve it. [Participant 5, male, aged 41 years, master’s degree]

There were some suggestions to improve the Noom app. These suggestions included developing an Arabic version, reviewing its content, and deleting any recommendations unsuitable for Arab and Muslim populations:

Furthermore, participants believed that adding some traditional Saudi Arabian and Arab cuisine would be a useful addition because people from all backgrounds and ages would benefit from this, making the app more appealing to users from these regions. Participants also suggested that it should have offline functionality and that subscription prices should be reduced. These changes would improve the app’s accessibility and usefulness for all users:

I want an Arabic version of the Noomapplication that is in line with the Arab and Middle Eastern cultures, also its price is expensive. [Participant 4, male, aged 35 years, bachelor’s degree]

A final suggestion was to find a method to make logging food easier (although the Noom app a barcode scanner for identifying food, it seems unable to recognize some of the local Saudi Arabian products):

This study examined the feasibility and acceptability of using the Noom app to assist people with high blood pressure to improve their dietary behaviors. After an 8-week intervention, this study found it feasible and acceptable to use a commercially available app to support DASH diet self-management among people with high blood pressure in Saudi Arabia. Moreover, there was a positive trend toward an increase in DASH scores and self-efficacy, but these results were not statistically significant.

The study recruited 14 people with high blood pressure. The participants who took part in the interview (9/14, 64%) expressed positive opinions about the intervention. Many of the participants reported significant benefits from the intervention in terms of their motivation to change their dietary behavior and their psychological or physical well-being. Most of the participants found the Noom app easy to use, and most had no difficulties integrating it into their daily routines.

However, of the 14 participants, 2 (14%) withdrew from the study; furthermore, of the 12 participants who completed the study, 3 (25%) did not take part in the interview. Some found the app overwhelming when monitoring their diet. This feedback was based on participants’ reasons for withdrawal. The findings indicate that dietary smartphone apps may be more effective for individuals with high motivation and willpower. Consequently, an intervention based on a dietary smartphone app may not be beneficial for those who are less motivated and less willing. Similarly, a previous study assessed the use of the MyFitnessPal app for weight loss [61]. It concluded that clinicians may not necessarily recommend the app to every patient who is overweight and has a smartphone unless they are motivated to lose weight and track their calorie intake. For these patients, the app could be a helpful tool [61]. However, our study’s findings should be interpreted cautiously due to the small sample size and short study period.

Dietary smartphone apps have been found to be a promising intervention for supporting DASH diet self-management [30]. Our study found that the Noom smartphone app seemed to improve adherence to the DASH diet at 8 weeks. These findings are consistent with a recent randomized controlled trial conducted in Iran, which revealed that a smartphone app improved adherence to the DASH diet plan [62], highlighted by a clinically meaningful difference in DASH indexes between the two groups at the end of the study. Nonetheless, the results did not reach statistical significance. Most of the participants in our study suggested that personalized feedback, motivational reminders, and knowledge were essential to increase participants’ DASH adherence and app engagement. This aligns with the principles of behavior change theories, which emphasize the importance of goal setting, feedback, and knowledge for successful self-management and behavioral control [63,64].

Most of the participants (8/13, 62%) in this 4-week study tracked their diet for 3 to 5 days a week. During the second month, the number of days the participants used the app generally increased, while the time spent per day on it decreased. The results of this study contradict those of the study by Laing et al [61], who found that the use of MyFitnessPal, a popular app for diet tracking, decreased considerably after the first month [61]. In our study, it is possible that the motivational reminders and feedback provided by Noom, the need to log meals missing from the record, additional meals (the meals that are not found in the food database), and saving favorite meals encouraged the participants to maintain a higher frequency of engagement. In addition, a possible explanation for the decrease in time spent per day engaging with the app is its time-saving features, such as the option to save favorite meals and foods [65]. Ziesemer et al [66] reported that fixed daily reminders and logging meals missing from the record could increase the awareness and number of logged eating events in the short term. However, the long-term effects of fixed reminders remain unknown. Moreover, most of the participants acknowledged that perceived missed events were likelier to be snacks than main meals because they logged their food at the end of the day, forgot having had snacks, were busy, or had no Wi-Fi access. Similarly, the study by Ziesemer et al [66] found that snacks were more likely to go unrecorded. The most common reasons were obstacles related to devices (eg, the absence of a device at hand), multitasking, or situational barriers [66]. Further research is needed to identify events that are likelier to go unrecorded and to determine the reasons for such omissions.

Moreover, studies show that individuals who practice self-monitoring tend to experience greater success in changing their health behaviors [20,67]. The Noom app includes information on calorie balance, which helped participants confidently estimate the calorie content of foods. Furthermore, participants’ feelings toward certain types of foods were influenced by Noom. This led to heightened awareness among the participants, increasing their consumption of fruits and vegetables and decreasing their consumption of unhealthy snacks, fast food, soft drinks, and high-fat foods such as red meat. Some of the participants also found the app helpful in regulating their food intake. Engaging in self-monitoring behavior can help users gain knowledge about which foods are beneficial or detrimental to their diet, ultimately improving their ability to achieve their goals [20].

In addition, after using the Noom app, some of the mothers among the participants decided to increase the amount of fruits and vegetables they served their children. This positive influence of the Noom app aligns with the results of a systematic review [68] highlighting the effectiveness of digital interventions in promoting nutrition among parents and improving outcomes for both parents and children.

Another factor that positively influenced the acceptance of the Noom app was the positive feedback and motivational information provided in the educational information. After using the app, participants reported feeling more motivated and capable of improving their dietary habits. They also experienced an increase in their ability to set and achieve dietary goals. Bozorgi et al [69] demonstrated that using a mobile app–based education intervention improved adherence to low-fat and low-salt diets among patients with high blood pressure. Participants’ self-efficacy level was also increased during our study. Our findings are consistent with prior research showing that diet apps can improve self-efficacy or improve individuals’ belief that they can engage in healthy eating behaviors [70]. The findings of our study are theoretically supported by social change theory, which argues that individuals’ confidence that they can consume healthy food daily, despite challenges, is often a major determinant of their ability to adhere to a healthy diet [21]. From a psychological perspective, positive or negative consequences for the individual’s health are essential factors influencing behavior [71]. Therefore, when developing nutrition apps, it is crucial to avoid fostering feelings of shame by presenting information in a positive manner.

Although the Noom app was considered an acceptable tool, some of its educational content proved unsuitable for individuals with elevated blood pressure in Saudi Arabia. Participants refused to adopt some of the app’s suggestions that did not align with their cultural beliefs; for instance, the app recommended having a nightcap before sleep, which was not well received. Empirical studies have shown that health and diet promotion initiatives that consider culture, ethnicity, and language are more effective in motivating individuals to adopt healthy behaviors [72]. Therefore, it is crucial that personalized nutrition advice and messaging are provided, along with tailored recommendations for affordable and accessible meals and recipes that align with an individual’s daily diet [73]. As König et al [71] pointed out, besides technological factors, the characteristics of a potential user, the interaction between the user and the technology, and the social environment also play a role in the use of nutrition apps. Alzahrani et al [74] developed an app called Sehhaty Wa Daghty (Arabic for “health and blood pressure”) to cater to the cultural and social norms of Saudi Arabia, the motivational needs of male and female Saudi Arabian citizens, and their hypertension management needs. This app allows for easy tracking of blood pressure, physical activity, and a healthy diet, and it provides reminders for medication intake and water consumption. Most of the participants found the Sehhaty Wa Daghty app easy to use and acceptable [74]. There are notable differences between this intervention and ours. The research team developed an app for their study [74] rather than choosing one that was commercially available. Consequently, the app underwent prototype testing, and the researchers had to consider many user design aspects more appropriate for the Saudi Arabian population. Nonetheless, it is worth noting that the use of the Sehhaty Wa Daghty app was limited to the study population, while the Noom app is accessible to the general public. Alzahrani et al [74] discuss valuable insights on the development of a smartphone app for self-management of hypertension among Saudi Arabian patients. They emphasize the significance of considering cultural and social norms when creating digital health programs in Saudi Arabia. Our findings add to this evidence and suggest that commercial dietary smartphone apps have the potential to be used effectively among the Saudi Arabian population.

The accuracy of the food database is crucial to the Noom app’s user acceptance. Although the app offers a comprehensive food database—including data from government sources, such as the US Department of Agriculture’s food database; international restaurant chains; and some Arab cuisines—it lacks many traditional Saudi Arabian cuisines, which affects food tracking. Many Saudi Arabian participants reported that food data entry was complex due to the need to estimate portion sizes as well as calorie, fat, and protein content. They were also concerned about the food database’s accuracy and reliability. A previous systematic review has demonstrated that issues related to the usability of food intake tracking can affect users’ willingness to record their food intake [71]. The systematic review also emphasized that nutrition apps that allow users to enter data are prone to human error; consequently, nutritional values are likely incorrect, and their sources could be uncertain [71]. Therefore, using simpler input methods, such as using household items to indicate portion sizes or photo-based food recording, can alleviate the burden on users [71]. To increase users’ trust, it is crucial to create opportunities to enhance transparency regarding food data sources if human error cannot be avoided completely [71].

The Noom app worked well most of the time. Nevertheless, the most challenging technical issues were freezing and slow response times. The support team assured users that they were working on a solution. These technical issues, as well as app malfunctions, can lead to user disengagement [71]. Therefore, these issues must be resolved before conducting future studies to ensure that the app can be widely adopted.

Most of the participants followed the DASH diet but could not fully adhere to it. Steinberg et al [47] found that lower-intensity approaches that focused solely on dietary behavior had only a slight impact on adherence to the DASH diet. Moreover, it has been challenging to achieve complete adherence even in DASH trials that have included intensive behavioral interventions [75]. In the PREMIER trial [76,77], a comprehensive and multicomponent behavioral intervention was used to improve the adoption of the DASH diet. The intervention consisted of group meetings and frequent face-to-face counseling sessions with a registered dietitian. The intervention included sodium reduction, increased physical activity, and weight loss [76]. Although the intervention effectively improved DASH diet adherence, it did not lead to full adoption. Although the DASH recommendations are comprehensive, their full adoption may be challenging when the focus is on multiple behaviors simultaneously. A previous study indicated that although full adherence was optimal, partial adherence to the DASH diet could lower blood pressure [47].