Researchers in Indonesia created a mobile app called “Teen ’n Fit” to help teenage girls monitor their nutrition, exercise, and iron supplement intake. Before releasing it to the public, they tested whether the app was easy to use by having 64 girls aged 15-18 try it out and answer questions about their experience. The good news: the app scored very high on usability, meaning it was simple and intuitive to navigate. Most girls had never used health apps before, but those who had used similar apps found this one even easier to use. The study shows the app has real potential to help teens make healthier choices, though researchers still need to test whether it actually improves health outcomes over time.

The Quick Take

  • What they studied: How easy and user-friendly is a new health app designed for teenage girls to use?
  • Who participated: 64 girls between ages 15-18 from a public high school in Depok, Indonesia. Most had never used a health app before.
  • Key finding: The app received a strong usability score of 6.0 out of 7, with nearly 80% of participants finding it easy to use despite having no prior experience with health apps.
  • What it means for you: If you’re a teenage girl interested in tracking your nutrition and exercise, this app appears to be designed with you in mind and should be straightforward to use. However, this study only tested whether the app is easy to use—not whether it actually helps you get healthier, which would require additional research.

The Research Details

This was a usability study, which is like a test drive for an app before it launches to the public. Researchers recruited 64 teenage girls from one high school in Indonesia and asked them to use the Teen ’n Fit app while completing specific tasks, such as logging their meals or checking their activity level. After using the app, each girl filled out a detailed questionnaire asking about her experience—things like whether buttons were easy to find, whether instructions were clear, and whether the app felt helpful. The researchers used a modified version of a standard questionnaire that’s been proven reliable for testing health apps. They also looked at whether girls’ prior experience with health apps affected how they rated the new app.

Before a new health app is released to thousands of users, it’s crucial to make sure it actually works well and doesn’t frustrate people. If an app is confusing or difficult to navigate, people won’t use it, no matter how good the health advice is. This type of testing—called usability testing—catches problems early and helps developers make improvements before the official launch. It’s like testing a new video game with a small group before selling it in stores.

The study used a reliable questionnaire (Cronbach’s alpha = 0.945, which means the questions consistently measured what they were supposed to measure). The sample size of 64 participants is reasonable for this type of preliminary testing. However, all participants came from one school in one city in Indonesia, so the results may not apply to girls in other countries or different settings. The study only measured whether the app was easy to use—it didn’t test whether using the app actually led to better nutrition or health outcomes.

What the Results Show

The Teen ’n Fit app scored 6.0 out of 7 for usability, which is considered very strong. This means the app was intuitive, easy to navigate, and didn’t confuse most users. Remarkably, nearly 80% of the girls who tested the app had never used a health app before, yet they still found it user-friendly. This suggests the app was designed with beginners in mind. Girls who had occasionally used other health apps in the past gave the app an even higher usability score than those with no prior experience (p = 0.046, meaning this difference was statistically significant and unlikely to be due to chance). This pattern makes sense: people with some experience using apps tend to appreciate good design more readily.

The modified questionnaire used in the study proved to be highly reliable, meaning it consistently measured usability in a dependable way. This is important because it validates the tool for future testing of similar apps. The study also revealed that the app successfully incorporated multiple features that girls found useful: the ability to assess nutritional status, track physical activity, monitor eating behavior, receive nutrition education, and get reminders about iron and folic acid supplements. The fact that all these features worked smoothly together without overwhelming users is noteworthy.

This study builds on existing research showing that mobile health apps can be effective tools for promoting healthy behaviors in young people. Previous studies have shown that apps designed specifically for teenagers tend to have higher engagement rates than generic health apps. The Teen ’n Fit app appears to follow best practices in app design by being simple, focused, and tailored to the specific needs of Indonesian adolescent girls (including culturally relevant nutrition information and attention to iron deficiency, which is a common health concern in this population).

The study only tested whether the app was easy to use—it didn’t measure whether using the app actually improved girls’ health, nutrition, or physical activity levels. All participants came from one high school in one Indonesian city, so results may not apply to girls in rural areas, different countries, or different age groups. The study didn’t follow girls over time to see if they continued using the app or if their engagement changed. Additionally, knowing they were being tested might have made girls more careful and positive in their responses than they would be in real-world use.

The Bottom Line

If you’re a teenage girl interested in tracking your nutrition and physical activity, the Teen ’n Fit app appears to be well-designed and easy to use (moderate to high confidence). The app may be particularly helpful if you’re new to health apps, as it doesn’t require prior technical experience. However, remember that this study only confirmed the app is user-friendly—it hasn’t yet proven that using it will actually improve your health. Before making major health decisions based on the app, discuss your goals with a parent, school nurse, or healthcare provider (high confidence in this recommendation).

Teenage girls aged 15-18, particularly those in Indonesia or similar settings, should find this app useful. Parents and school health educators may also appreciate having a tool to encourage healthy habits. Healthcare providers working with adolescents may want to recommend this app as a supplementary tool. However, girls with eating disorders or disordered eating patterns should consult with a healthcare provider before using any nutrition-tracking app. The app was designed for generally healthy adolescents, not for medical treatment of health conditions.

This study only tested the app once, so we don’t know how long it takes to see benefits. Typically, building new habits takes 2-4 weeks of consistent use. You might notice increased awareness of your eating and activity patterns within the first week or two, but meaningful changes in nutrition or fitness usually take several weeks to months of consistent tracking and behavior change.

Want to Apply This Research?

  • Use the app to log your meals and snacks daily for one week, then review the nutrition summary to identify one eating pattern you’d like to change. Track this specific change (such as adding one extra serving of vegetables daily or reducing sugary drinks) for the following two weeks and note any differences you observe.
  • Set a daily reminder in the app to log your meals at the same time each day (such as after dinner). Start with just tracking breakfast and lunch for the first week, then add dinner and snacks once the habit feels automatic. This gradual approach is more sustainable than trying to track everything at once.
  • Check your activity and nutrition summaries weekly rather than daily to avoid becoming discouraged by day-to-day fluctuations. Take a screenshot of your weekly summary every two weeks to visually track progress over time. After one month of consistent use, review your overall patterns and identify one new healthy behavior to focus on for the next month.

This study tested whether the Teen ’n Fit app is easy to use, but it did not test whether using the app actually improves health outcomes. The findings apply specifically to teenage girls in Indonesia and may not generalize to other populations. This research is not a substitute for professional medical advice. Before making significant changes to your diet or exercise routine, consult with a healthcare provider, school nurse, or registered dietitian. If you have concerns about your nutrition, weight, or eating habits, speak with a trusted adult or healthcare professional. This app should be used as a supplementary tool alongside, not instead of, guidance from qualified health professionals.