Table 2 Usability problem of the beta-version of myfood24 and adolescents’ comments and recommendation

My profile (age, sex and general instruction)

• Missing the list of age and counties from drop down menu.

• ^aProvide missing action (age and list of counties

• All users read the instructions and find it easy to understand

Make a list function (area where users can report all food consumed)

• Not clear how to use it, users typed food name with its portion or brand so nothing comes after searching

• ^aAdd “mouse hover” to help in how to use it

• When users learnt how to use it, they found it useful as a reference point to remember what they ate

Food search bar (select food items from the search bar, filter the findings using category or brand)

• The search function is not reacting enough to find misspelled words

• ^aAdd spell checker and auto filer in the food search

• Spaces between words can be an obstacle when searching (e.g. Kit Kat and Kitkat)

• ^aAdd more synonyms for food name which can be written in different way

• Uncertainty in the results of food searching.

• ^aPresent the results in alphabetical order

• Brands and generic foods are mixed up, which hampers finding the right food (Fig. 2)

• ^aRe-programme the filtering system to be more effective

• Some users found the “search bar” superior to “make a list” function

Food portion-size (select one of three options: Standard pack size or select from food photos or enter exact g/ml)

• Not clear how to do the action correctly

• ^aMaking a tutorial video regarding how to select portion size.

• Average portion presented with photo portion size, so users were confused about which one to choose (Fig. 2)

• Label food photos with grams to help adolescents realize the average portion in relation to other photos. Users said that may help them make the right decision

• Uncertainty of some food portions, such as some drinks has one option while others have three options

• ^aDifferentiate visually between average and food photos by writing ‘OR’ or present them in different levels

• Free entering for ‘total gram’ does not work with some foods

• Entering foods portion-size becomes easy in the second use

Pop-up for missed items (Have you missed any of these items? Margarine, butter ..?)

• It seems unnecessary for certain foods and caused a bit of a hassle

• ^aIt may be better to appear once after each meal and at the end of the diary

• It would be easier if participants could click on the items in the prompt to take them straight to the food search bar

Recipe builder (create new recipe and select the portion from exist recipe)

• After submitting the recipe, there is no visual sign to find the saved recipe

• ^aMake enough visual sign (e.g. make the icon flashy)

• Not clear how to enter portion consumed, how to add it to the diary

• Need information in help option or in the instruction in “My profile”

Meal slot (Breakfast, Lunch, Evening, Snack, Drink)

• Having ‘drinks’ as an option confused the users ( they thought all drinks should be in this section (Fig. 2))

• Better to remove it, or mention when to use it in help section

• Not easy to move (swap) selected foods between meal slots

• It would be easier to drag and drop food to the right meal slot

Submission page (Prompts to check entries, answer additional questions: supplements intake and if their food record represent usual intake

• There were three submission buttons on the page which confused users about which one to press

• ^aKeep only one submission and make it visible for users

• There is no enough visual sign for the additional questions

• ^aThe question needs to be in different colour or bold

• Some users did not understand what was meant by ‘supplements’

• ^aAdd simple definition between brackets

Nutrient summary

• Bugs in the nutrients summary figures

• ^afixed bugs

• Users like to compare their intake with the recommendation