In point of fact, I really do not have an idea about the exact Estimated time of arrival of this project. Being a senior iOS developer I am a good graphics designer also, therefore, I have a suggestion, you may consider if you like, first I will create a mock up, then clarify this to you and then will provide the ETA for this project.
After read your proposal what I realized is that basically You want to put an AI-assisted prediction of a weight trajectory changes in real-time through this app as you want to make lifestyle changes and exercise. This is revolutionary as it helps motivate people on their progress and lets them know if they are making a difference.
Specification:
Will the app have only 4 options for now? Such as Why Us, How, Contact and Plans. Does these segments(Why Us, How) will show up the static text like your doc?
If yes, then don't you think that your app does violate the "Not enough lasting value" guidelines as you wants "Why Us and How will show up the static text in app without any user being specified". In this way, your app do not keep sufficient features as it doesn’t offer much functionality or content, basis on that it may not be approved by the App Store Review.
-There should be a Contact portal in app to provide supports as well as regular consultation via phone/skype, email, whatsapp
-Plans: ok. Please let me know what payment gateway do want in app? or it will be in-app purchase subscriptions with some features in app? pls clarify.