Need your help and suggestions

Hello there hope everyone are doing well please I need your help and suggestions.
I plan to make a website (non English website) about healthy recipes and I want to integrate the BMI calculator in it.

I want when a user calculate his BMI get automatically monthly plan meals based on his preference of foods I don't know how to do that. I need help sorry for my bad English

To make things clear more I need to make same like this website(https://www.carbmanager.com/) please I appreciate any help and suggestions.