Hi there,
Understood the project in full. I happen to have experience with the nutrition and exercise, as that marked one phase of my life, and I even have my own website with very similar functionality as your requirements are.
On another note, that code is very old and outdated (one of my first personal projects) so I wouldn't be reusing that, instead I would code it from scratch. I would use a PHP framework CodeIgniter for this so we have a nice OOP/MVC code which is easy to expand and maintain.
While I have fully understood what you need, I would be able to provide a more accurate quote if you could provide more details, mainly on 2 features:
1) when you create a training plan, and in the step you add exercises one by one, do you need any formatting in terms of how the end user will see that, or will there just be and option to add a video and a photo, and maybe 2 fields - exerice name (optional) and exercise description
2) about the nutrition plans "user must able to combine/set-up his own plan based on the provided food", do you want it to be, monday, tuesday...sunday, or would you like user to be able to create "personal plan 1", "personal plan 2"..."personal plan n" out of the foods in the plan they have purchased?
These 2 seem to be the complicated parts, rest is pretty clear and I'm able to estimate the time for them.
Regards,
Julijan