From your 'My Hub' page (please see below)
If you go to the 'Menu' icon in the top right...
then select 'Groups' from the options
This will show any groups you have created
Click the 'Nutrition' tab from the 5 options at the top of your page.
And by clicking 'Create Nutrition Group' at the bottom of your screen
You will then be able to create a nutrition group
And once created you can simply select the group to add any nutrition plans.