What drinks are ok with the No Grain Diet?

I just spent almost 20minutes googling the internet to find out what "drinks" are allowed on the no grain diet? To me, this should be covered in first chapter but I can't find anything in the Mercola book or another one I have (I have not read them entirely but atleast as far as I can see).

We drink more than we eat and for me, starting this diet I needed help with this question as I drink alot of diet coke and do have a cup of strong coffee in morning (1 cup).

Is this allowed? (please say yes)?

That is the only thing I can see hard on this diet is if I cant have my diet cokes or one cup of coffee in morning?

Does anyone know?