It might not, however let me also give a few healthier options without aspartame sweetener that aren’t plain water that you might be able to replace it with!
And for full disclosure, I did drink a diet coke pretty much daily on my very first round of hCG. So I have done it and I did lose 27 lbs in 42 days on that round. Later though I did get myself off diet coke entirely.
So it’s not that it won’t be okay but if you’re open to the idea, here’s some other options:
What Else Can I Drink Besides Water on hCG?
Super low cal options for “cheating smarter” on hCG
I hope this helps!