No diet coke but coffee is okay...

I think it all boils down to preference.

It is best for you to do research on your own and figure out what you think is appropriate.

What I notice is some people will excuse anything as a 'fasts' since they are unable to follow the exact criteria themselves.

My personal view is that anything other then water is not a fast. If people want to drink something other then water they should mention that so others are not deceived. For example people should say "I am liquid fasting X amount of days on A and B fluids..." not "I am water fasting..." and then two weeks later we all find out they did drink coffee or whatever else. It is alot like someone claiming to run a marathon but drove a quarter of the way by taxi.
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