potentially unknown effects on the gut microbiome etc... do you use artificial sweeteners etc..?
I don't see the advantage tbh...not at the moment at least, beyond maybe doing it for a short period of time for something specific like weight loss - even then you could just go into calorie deficit in a regular, otherwise balanced diet anyway.
I'm not saying it is definitely a bad thing I'm just not sure why people do it rather than just eating healthily in the first place? It just seems like a bit of a fad that is all.