I fast on antipsychotics and mood stabilizers. I have the most challenge if a dose is changed but that wears off. Night time is what would usually get me too. I know it’s not the same but might have a similar impact. Antipsychotics are notorious for appetite issues.
I take the generic form of lexapro (called cipralex I no Canada) and have not had any issues with taking it fasted nor have I noticed it has increased my appetite. My doctor told me in their opinion many of the studies linking ssris to weight gain still have variable calories so they are not convinced that the connection is strong as it is not necessarily a causal link.
I’m on Escitalopram (10mg/day) and haven’t had any issues with fasting. I only do 24-hour fasts two times a week, though, and on the remaining days try to stick to a 16:8 schedule.
I should add that I haven’t gained weight from taking SSRIs.
Personally, I’d be careful with respect to longer fasts - I’d probably ask my doctor whether she sees any potential issues.