I’m on a higher dosage of antipsychotics and I have done some intermittent fasting and have done ok on it. I do keto too which I think helps with the hunger. Not sure about the antipsychotic slowing down metabolism. I recommend talking to your doctor next time you see him/her. Good luck with your fasting!
I guess it could depend on the med, but i was on zyprexa for almost 2 years. It gave me prediabetes and cholesterolemia, but it also documented to be a side effect. I ended up having strokes and could barely eat for 4 months and while i did lose some weight, it wasnt much. I stopped the zyprexa after strokes, but it wasnt until almost 2 years later after a few months of IF and healthy Keto amd exercise that i started dropping weight. My experience anyway.