What is the best way to lose fat but gain muscle at the same time?

I’ve been injecting GHK-CU, and wanting to improve my skin for my face. One thing I struggle with is Blackheads on my face. What could I use to treat the blackheads, also I’ve been seeing a trend of Tretinoin on tik tok, I’m curious about it but i don’t want to endure the purging phase. Is there way to bypass the purging phase or is it not even worth using tretinoin?

I’ve been seeing under eye caffeine serum on tik tok, does that stuff actually work?