Planning my first GLP-1 Experiment

Hey all I’m coming at you today and letting y’all know I’m starting my first anecdotal experiment. Looking into Reta for my participant. Only other peptides we’ve experimented with was BPC and TB500. Participant is 245lbs (111kg). Is there a recommended dosage chart or path we can follow for the entirety of the experiment. The goal is to achieve 180 lbs (81kg) - 200lbs (90kg)

Edit: Participant has a lot of mass they want to maintain from many years of strength training and powerlifting. Besides keeping protein intake really high, what other methods can they do to help skeletal muscle retention?