Fasting is not conducive to muscle gain. To build muscle you actually need to eat in a caloric surplus. Nothing wrong with fasting as a lifestyle, but don’t do heavy lifting on days you don’t eat or do OMAD.
Skip fasting if your looking to add muscle mass. Eat every 2-3 hours you’re awake. You must eat a high quality meal every time you eat. Lift heavy weight to failure.
Example meal:
boneless skinless chicken breast
broccoli
handffull of walnuts
You can also try SARMS for adding muscle mass. I got good results with https://paradigmpeptides.com/
Do basically OMAD, but rather than seeing it as a meal I see it as a window, an eating window. Plan out you 2500-3000-3500 calories during that time. Also, workout and then eat, not eat then workout. If you’re 175lbs a goal or 200g of protein is pretty good. Healthy carbs are gonna help as well.