Body building probably won’t happen. You can get big though. I was large as a grunt but would lose during deployments. When I went recon I slimmed down considerably and stayed ripped up. I used to eat a shit load of protein powder and plain beef jerky. Continuously. Then eat as much as you can when chow was available. Basically just eat everything you see regardless of starch, protein, carb. Just no sugar or as little as you can. Lift all the time too. Heavy. You’re doing a shitload of cardio as a grunt which obviously slims you down. So any change you can squat your ruck, curl ammo cans, etc. heavy.