I assure you that significant weight loss will affect gun fit.
I went to the Grand and Cardinal Classic last year and couldn't hit anything. I'd lost about 45 lbs and didn't realize what the problem was.
Since then, I've lost more for a total of 66 lbs, but Keith Heeg, who winters at the Dollar, has kept my gun fitting as I went down. He's not only a AAA shooter and great stock man, but is a great coach and fitter, too.
I'd like to lose another 20 (without cutting off one of my legs) so I know I will have to watch the fit.
I've lost 50lbs so far and it is a real battle to stay on top of my shooting form. I have fallen from AA to A but I am making some headway and hope to be back soon. Some days I have to look to make sure I didn't pick up the wrong gun!!
I agree with Rich I've lost about 40 lbs and am having trouble figuring out why I'm dropping targets,I've adjusted my gun so I don't think it's gun fit cause I will ink 15 or 20 targets in a row and then randomly miss a couple targets clean it's like I have to learn my gun all over again.I never have been a AA shooter more like an A/B but right now I'm shooting more 21's than 24's.Jerry