I am not a massive eater but I do allow myself some subtabcial meals when i am out for epic rides...
I'm not sure what subtabcial means, but it's better not to eat large meals even on long rides. I would say especially, but you know your body better than i do.
I have found that i have gained weight and muscles in my thighs and probably my backside too, but it looks better than the pre-muscle state, so if i go up a size i don't care.

I'd rather have heavier better shaped legs and butt anyday. I have a cousin who has no butt at all. ! I don't think men like that either..