As mentioned, they can go off feed if you go too large. Here is a real life example:
Snake A and B are the same size
Snake A eats a 150g rat, goes off feed for 2 months and consumes 150g in 2 months
Snake B eats a 75g rat every week for 2 months and consumes 600g in 2 months
Snake A is no longer the same size as snake B