Healthy eating?

Before I've bought my first snake last year, I remember reading about feeding the snake a rodent no larger than the thickest part of its body. But in the wild you could see snakes eat food two or three times thicker than its own body. Like a reticence eating an antelope or anaconda eating a hipo.
My snake is three feet and eats med rats, this leaves a pretty slight bump on him, not HUGE just a slight bump. I've seen ads on Kingsnake.com of two and a half to three footers eat large rats.
Is this healthy eats for the snakes? Or could it be considered pushing it?

If the medium rat leaves a slight bulge in him, it's a good size for him and he doesn't need to be moved onto larger prey. Yes, snakes can eat prey that is considerably larger than they are, but in the wild you have to remember they don't always have regular food sources, so it'd be like you not eating for three days and then stuffing your face with a four-patty hamburger and fries. Sure, you can eat it, but smaller meals more often is easier on the digestive system and seems to keep them from going off of feed much more.