I've said it before, your snake doesn't need to be fat to be happy! Snakes grow slowly, and our captive ones are going to have more fat deposits than ones in the wild regardless. [from limited exercise and fatter meals]

So, if they aren't skinny to the point you need to see a Vet, don't worry. Let other people stuff their snakes like scaly sausages, and feed yours appropriately sized meals just like everyone here said.