One of the things guinea pigs are really good at it eating. If they can find something to nibble on they will do so.
One of the main reasons guinea pigs are always chewing on food is because their teeth are always growing and therefore they need to chew on things to grind down their teeth to keep them short.
Because of this fact guinea pigs will always be looking for things to chew on to help them with their teeth.
So can guinea pigs overeat at all?
Luckily guinea pigs can control how much they eat and do get full like humans. A piggy will stop eating food and safe regulate themselves when they get full.
Therefore it is still always important to give your piggy access to fresh water, vitamin c pellets and fresh hay to chew on to maintain the length of their teeth.
Additionally it is important to make sure that you guinea pig has plenty of space within their cage to run around and get exercise especially since they eat large quantities of food.