Rats will eat just about anything. This can be a problem if, like us, you let your rats out to explore outside their cage. They will eat through electrical cables and chew wooden doors, skirting board etc.
We feed our rats a mixture of
They also sometimes get sunflower seeds, popcorn and Millet Spray. They also get trimmings off raw vegetables and some leftovers from our meals.They really like mashed potato, cooked rice and porridge. They need protein in their diet (cheese, meat, Alexander's fingers etc.) but too much is bad for them and makes them smelly.
A particular favourite is corn on the cob - even after we've had a good nibble at it!
Be wary of the rat nuggets! Pet shops sell them suggesting that they are good for the rats because the rats can't just choose the food they like, however most are not very good for rats - they contain a lot of fat and salt. Not to mention the fact that the rats do get bored with them very quickly (well you'd get bored eating the same thing all the time).
I've got to give a special mention here to Rat Rations - it's like Amazon for rat food.