I have had this problem in the past. As others have said, place the food bowl in a larger container like a pie plate and put water in the pie plate. Make sure you have at least 2-3 inches of clearing between the bowls as ants are smart and will build a 'bridge' with each other in order to get the food. You can also put out the small cans of ant bait near the food, your cat can't get into the ant traps or access the bait. This should eliminate a lot of you ants.
Also, follow the ants to where their nest is - you will see a long line of ants. Pour boiling hot water down their hole. They will come back, but it will take a couple of days.