I leave cat food out from friday to sunday each week and the possums raccoons eat it how do i stop them?

I cannot take my two cats with me each weekend, so I must leave them home with a bowl of cat food. There are two possums and one raccoon that eat the entire cat feeder in one night leaving my cats without food for the rest of the weekend. How can I stop these critters? I cannot come home at night to take in the food. What do I do?