Mice, birds, insects, lizards, bunnies, carrion, squirrel, rat, prairie dog, so on. Heck, a good bunny will last a couple of days. A squirrel for a day or more. The whole cat sleeping thing is how they conserve energy. Its usually a kill, relax for an hour, hunt, kill, repeat.
I probably keep a bit more meat on my cats then a wild cat would...they are not overweight, but they are not super skinny either. They have a nice 'mouse pouch' as some put it. I also have two super active bengal cats that require more grub then most. I think in the wild they might nap more rather then running around like goof balls all day long chasing wand toys and paper balls.