Force-feeding your cat is stressful for them and potentially dangerous for you. If a cat doesn't eat for 24-72 hours, that's the time you start to find a way to force the cat to eat. Try dribbling a thin slurry of cat food into his mouth using a syringe. Also, try to encourage your cat to eat commercially canned food. You may find heating the food or mixing in fish broth, making sure it does not contain onions, which can be toxic to cats, or cooked egg could entice your picky cat to eat.