There are a few different strategies you can use to keep cats from eating your Christmas tree. One option is to secure the tree in place so it doesn't fall over, which would prevent the cat from trying to climb it. Additionally, you could also use a spray or scented oil that cats don't like on the tree to deter them from approaching it. Another option is to provide an alternative source of entertainment, such as cat toys or a scratching post, to distract the cat from the tree. Finally, you could also try training the cat to stay away from the tree using positive reinforcement techniques such as treats or praise.