Do you know how much you've actually been eating? A lot of people find that they become full very quickly eating this way, and actually eat a lot less than they used to without being hungry. It's good for people who do have a decent amount of weight to lose, but for people like you, it's a different kind of problem! Are you eating fatter cuts of red meat? Cooking things in butter and bacon grease? Adding a good amount of fat to salads in the form of olive oil/avocado/nuts/etc? If you're not currently getting 60-70% of your calories from fat, you should try incorporating more fat into every meal to increase your intake without neccessarily adding a lot of bulk to your meals if you're feeling full too quickly.