L.I.D. Limited Ingredient Diets® Grain Free Chicken & Sweet Potato Formula. Formulated with a limited list of premium protein and carbohydrate sources, this L.I.D. Limited Ingredient Diets® formula is excellent when you are seeking alternative ingredients for your pet. L.I.D. Limited Ingredient Diets® Chicken & Sweet Potato Dry Dog Formula is a grain-free diet that’s also designed to maintain your dog’s digestive health while supporting healthy skin and a shiny, luxurious coat.