text:  It's not just about digestive upset. Everyone knows that if you're switching the feed, you do it gradually over seven to ten days. But what they don't realize is that dog's system is kind of like going on one of those no-carb diets for people or whatever. Your system actually changes. And to switch to a higher-carbohydrate diet in the summer and then switch to a higher-fat diet in the winter, truly you're not doing your dog any favors. You're better off just keeping the dog on a higher-protein and fat diet