Grain-free cat foods are a marketing phenomenon to try and satisfy cat owners’ desire for a more natural cat food. They are not necessarily any better than other cat foods. One reason is because the manufacturers have substituted grains with other starchy ingredients such as potatoes which contain more carbohydrates. In addition grain carbohydrates can be digested by cats whereas potato carbohydrates are harder to digest. The manufacturers are trying to provide protein and cheap energy. The energy comes from the carbohydrates in grains or potatoes. It is highly confusing. I’m sure other people are also confused.