Dogs have no nutritional requirement for carbohydrates, yet premium dog food is loaded with them (most premium dog food is made up of 40% to 60% carbohydrates). Pet food companies do this because carbohydrates are generally less expensive than animal protein, and the starch in the carbs is a great way to bind the kibble together during manufacturing.
The shift to grain-free dog food has only exacerbated this problem. When the dog food companies removed the grains from dog food they replaced them with other carbohydrates. Some, like tapioca starch and white potatoes, are actually worse for a dog’s diet than the grains they replaced because they are extremely high in starch and sugar.
Compounding the carbohydrate problem is the fact that you can’t tell the amount of carbs in your dog’s food from the label on the package. That’s because pet food companies are not required to disclose the carbohydrate level in their foods (so none of them do).