22/02/2024
Claim: “To determine the amount of carbohydrates in a particular pet food, use this equation: 100% - (% crude protein + % fat + % crude fiber) = % carbohydrates.”
False. First of all this formulation does not take the moisture content of the food into consideration at all, and moisture affects the concentration of all nutrients. Canned food typically ranges around 70-80% moisture, dry food around 6-12%, and fresh food around 65-70%. So you would have to subtract that much from your starting 100% because those percentage points are not carbs.
Second, another big factor in the analysis of a food is its ash content, which has been entirely left out here as well. Ash isn’t some nefarious ingredient added by pet food companies, it is what’s left over after a specific amount of it is incinerated in a laboratory, and represents the amount of minerals present. So for example a food that contains ground bone, bone-in meat, “meat and bone meal”or bone meal will be higher in ash content than something that contains boneless meat only. Overall, any food with a higher meat content, especially from concentrated sources like meat meal made from bone-in meats, will have a higher ash content. Products with a lower meat content, or with plant-based protein sources like corn gluten, will be lower in ash overall.
So a more correct formula to determine carb content would be
100% - (% moisture + % crude protein + % fat + % ash) = % carbohydrates.
So what happened to fiber? Well, fiber is a type of carbohydrate. Fiber can’t be digested by the body, but it has an important function for gut health and certain fiber types also serve as food for the beneficial gut bacteria.
So for the sake of determining the “digestible” portion of carbs in a dog food, you can subtract the amount of fiber from the total derived from the formula, and you’ll have the content of the other two types of carbs: sugars and starches.
Sugars are simple carbohydrates and come for example from food sources like ripe fruit, sweet veggies like sweet potatoes or carrots, or in the form of lactose in dairy products.
Starches are “complex” carbs and come from sources like starchy vegetables and legumes, grains, seeds, and nuts.
Need more help deciphering pet food labels? Take a look here:
This article will give you a quick overview about what the labels on a pet food tell you - and more important what they don't tell you. It is based on the FDA consumer information provided by the Center for Veterinary Medicine (parts are quoted in the grey boxes) and has my own comments added below....