Look at Pet Food Like Human Food - The "How To" for Translating Pet Food Labels into Calories.

I've been fortunate to participate in the amazing BK Pets book tour recently and in our many adventures together we talk with pet parents about the macronutrient calories (protein, fat, carbohydrates) in pet food.

Without a calculator, the Guaranteed Analysis on pet food labels is useless.  There is nothing represented on that label that will tell you how many protein, fat or carbohydrate calories are in the package.  Yet this is exactly how human nutritionists evaluate human food.  There is also nothing on that label that will ostensibly enable you to compare one food to another - especially if those foods have different moisture levels.  

Ancestral diets for dogs, which are recognized as the gold standard by many pet food formulators, start at 49% of calories from protein.  So how do you determine that?  Grab your favorite pet food, a calculator and follow along.

The example below will enable you to understand how to calculate protein, fat and carb calories for your own pet food.  This example comes from a gently cooked recipe for dogs from Goodness Gracious®

Guaranteed analysis
Protein (min):	18%
Fat (min):	5%
Fiber (max):	1%
Moisture (max):	72%
Ash (max):	1%

 

1. Calculate carbohydrate content:  Add protein, fat, fiber, moisture, and ash, and subtract that sum from 100.  If ash is not listed estimate 2% for wet food and 6% for dry food.

100 – (18+5+1+72+1) = 3%

This food has 3% digestible carbs. These are the carbs with calories.  (It excludes the 1% fiber value as there are no calories in fiber.)

 

2. Total the calories for protein, fat and carbs in 1 gram of food. To do this you need to know that every gram of protein and carbohydrate has four calories, and every gram of fat has nine calories.

 

Protein:      .18 x 4 = .72

Fat:              .05 x 9 = .45

Carb:           .03 x 4 = .12

Total:           .72 + .45 + .12 = 1.29

 

3. Calculate the % of calories that come from protein, fat, and carb.

Protein:      .72/1.29 = 56%

Fat:            .45/1.29 = 35%

Carb:          .12/1.29 = 9%

Total:          100%

 

This diet provides 56% of the calories from protein, 35% from fat and only 9% from carbohydrates.  It has an excellent macronutrient profile that is high protein, moderate fat, and low carb. (Tip: the values you calculate are close estimates as the guaranteed analysis reports minimum and maximum percentages.)

Here is the math summarized in table form: 

	As Fed % (Label values)	Atwater value	Math Step 1	Math Step 2	Kcal %
Protein:	18%	4	.18*4 = .72	.72 / 1.29	56%
Fat:	5%	9	.05*9 = .45	.45 / 1.29	35%
Digestible (Net) Carb	3%	4	.03*4 = .12	.12 / 1.29	9%
Total:			.72+.45+.12 = 1.29		100%