The macronutrient calorie distribution in 12 oz of Fat Free Skim Milk are 60% in carbs, 0% in fat, and 40% in protein.
This ratio can give you a sense of if this food is higher in carbs or lower in carbs than other foods by weight. Eating foods high in carbs can cause your blood glucose to spike faster than if the food or meal you're eating also contains protein or fat.
This ratio can estimate how much water this food contains relative to other foods. Water helps regulate body temperature, lubricate joints, flush out waste products, and protect our organs and tissue. Eating foods high in water can help you stay hydrated.