Energy Density

Energy density is the amount of food energy contained in a given weight of food, usually expressed as kilocalories or kilojoules per gram. A food with high energy density supplies more energy in a small weight, while a food with low energy density supplies less energy for the same weight. It is a property of the food or diet, not a measure of portion size by itself .¹

Water has a strong influence on energy density because it adds weight without adding calories. Fat tends to raise energy density because it provides about 9 kilocalories per gram, compared with about 4 kilocalories per gram for protein and digestible carbohydrate. Fiber can also lower energy density by contributing mass with relatively little metabolizable energy. Cooking and processing can change energy density by altering water content or ingredient proportions .¹

Energy density should be distinguished from nutrient density. Energy density describes calories relative to food weight, whereas nutrient density describes the amount of vitamins, minerals, protein, or other nutrients relative to energy, weight, or serving size. A food can therefore be energy-dense and still contain important nutrients, or be low in energy density without being nutritionally complete. The term is most useful for describing how concentrated a food's energy is .¹