what atoms are contained in our food
Fats and ethanol have the greatest amount of food energy per mass, 37 and 29 kJ/g (8.8 and 6.9 kcal/g), respectively. Proteins and most carbohydrates have about 17 kJ/g (4.1 kcal/g).The differing energy density of foods (fat, alcohols, carbohydrates and proteins) lies mainly in their varying proportions of carbon, hydrogen, and oxygen atoms.Carbohydrates that are not easily absorbed, such as fiber, or lactose in lactose-intolerant individuals, contribute less food energy.Carbohydrates, fats, and proteins comprise ninety percent of the dry weight of foods. ) Organisms derive food energy from carbohydrates, fats and proteins as well as from organic acids, polyols, and ethanol present in the diet.