Food energy

From ArticleWorld

Food energy is defined as the amount of energy food provides its consumer through digestion. The energy value of food indicates how much value it is to the body as energy. The study of food energy for dietary reasons is known as macrobiotics.


Food energy is typically measured in calories (however, the International System of Units, kilojoule is becoming more common and used solely in some countries, like Australia).

Some food contains more energy than other foods, often foods that are high in fat or sugar have higher energy levels.

The United States Department of Agriculture, also known as the USDA, developed a way to measure food energy in the early 20th century. This process is still being used today.

The food that the USDA is measuring is burned completely in a calorimeter, ensuring that the heat released through the combustion process can be measured. This determines the gross energy value of a specific food. The gross energy value is then multiplied by a coefficient (which the USDA bases on how the human body digests the food in reality).

Energy in food

  • Carbohydrates have 4 nutritional calories/gram.
  • Alcohol has about 7 nutritional calories/gram.
  • Protein has about 4 nutritional calories/gram.
  • Fat, the most energy dense, has about 9 nutritional calories/gram.

Naturally, the participation in sports or high physical activity can influence one's food energy needs and a balance of these energy sources is recommended for optimal balance, and thus optimal health.

Order of consumption

Food energy is burned in a specific order. For example, alcohol calories are burned first since humans can't store alcohol energy. Protein is burned next, followed by carbohydrates. Fat is burned last. Some believe, however, that humans actually burn a mixture of carbohydrates and fat; the ration is dependent on the meals that have been consumed.

It is believed that immediately following meals humans burn more carbohydrates, while between meals they burn more fat.