Metabolism refers to the chemical reactions that take place in the bodys cells that change food into energy. It is a complex process that combines calories and oxygen to create and release energy, which fuels body functions such as breathing, circulating blood, digesting food, growing and repairing cells, managing hormone levels, and regulating body temperature. Thousands of metabolic reactions happen at the same time, all regulated by the body, to keep our cells healthy and working.
After we eat food, the digestive system uses enzymes to break down proteins into amino acids, turn fats into fatty acids, and turn carbohydrates into simple sugars like glucose. The body can use sugar, amino acids, and fatty acids as energy sources when needed. These compounds are absorbed into the blood, which carries them to the cells. After they enter the cells, other enzymes act to speed up or regulate the chemical reactions involved with "metabolizing" these compounds. During these processes, the energy from the food is converted into a form that the body can use.
Metabolism comprises two major parts: anabolism (building up, also called biosynthesis) and catabolism (breaking down) . The exact nature of catabolic and anabolic pathways varies from organism to organism, but all living organisms use metabolism to extract energy from their environments and use it to carry out activities such as movement, growth and development, and reproduction. The rate of energy production is called the basal metabolic rate (BMR), which refers to the minimum number of calories your body needs to function while you’re resting.
