In order to function properly, and complete tasks both basic and complicated, the human body requires energy in the form of calories. Every organ in the human body needs energy to function, and it is essential in order to keep all the systems in the body up and running.

The Body’s Cells

The energy contained in calories is converted into the nucleotide Adenosine Triphosphate by the cells in the body. This, in turn, provides the energy that most cells need in order to complete their respective functions and processes, such as the transmission of neural signals, the transport of materials in and out of the cell, maintenance of cell volume, and cellular reproduction. Without energy, the body would not be able to perform all these minute functions, and without the functions and processes, the body’s cells will begin to die.


Muscles aren’t solely for the purpose of playing sports or weight lifting – muscles are essential in order to keep any human body alive. The cardiac muscle in the heart, for example, keeps the heart pumping, while muscles also line the digestive tract and other organ systems in the body. The chemical energy which the body obtains from calories is essential in order to keep muscles functioning, and allow them to relax and contract. Without energy, the muscles in the body would cease to function altogether.

Tissues And Organs

Tissues and organs are vital parts of the human body, and both are composed of groups of cells joined together. The skin, for example, is a body tissue, and all other organs, such as the heart, kidneys, and lungs, are made of tissue. In order to repair damaged tissue and build new tissue, the body requires energy. If the body is suffering from malnutrition and deprived of energy, its capacity to heal both internally and externally will be greatly reduced, and continued malnutrition can be fatal.

Chemical Reactions

The body contains several systems that trigger hormones for controlling chemical reactions in the human body. The endocrine system, for example, releases hormones that trigger the process of childbirth and hormones that are related to digestion, among many others. If the body is deprived of caloric energy, this system cannot function and will eventually shut down.

Fat Storage

Fat is generally considered undesirable – it is deemed part of unhealthy diets, considered the source of all ill health, and is seen as the culprit in making physiques unattractive. However, the body needs a certain amount of fat in order to stay healthy. Caloric energy that is unused is stored as fat in the body, and this fat can come in useful for providing warmth to the body, protecting the organs, and can even be used by the body as an energy source when there is a lack of food.