The Functionality of Metabolism

Metabolism is the whole sum of reactions that occur throughout the body within each cell to provide the body with energy and maintain life. The process of metabolism is where the body turns the food that is eaten into energy. Metabolism is all the chemical processes that go on in the body to keep the host alive. These are things like organ repairing, breathing, cell repair, digestion, etc. The minimum energy required for all these processes at rest is known as the basal metabolic rate. The energy created is used for vital physiological and biochemical processes and the synthesis of new material. All the chemical reactions by which metabolism can occur is almost the same in all species including animals’ plants' bacteria and fungi. Metabolism is carried out by specific coenzymes and cofactors under specific environmental conditions. The energy currency for the cells is called ATP. Energy homeostasis is critical for the survival of species. The liver is a vital organ that regulates a huge chunk of metabolisms such as carbohydrates, lipids, and proteins. The metabolism and interconversion of the compounds by the liver cells are highly impacted by hormones and the individual’s nutritional state.


Catabolism is the breakdown of complex molecules into smaller molecules, which is usually used for energy release. The most important aspect of catabolism is the release of energy that's stored in the body in the form of ATP (Adenosine triphosphate). Catabolism is an exergonic reaction whereas anabolism is an endergonic reaction. In the first stage of catabolism, large complex molecules are broken down into smaller particles where a tiny amount of energy is released in the form of heat. In the second stage, those smaller molecules are oxidized to release energy as ATP.

Anabolism is the process by which various compounds are synthesized and then used as cell components as well as energy. Anabolism is made possible by catabolism which provides you with the energy.


Anabolism is a vital part of metabolism whereby substances are formed so they can be used later for energy. In the process of anabolism, monosaccharides and amino acids can be formed in the first stage, those same products are activated in the second stage into polysaccharides and proteins. Adenosine triphosphate (ATP) is composed of an adenine ring, three phosphates and ribose sugar. It is the energy currency of the cell. If a cell needs to spend energy to accomplish a task, the ATP molecule will split off one of its three phosphates to become Adenosine diphosphate (ADP). ADP can be converting it back to ATP so that it can be used again.


Metabolism or the metabolic rate is defined as a series of chemical reactions that occurs in all living organisms that create and break down energy necessary for life. This is also described as the rate at which the body expends energy or burns calories. The body can burn calories in several ways through exercise, through the energy required for the daily processes, even at rest. This is known as the basal metabolic rate (BMR). Metabolism can vary from person to person and can be partly genetic. Some people inherit genes that can promote a faster metabolism but regardless of the speed of your metabolism, the body is designed to store excess energy in fat cells. This is where the concept, "calories in must equal calories out" comes from. Since excess energy is stored in the fat cells, one who eats more than they expend will tend to store more in their fat cells, but if one eats fewer calories than those that are burnt throughout the day, then they tend to lose more weight because excess energy isn’t stored as much as it would be if one ate more calories.

The concept of boosting the metabolism has become a highly talked about concept in terms of weight loss however, it’s about improving metabolism if one is focused on weight loss. The rate at which someone’s body carries out metabolic functions cannot be sped up, but it can be improved. Eating nutrient-dense foods, exercising, hydrating, and getting proper rest can all improve metabolism. Research has found that people that are struggling to lose weight may have a leptin issue. Leptin is a hormone produced primarily by fat tissue and it plays a huge role in weight regulation. Leptin’s role is to send signals to the brain that there is enough stored fat, this, in turn, creates a feeling of satiety or feeling full so this signals the body to burn calories. Overall, leptin prevents overeating, there are a few leptin resistance genes that people can inherit. This can put them at risk of developing obesity. People who are obese tend to have higher levels of leptin compared to those who are not obese. However, high levels aren’t a good thing - if leptin is high then this means that the brain cannot respond to the hormonal signals, so the brain still thinks you’re hungry, this is known as leptin resistance. Leptin resistance can contribute to overeating and energy storage which means that calories are burned at a slower rate.

The brain is a high functioning organ, and it requires about 20 percent of the body’s energy and neurons consume 75%–80% of the energy produced in the brain. The brain is always functioning even during sleep. The brain is prioritized for glucose because it does not have a reserve of energy stored away to use when it needs it. The brain has to be constantly supplied with oxygen and energy to run properly.

The interaction between the immune system and metabolism is a delicate, dynamic process. This interaction has not always been understood but researchers have found that metabolism and immunity are intertwined. Basic functions of the immune cells can be regulated through metabolic pathways that are responsible for supporting energy demands. Small alterations in cellular metabolism can influence immune cell function and vice versa; the immune cell function can determine the metabolic state. Undernutrition can lead to immunosuppression, which leads to an increased risk of infection and decreased protection against autoimmune diseases and infection. The cells of the immune system heavily rely on metabolic products for regular immune functions. Hormones regulate metabolism and have a big role in the immune system's regulation. For instance, leptin has been found to play a role in the development and maturation of hematopoietic cells, and leptin deficiency has been associated with loss of cell-mediated immunity. Hematopoiesis is the process through which the body manufactures blood cells. Metabolism and immunity can be manipulated under various circumstances; understanding the link can pave the way for many therapies for various ailments.

Alwarawrah, Y., Kiernan, K., & MacIver, N. (2018, April 27). Changes in nutritional status impact immune cell metabolism and function. Retrieved April 05, 2021, from

Berkheiser, K. (2018, November 06). Can leptin supplements help you lose weight? Retrieved April 05, 2021, from

Raichle ME, Gusnard DA. Appraising the brain's energy budget. Proc Natl Acad Sci U S A. 2002;99(16):10237-10239. doi:10.1073/pnas.172399499

Sapkota, A. (2021, March 09). Anabolism vs catabolism- definition, 13 key Differences, Examples. Retrieved April 05, 2021, from

When immunology meets metabolism... a match for immune disease? (n.d.). Retrieved April 05, 2021, from

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