Why Does Everyone Keep Talking about Metabolism?


Catabolism - the breakdown of molecules to obtain energy

Anabolism - the synthesis of all compounds needed by the cells


Nutrition, metabolism and energy





Carbohydrates in metabolism

Foods supply carbohydrates in three forms: starch, sugar, and cellulose (fiber). Starches and sugars form major and essential sources of energy for humans. Fibers contribute to bulk in diet. Body tissues depend on glucose for all activities. Carbohydrates and sugars yield glucose by digestion or metabolism.

The overall reaction for the combustion of glucose is written as:

C6H12O6 + 6 O2——-> 6 CO2 + 6 H2O + energy

Most people consume around half of their diet as carbohydrates. This comes from rice, wheat, bread, potatoes, pasta, macaroni etc.

Proteins in metabolism

Proteins are the main tissue builders in the body. They are part of every cell in the body. Proteins help in cell structure, functions, haemoglobin formation to carry oxygen, enzymes to carry out vital reactions and a myriad of other functions in the body. Proteins are also vital in supplying nitrogen for DNA and RNA genetic material and energy production.

Proteins are necessary for nutrition because they contain amino acids. Among the 20 or more amino acids, the human body is unable to synthesize 8 and these are called essential amino acids.

The essential amino acids include:










Fat in metabolism

Fats are concentrated sources of energy. They produce twice as much energy as either carbohydrates or protein on a weight basis. Helping to form the cellular structure; forming a protective cushion and insulation around vital organs; helping absorb fat soluble vitamins, providing a reserve storage for energy Essential fatty acids include unsaturated fatty acids like linoleic, linolinic, and arachidonic acids. These need to be taken in diet. Saturated fats, along with cholesterol, have been implicated in arteriosclerosis and heart disease.

Minerals and vitamins in metabolism

The minerals in foods do not contribute directly to energy needs but are important as body regulators and play a role in metabolic pathways of the body. More than 50 elements are found in the human body. About 25 elements have been found to be essential, since a deficiency produces specific deficiency symptoms.

Important minerals include:






chloride ions








Vitamins are essential organic compounds that the human body cannot synthesize by itself and must therefore, be present in the diet. Vitamins particularly important in metabolism include:

Vitamin A

B2 (riboflavin)

Niacin or nicotinic acid

Pantothenic Acid etc.

Metabolic pathways

The chemical reactions of metabolism are organized into metabolic pathways. These allow the basic chemicals from nutrition to be transformed through a series of steps into another chemical, by a sequence of enzymes.

Enzymes are crucial to metabolism because they allow organisms to drive desirable reactions that require energy. These reactions also are coupled with those that release energy. As enzymes act as catalysts they allow these reactions to proceed quickly and efficiently. Enzymes also allow the regulation of metabolic pathways in response to changes in the cell’s environment or signals from other cells.

Written By: Nelson Lopes