A person's basal metabolic rate refers to the minimum calories he needs to survive in the absence of any activity. In other words, Basal Metabolic Rate is the amount of energy expressed in calories that a person needs to keep the body functioning at rest. Some of those processes are breathing, blood circulation, controlling body temperature, cell growth, brain and nerve function and contracting of muscles.

DUE TO THE BASAL
LIFE PROCESSES
About 70% of a human's total energy expenditure is due to the basal life processes within the organs of the body. About 20% of one's energy expenditure comes from physical activity and another 10% from thermogenesis, or digestion of food. All these processes require an intake of oxygen along with coenzymes to provide energy for survival and expel carbon dioxide, due to processing by the Krebs cycle.

IN TISSUES
For the BMR, most of the energy is consumed in maintaining fluid levels in tissues through osmoregulation, and only about one tenth is consumed for mechanical work, such as digestion, heartbeat, and breathing.

CAPACITY TO DO WORK
What enables the Krebs cycle to perform metabolic changes to fats, carbohydrates, and proteins is energy, which can be defined as the ability or capacity to do work.

CATABOLISM
The breakdown of large molecules into smaller molecules- associated with the release of energy- is catabolism. The breakdown of proteins into amino acids is an example of catabolism.

ANABOLISM
The building up process is termed anabolism. The formation of proteins from amino acids is an anabolic process.