The complete set of chemical reactions that occur within a living organism or cell to maintain life and carry out its functions.
Metabolism includes reactions that break down substances to release or transfer energy, as well as reactions that use energy to build and maintain cellular structures. It is therefore not simply another word for “burning calories.”
Metabolism is influenced by factors such as age, hormones, nutrition, physical activity, genetics, illness, and medications. The metabolic processes occurring in different tissues can also vary considerably.
QUICK FACT
Metabolism includes both catabolism and anabolism: one generally breaks substances down, while the other builds substances up.
COMMONLY CONFUSED WITH
Metabolic rate: Metabolism refers to the overall network of chemical reactions in the body; metabolic rate refers to the rate at which energy is being used or metabolic processes are occurring.
SEE ALSO
- Catabolism
- Anabolism
- Cellular Respiration
- ATP
- Mitochondria
