METABOLISM
Definition:
Meta means changing or transforming
Metabolism refers to the entire network of chemical processes in
maintaining life
 2 separate pathways
o Catabolism – breaking down complex molecules into simpler ones
o Anabolism -building complex molecules (living tissue) from simple ones
 Main function of metabolism is to maintain homeostasis (maintaining balance
in the body’s internal environment e.g. blood glucose) (see Ch. 14 in Food
Science).
Metabolic Rate: refers to the rate at which the body’s chemical processes occur
Variations in Metabolic Rate do occur due to variations in
 Body temperature
 Body size (determined by genetic, behavioural, environmental factors)
 Physical development and age
 Body composition and sex
 Supply of energy available to the body (conservation/survival)
Metabolism and Weight Management: metabolic rate influences weight
maintenance
 Basal metabolism – energy used by body at rest to maintain automatic lifesupporting processes such as breathing, maintaining body temperature,
regulating heartbeat, as well as cellular processes.
o BMR consumes about 2/3 of your body’s energy
 Voluntary Activities – consumes the remaining 1/3 of body’s energy
o Includes all physical activity – sedentary, light, moderate, vigorous
 Weight-loss Diets – body switches to ‘survival mode’ (SET POINT)
 Physical exercise – increases metabolic rate