ABSTRACT
Metabolic rate is usually determined by measuring oxygen consumption. Therefore it is natural that muscular exertion would be a major factor affecting metabolic rate.
Another factor to consider is environmental temperature. If it falls below body temperature, heat conserving mechanisms kick in (i.e. cutaneous vasoconstriction and shivering). This causes the metabolic rate to rise. When environmental temperature increases to a point where it is high enough to raise body temperature, metabolic enzyme action accelerates. Therefore metabolic rate rises with an increase in body temperature.
Other factors affecting metabolic rate include emotional state, height, weight and circulating levels of hormones such as adrenaline and thyroxine, but not insulin.
