How does body mass influence absolute metabolic rate?

Body mass influences absolute metabolic rate because larger bodies generally require more energy to maintain basic physiological functions, such as circulation, respiration, and thermoregulation. This is primarily due to the increased number of cells and greater tissue mass that need energy to sustain their activities. Consequently, as body mass increases, the absolute metabolic rate typically rises, reflecting the greater energy expenditure required to support a larger organism. However, metabolic rate per unit of body mass often decreases with increasing size, meaning larger animals may have a lower metabolic rate relative to their size compared to smaller animals.