What is the metabolic rate associated with maintaining vital functions and often makes up a significant percentage of TDEE?

The metabolic rate responsible for maintaining vital functions in the body is the Basal Metabolic Rate (BMR), which reflects the energy expenditure needed for essential physiological processes such as breathing, circulation, cell production, and temperature regulation. BMR constitutes a substantial portion of the Total Daily Energy Expenditure (TDEE), typically accounting for about 60-75% of the total energy burned in a day, depending on factors like age, sex, and body composition.

Resting Metabolic Rate (RMR) is often mistakenly interchanged with BMR, but while they are similar, RMR can include additional factors, such as the energy used during the digestive process and activities not accounted for in a strict resting state. Although RMR is indicative of someone's caloric needs while at rest, it usually is measured under less controlled conditions compared to BMR. Therefore, while RMR is also an important component of TDEE, it does not specifically target the minimum energy required to sustain just vital functions in a fully rested state, which is what distinguishes BMR.