"BMR," the energy your body uses while completely at rest, stands for what?

“BMR,” the energy your body uses while completely at rest, stands for Basal Metabolic Rate. It is the energy required to keep essential functions running, including breathing, blood circulation, brain activity, temperature regulation, and cell maintenance.

BMR is measured under strict conditions: a person must be awake, physically and psychologically relaxed, in a comfortable temperature, and not actively digesting food. The more commonly discussed resting metabolic rate, or RMR, is similar but measured under less restrictive conditions and may be slightly higher.

BMR varies with body size, age, sex, hormones, illness, and lean body mass. Muscle tissue generally uses more energy at rest than fat tissue. In 1919, researchers J. Arthur Harris and Francis G. Benedict published a widely used equation for estimating BMR from height, weight, age, and sex. BMR is only one part of daily energy expenditure; physical activity and digestion also contribute substantially.