Describe basal metabolic rate (BMR) and two factors that influence it?

• A. BMR is the energy expended during exercise; influenced by age and climate.
• B. BMR is the energy expended at rest for basic bodily functions; influenced by age, sex, lean body mass, hormones, and genetics.
• C. BMR is calories burned at meals; influenced by meal composition.
• D. BMR is energy used during sleep; influenced by caffeine and sleep quality.

Answer: (B)

Basal metabolic rate is the energy your body uses at rest to support essential life-sustaining functions like breathing, heartbeat, and organ activity. It’s measured under calm, thermoneutral conditions after fasting to reflect the minimum energy needed to keep you alive without activity or digestion.

Two important factors shaping BMR are lean body mass and hormonal state. Lean body mass drives most of the variation because muscle tissue uses more energy at rest than fat tissue. Hormones, especially thyroid hormones, can ramp up or slow down metabolism, influencing how quickly your body burns calories. Age also matters, with BMR tending to decrease as people get older due to changes in lean mass and hormonal balance, and genetics can set a baseline rate as well.

The other descriptions refer to energy used during exercise, meals, or sleep—different components of total energy expenditure, not BMR.