Basal Metabolic Rate

body science · energy · metabolism

Energy at rest. Your body is constantly using energy even when you're sleeping or sitting still. Basal metabolic rate (BMR) measures how much energy your body burns just to keep your heart beating, your lungs breathing, and your brain thinking.

Strict testing rules. To measure BMR properly, scientists need you to be completely relaxed and undisturbed, not digesting any food, and in a comfortable temperature. Even stress or exercise beforehand can change the numbers.

Fish and reptiles differ. Cold-blooded animals like fish and reptiles don't have a basal metabolic rate like warm-blooded mammals do. Instead, scientists measure their standard metabolic rate, which includes the temperature at the time of testing.

Temperature matters for cold-bloods. Because fish and reptiles get their body temperature from their environment, knowing the exact temperature when you measure their metabolism is super important for understanding how much energy they really use.

Your body's idle speed. Think of BMR like a car's idle engine speed. Even when your car isn't moving, the engine still burns fuel to keep running. Your body does the same thing with the food you eat.