Basal Metabolic Rate

Your basal metabolic rate is the energy your body spends at complete rest, keeping you breathing, circulating blood, holding your temperature and repairing itself. For most adults it is between 1200 and 1900 calories a day, and it accounts for roughly two thirds of everything you burn.

It is set mostly by how much of you there is, and particularly by how much lean body mass you carry, because muscle and organs cost more to run than fat does. Sex, age and height all move it for the same underlying reason.

The equation most dietitians use is Mifflin-St Jeor, published in 1990, which predicts measured resting energy better than the older Harris-Benedict equation does. Where lean body mass is known, the Katch-McArdle equation uses that instead and does better still for anyone very lean or carrying a lot of fat.

What it is not

It is not what you should eat. Nobody lies still all day, so eating to this figure means eating well under what you actually spend. The number you want for that is your total daily energy expenditure. It is also not fixed: losing weight lowers it, which is part of why a deficit that worked for two months stops working in the third.

Where you see it in FitnessSyncer

Your profile holds this figure, and the rest of the product reads it. Our BMR calculator works one out from your sex, age, height and weight.