Basal metabolic rate (BMR)
Your basal metabolic rate is the energy your body uses at complete rest – usually 60 to 70% of your daily energy needs.
Ausführlich erklärt
Your basal metabolic rate (BMR) is the amount of energy your body uses when you do absolutely nothing – lying down, awake, on an empty stomach and at a comfortable room temperature. It keeps your heart, lungs, liver, kidneys and brain running, regulates your body temperature and renews cells. For most people it accounts for 60 to 70% of total daily energy expenditure – more than exercise and everyday movement combined.
How high your BMR is depends mainly on your height, weight, age and sex – and especially on your fat-free mass (everything except fat: muscles, organs, bones, water), because muscles and organs burn considerably more energy at rest than fat tissue. The liver accounts for around a quarter and the brain for around a fifth of resting energy use, even though together they weigh only a few kilos.
BMR can be calculated with formulas that were calibrated against measured values. The Mifflin-St Jeor equation (1990) is now considered the most accurate for most adults: men calculate 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5; women use the same formula with − 161 instead of + 5. A 35-year-old woman weighing 70 kg and measuring 168 cm comes out at around 1,410 kcal, a 40-year-old man weighing 85 kg and measuring 180 cm at about 1,780 kcal. The older Harris-Benedict equation (revised in 1984) gives similar results. For most people the formula is less than ten per cent off the measured value, for some considerably more – formulas are a good estimate, not a lab result.
Important for weight loss: your BMR is the lower limit. If you eat less than your body needs at rest over a long period, you risk losing muscle, nutrient deficiencies and constant tiredness – and your body responds by turning down its energy use. A sensible deficit is therefore based on your total daily energy expenditure (TDEE), not on your BMR.
In children and teenagers, BMR per kilo of body weight is considerably higher than in adults, because growing takes energy. There are separate formulas for them – and no reason to cut calories.