BMR Explained: Basal Metabolic Rate and How to Calculate It
BMR is how many calories your body burns at rest. See the Mifflin-St Jeor formula, examples, what affects BMR and why you shouldn't eat below it long term.
By Ayoub Farid · · 2 min read
Your basal metabolic rate (BMR) is the number of calories your body needs to keep you alive at complete rest: breathing, circulation, brain function and keeping cells running. It's usually the largest part of your daily calorie burn.
How to calculate BMR
The Mifflin-St Jeor equation is widely used and considered one of the more accurate formulas for most adults:
- Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5
- Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) − 161
Examples
| Person | Calculation | BMR |
|---|---|---|
| Woman, 28, 165 cm, 60 kg | 600 + 1,031 − 140 − 161 | ~1,330 kcal |
| Woman, 45, 170 cm, 80 kg | 800 + 1,063 − 225 − 161 | ~1,477 kcal |
| Man, 30, 178 cm, 80 kg | 800 + 1,113 − 150 + 5 | ~1,768 kcal |
| Man, 50, 185 cm, 100 kg | 1,000 + 1,156 − 250 + 5 | ~1,911 kcal |
What affects BMR
- Body size: larger bodies burn more.
- Muscle mass: muscle uses more energy than fat at rest.
- Age: BMR declines gradually, partly due to muscle loss.
- Sex: men typically have higher BMR due to size and muscle.
- Genetics and hormones: thyroid function and other factors play a role.
BMR vs. TDEE
BMR is only the resting part. To get total daily calories, multiply BMR by an activity factor; see TDEE explained.
Should you eat below your BMR?
Your target for weight loss is usually below your TDEE but often still above BMR. Eating far below BMR for long periods makes it hard to get enough protein and nutrients and is difficult to sustain. Very low-calorie diets should be supervised by a doctor. See is 1200 calories too low.
Can you raise your BMR?
Modestly. Building muscle through strength training raises resting energy use a little. Eating enough protein supports that. There are no foods or supplements that meaningfully "boost metabolism" on their own.
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Frequently asked questions
What is a normal BMR?
Many adult women fall around 1,200–1,500 kcal and men around 1,500–2,000 kcal, but it varies with size and age.
Is BMR the same as calories burned per day?
No. BMR is only at rest; total daily burn (TDEE) is higher.
Which BMR formula is most accurate?
Mifflin-St Jeor is commonly recommended for most adults.
Does dieting lower BMR?
Losing weight lowers BMR somewhat because a smaller body uses less energy.
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