Free Metabolism Calculator

Metabolism Calculator — BMR by Age

Find out how fast your metabolism is and how it compares to average for your age.

Calculate My Metabolism ↓

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Uses the Mifflin-St Jeor formula — the most accurate BMR equation for healthy adults.

Why metabolism slows with age

1

Muscle loss (sarcopenia)

After 30, adults lose 3–8% of muscle per decade without resistance training, reducing BMR.

2

Hormonal changes

Declining sex hormones reduce anabolic drive, making muscle maintenance harder with age.

3

Reduced physical activity

NEAT decreases with age — less spontaneous movement reduces daily calorie burn by 200–400 kcal.

4

How to fight back

Resistance training, high protein, staying active, and quality sleep are the best counters.

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