Have you ever wondered how many calories your body burns just by existing? That number is known as your Basal Metabolic Rate (BMR). Understanding your BMR is a foundational step in managing your nutrition and body weight.
Disclaimer: This guide is for educational purposes only and is not intended to prescribe diets or replace professional medical advice.
What is BMR?
Basal Metabolic Rate (BMR) is the total number of calories your body requires to perform basic, life-sustaining functions while at rest. These functions include breathing, circulating blood, cellular growth, and neurological function.
Even if you laid in bed all day without moving a muscle, your body would still burn your BMR worth of calories just to keep you alive. For most people, BMR accounts for about 60% to 75% of their total daily energy expenditure.
How is BMR Calculated?
Because taking a precise measurement of BMR requires restrictive laboratory conditions (like sleeping in a clinical setting and measuring oxygen consumption), health professionals and fitness apps rely on mathematical equations to estimate it.
The most common equations take four primary variables into account:
- Weight: A larger body requires more energy to sustain itself.
- Height: Taller individuals generally have more surface area and larger organs, requiring more energy.
- Age: Metabolic rate typically slows down as you age, partly due to a natural loss of muscle mass.
- Gender: Men generally have a higher BMR than women of the same size because they naturally tend to carry more muscle and less fat.
Find Your Baseline
Calculate your estimated Basal Metabolic Rate based on your personal metrics.
Open BMR CalculatorCommon BMR Equations
There are several equations used to estimate BMR. The Mifflin-St Jeor equation is widely considered one of the most accurate for the general population and is the default used by many modern calculators.
Another popular formula is the Harris-Benedict equation. Though older, it is still frequently used, often yielding a slightly higher calorie estimate than Mifflin-St Jeor.
BMR vs. TDEE
It is important not to confuse BMR with Total Daily Energy Expenditure (TDEE).
Your BMR only accounts for your resting energy. Once you get out of bed, walk around, digest food, or exercise, you burn additional calories. Your TDEE takes your BMR and multiplies it by an activity factor to estimate the total calories you burn in a full, active day. When trying to maintain, gain, or lose weight, your TDEE is the target you want to look at.
Summary
- BMR is the energy your body burns at complete rest.
- It is estimated using your age, gender, height, and weight.
- It serves as the baseline for calculating your total daily caloric needs.