Published on August 08, 2026 • Last updated August 08, 2026
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Basal Metabolic Rate (BMR) is the number of calories your body needs each day to perform basic, life-sustaining functions such as breathing, circulation, and cell repair while completely at rest.
Even if you spent an entire day lying in bed without moving, your body would still burn a significant number of calories. That number is your Basal Metabolic Rate (BMR) — the baseline energy your body needs to keep vital functions like breathing, blood circulation, cell production, and temperature regulation running smoothly. BMR typically accounts for 60-75% of the total calories most people burn in a day, making it the largest single component of daily energy expenditure — larger than exercise or digestion. Because of this, BMR is the foundation most calorie and diet calculators build on.
The most common way to estimate BMR is the Mifflin-St Jeor equation, which uses your weight, height, age, and sex. Muscle tissue burns more calories at rest than fat tissue, which is why men — who typically carry more muscle mass — tend to have a higher BMR than women at the same weight, and why BMR naturally declines with age as muscle mass tends to decrease. Knowing your BMR is useful because it's the starting point for any calorie-based goal. To maintain your current weight, you need to eat roughly enough to cover your BMR plus the calories burned through daily activity — a total known as Total Daily Energy Expenditure (TDEE).
To lose weight you eat below that total; to gain weight, above it. BMR is an estimate, not an exact measurement — real metabolic rate varies with genetics, muscle mass, and hormones — but it gives a reliable, evidence-based starting point for setting realistic nutrition and fitness goals.
Learn how BMR is calculated
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TDEE is the total number of calories your body burns in a day — at rest and through activity. It is the master number behind every effective diet and fitness plan. This guide explains how TDEE is calculated and why it matters more than BMR alone.
Most people confuse BMR and TDEE — and eating at your BMR instead of your TDEE is the #1 calorie calculation mistake. This guide explains the difference and tells you exactly which number to use for your goal.
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