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Understanding Basal Metabolic Rate (BMR)
5 min read
Basal Metabolic Rate (BMR) is the minimum number of calories your body needs to sustain basic physiological functions—breathing, circulation, cell repair, and organ function—while at complete rest. It typically accounts for 60–75% of total daily calorie expenditure in sedentary individuals.
Why BMR Matters
Knowing your BMR helps you:
• Set a realistic lower limit on calorie intake (eating far below BMR is counterproductive and harmful)
• Understand how different factors affect metabolism
• Calculate TDEE (total daily energy expenditure) by applying an activity multiplier
Common BMR Equations
Mifflin-St Jeor (recommended as the most accurate for most adults):
• Men: (10 × kg) + (6.25 × cm) − (5 × age) + 5
• Women: (10 × kg) + (6.25 × cm) − (5 × age) − 161
Harris-Benedict (older, slightly less accurate):
• Men: 88.362 + (13.397 × kg) + (4.799 × cm) − (5.677 × age)
• Women: 447.593 + (9.247 × kg) + (3.098 × cm) − (4.330 × age)
Katch-McArdle (uses lean body mass—more accurate if you know your body fat %):
BMR = 370 + (21.6 × Lean Body Mass in kg)
What Affects BMR
• Muscle mass: Muscle burns more calories at rest than fat tissue. More muscle = higher BMR.
• Age: BMR tends to decrease with age, partly due to muscle loss.
• Sex: Men generally have higher BMR than women, largely due to greater average muscle mass.
• Body size: Taller, heavier people have higher absolute BMR.
• Hormones: Thyroid hormones directly regulate metabolic rate. Hypothyroidism can significantly lower BMR.
• Temperature: Living in cold environments slightly elevates BMR.
Can You Raise Your BMR?
To a meaningful degree, yes. The most effective strategy is building and preserving muscle through resistance training. Muscle tissue has higher resting metabolic activity than fat tissue, so increasing your muscle-to-fat ratio raises BMR over time. Protein intake also has a higher thermic effect (the energy cost of digesting food) than carbohydrates or fat.
Try the BMR Calculator.
Frequently Asked Questions
Is BMR the same as resting metabolic rate (RMR)?
They are similar but not identical. BMR is measured under very strict conditions (fasted state, thermoneutral environment, complete physical rest). RMR is measured at rest but under less strict conditions. RMR is typically 10–20% higher than BMR. Most online calculators technically compute RMR.
Does eating more frequently boost BMR?
No. The total thermic effect of food is determined by total calorie and macronutrient intake, not meal frequency. Eating the same calories in 3 meals or 6 meals produces the same metabolic effect.