Question 1

How do I calculate my BMR?

Accepted Answer

To calculate your BMR, enter your age, gender, height, and weight into the calculator above. The Mifflin-St Jeor equation is the default and most accurate formula for most people: Men: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) + 5. Women: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) - 161. If you know your body fat percentage, you can switch to the Katch-McArdle formula for potentially more accurate results.

Question 2

What is a good BMR for my age?

Accepted Answer

BMR varies significantly by age, gender, weight, and height, so there is no single 'good' number. As a rough guide: a 25-year-old male at 70 kg and 170 cm has a BMR of about 1,650 kcal/day; a 25-year-old female at 60 kg and 165 cm has a BMR of about 1,370 kcal/day. BMR decreases by roughly 1-2% per decade after age 20. The best approach is to calculate your personal BMR and compare it to your actual energy needs.

Question 3

What is the difference between BMR and TDEE?

Accepted Answer

BMR (Basal Metabolic Rate) is the calories your body burns at complete rest — just breathing, circulating blood, and maintaining body temperature. TDEE (Total Daily Energy Expenditure) is your total calorie burn including all daily activities and exercise. TDEE = BMR × Activity Factor. For weight management, TDEE is what matters: eat less than your TDEE to lose weight, eat more to gain weight, and eat at your TDEE to maintain.

Question 4

How accurate are BMR calculators?

Accepted Answer

The Mifflin-St Jeor equation is accurate to within about 10% for most people. However, individual variation can be 5-15% due to genetics, hormones, medications, muscle mass, and metabolic conditions like hypothyroidism. For the most precise measurement, indirect calorimetry in a clinical setting can measure your actual resting metabolic rate. Use calculator results as a starting point, then adjust based on real-world results over 2-4 weeks.

Question 5

Why do different formulas give different BMR values?

Accepted Answer

Each formula uses different variables and weights them differently. Mifflin-St Jeor uses weight, height, age, and gender. Katch-McArdle uses lean body mass only, making it gender-neutral and more accurate for people with unusual body compositions (very lean or very muscular). The original Harris-Benedict equation (1919) tends to overestimate by 5-15%. Differences of 50-200 calories between formulas are normal and expected.

Question 6

Is it safe to eat below my BMR for weight loss?

Accepted Answer

Eating below your BMR for extended periods is not recommended. Your BMR represents the minimum energy your body needs for survival functions. Sustained under-eating below BMR can trigger adaptive thermogenesis (metabolic slowdown), muscle loss, hormonal disruption, fatigue, and nutrient deficiencies. Instead, create a moderate calorie deficit from your TDEE (250-750 calories below) while ensuring you stay above your BMR.

Question 7

Does BMR decrease with age?

Accepted Answer

Yes. BMR typically decreases by 1-2% per decade after age 20, primarily due to loss of lean muscle mass (sarcopenia). By age 50, your BMR may be 100-200 calories lower than at age 20. However, this decline is largely preventable through regular resistance training, adequate protein intake (1.6-2.2g per kg of bodyweight), and maintaining an active lifestyle.

Question 8

How can I increase my BMR?

Accepted Answer

The most effective way to increase BMR is building lean muscle mass through resistance training — each pound of muscle burns about 6 calories per day at rest compared to 2 calories for fat. Other evidence-based strategies include: getting 7-9 hours of quality sleep, eating enough protein, staying hydrated, avoiding crash diets (which lower BMR), and including high-intensity interval training (HIIT) in your exercise routine.

Question 9

What is the Mifflin-St Jeor equation?

Accepted Answer

The Mifflin-St Jeor equation is a formula for calculating Basal Metabolic Rate published in 1990. For men: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5. For women: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) - 161. It is considered more accurate than older formulas like Harris-Benedict, especially for overweight individuals, and is recommended by the American Dietetic Association.

Question 10

How often should I recalculate my BMR?

Accepted Answer

Recalculate your BMR when: your weight changes by 3-5 kg (7-10 lbs), your activity level changes significantly, your body fat percentage changes noticeably, or every 30-60 days during an active weight loss or muscle gain phase. Also recalculate after major life changes like pregnancy, illness, or starting/stopping medications that affect metabolism.

Question 11

If I have high muscle mass, which formula should I use?

Accepted Answer

Use the Katch-McArdle formula with an accurate body fat estimate. Unlike Mifflin-St Jeor, Katch-McArdle calculates BMR from lean body mass (370 + 21.6 × LBM in kg), so it accounts for your higher proportion of metabolically active tissue. Mifflin-St Jeor may underestimate BMR for muscular individuals because it doesn't directly consider body composition.

Question 12

Is BMR the same as RMR?

Accepted Answer

BMR and RMR (Resting Metabolic Rate) are similar but not identical. BMR is measured under strict conditions: after 8 hours of sleep, 12 hours of fasting, in a temperature-controlled room. RMR is measured under less strict conditions and is typically 10-20% higher than BMR because it includes the energy cost of recent food digestion. In practice, most online calculators estimate RMR-like values using BMR equations.

Question 13

How many calories should I eat based on my BMR?

Accepted Answer

Your BMR alone is not enough to set a calorie target — you need your TDEE (BMR × activity factor). For weight loss, eat 250-750 calories below your TDEE. For maintenance, eat at your TDEE. For muscle gain, eat 250-500 calories above your TDEE. Never go below your BMR for extended periods. For example, if your BMR is 1,500 and your TDEE is 2,300, a moderate weight loss target would be around 1,800 calories per day.

Question 14

Can eating more protein increase my metabolism?

Accepted Answer

Yes, modestly. Protein has the highest thermic effect of food (TEF) at 20-30%, meaning your body burns 20-30% of protein calories just digesting it, compared to 5-10% for carbs and 0-3% for fats. Eating 150g of protein per day can increase your daily calorie burn by 60-100 calories from TEF alone. Protein also helps preserve muscle mass during weight loss, which protects your long-term BMR.

Scenario	Per Week	Daily Calories
Aggressive	-0.75kg/wk	1,721kcal
Moderate	-0.50kg/wk	1,996kcal
Slow	-0.25kg/wk	2,271kcal
Maintain	0kg/wk	2,546kcal
Slow	+0.25kg/wk	2,821kcal
Moderate	+0.50kg/wk	3,096kcal
Aggressive	+0.75kg/wk	3,371kcal

Factor	Effect on BMR
Muscle Mass	More muscle = higher BMR. Muscle tissue burns ~6 kcal/lb/day at rest vs ~2 kcal/lb for fat.
Age	BMR decreases ~1-2% per decade after age 20, largely due to muscle loss (sarcopenia).
Gender	Men typically have 5-10% higher BMR due to greater muscle mass and lower body fat.
Body Size	Taller and heavier individuals burn more calories at rest — more tissue to maintain.
Genetics	Can account for up to 10% variation between individuals with similar body composition.
Hormones	Thyroid hormones (T3, T4) directly regulate metabolic rate. Conditions like hypothyroidism lower BMR.
Climate	Cold environments increase BMR as the body burns extra energy to maintain core temperature.

Activity Level	Factor	Description
Sedentary	1.2	Desk job, little or no exercise
Lightly Active	1.375	Light exercise 1-3 days per week
Moderately Active	1.55	Moderate exercise 3-5 days per week
Very Active	1.725	Hard exercise 6-7 days per week
Extra Active	1.9	Very hard daily exercise or physical job

BMR Calculator

Calorie Goals

Visual Comparison

Nutrition Breakdown

Maintain Weight Daily Distribution

Protein

Fats

Carbs

Formula Comparison

Weight Change Impact

What is BMR (Basal Metabolic Rate)?

How to Calculate BMR

BMR Calculation Formulas

Mifflin-St Jeor Equation

Katch-McArdle Formula

BMR vs TDEE: What's the Difference?

BMR (Resting)

TDEE (Total)

Factors That Affect Your BMR

Activity Level Multipliers

How to Use BMR for Weight Loss

Slow (0.25 kg/week)

Moderate (0.5 kg/week)

Aggressive (0.75 kg/week)

How to Increase Your BMR

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Important Disclaimer

Frequently Asked Questions

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