Understanding your Basal Metabolic Rate (BMR) is key to managing your weight, optimizing your fitness goals, and ensuring your body gets the right amount of energy. BMR represents the number of calories your body burns at rest to maintain basic functions like breathing, circulation, and digestion.

By calculating your BMR, you can determine how many calories you need to maintain, lose, or gain weight. This guide will explain what BMR is, how to calculate it, and how to use it effectively for weight management.

basal metabolic rate

What Is Basal Metabolic Rate (BMR)?

BMR is the minimum number of calories your body requires to function while at complete rest. This includes essential bodily processes such as:

  • Breathing
  • Circulating blood
  • Regulating body temperature
  • Cell production
  • Organ function

Since BMR accounts for 60-75% of your total daily energy expenditure (TDEE), knowing your BMR can help you make informed dietary and fitness decisions.

How to Calculate Your BMR

There are different equations to calculate BMR, but the most widely used is the Mifflin-St Jeor Equation due to its accuracy.

Mifflin-St Jeor Equation

For men:
BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age) + 5

For women:
BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age) – 161

Example Calculation

Let’s say a 35-year-old woman weighs 70 kg (154 lbs) and is 165 cm (5’5”) tall.

BMR = (10 × 70) + (6.25 × 165) – (5 × 35) – 161
BMR = 700 + 1031.25 – 175 – 161
BMR = 1395.25 calories/day

This means that if she were at complete rest for 24 hours, her body would burn around 1,395 calories just to keep her alive.

Using Your BMR to Determine Daily Calorie Needs

Since most people are not at complete rest all day, you must adjust your BMR based on your activity level to estimate your Total Daily Energy Expenditure (TDEE).

TDEE Calculation (Harris-Benedict Equation)

Multiply your BMR by your activity level:

Activity Level Multiplier Description
Sedentary BMR × 1.2 Little to no exercise
Lightly active BMR × 1.375 Light exercise 1-3 days/week
Moderately active BMR × 1.55 Moderate exercise 3-5 days/week
Very active BMR × 1.725 Intense exercise 6-7 days/week
Super active BMR × 1.9 Intense daily exercise or physical job

Example TDEE Calculation

Using the previous example (BMR = 1,395 calories/day), if the woman is moderately active (1.55 multiplier):

TDEE = 1,395 × 1.55 = 2,162 calories/day

This means she burns around 2,162 calories daily with her normal activity level.

How to Use Your BMR for Weight Management

Once you know your TDEE, you can adjust your calorie intake based on your goals:

1. For Weight Maintenance

Consume calories equal to TDEE to maintain your current weight.

2. For Weight Loss

  • Create a caloric deficit by consuming fewer calories than your TDEE.
  • A 500-calorie deficit per day results in about one pound of fat loss per week.
  • Example: If TDEE is 2,162 calories, a weight loss intake could be 1,662 calories/day.

3. For Muscle Gain

  • Consume calories above TDEE to build muscle.
  • A 300-500 calorie surplus is recommended for lean muscle gain.
  • Example: If TDEE is 2,162 calories, aim for 2,462+ calories/day.

Factors That Affect Your BMR

1. Age

BMR decreases with age because muscle mass declines and metabolism slows.

2. Muscle Mass

More muscle mass increases BMR since muscle requires more energy than fat.

3. Gender

Men generally have higher BMR than women due to greater muscle mass.

4. Genetics

Some individuals naturally have a faster or slower metabolism.

5. Diet and Nutrition

  • Protein intake helps preserve muscle mass and maintain a healthy BMR.
  • Severe calorie restriction can slow metabolism over time.

6. Hormones

Thyroid function and other hormones impact metabolism and energy expenditure.

Using a BMR Calculator

Instead of manually calculating BMR, you can use an online BMR calculator for quick results:

Simply enter your age, gender, weight, height, and activity level to get your estimated BMR and TDEE.

Conclusion

Knowing your Basal Metabolic Rate (BMR) is essential for effective weight management, fitness progress, and overall health. By calculating your BMR and adjusting calorie intake based on your activity level, you can:

  • Maintain, lose, or gain weight effectively.
  • Optimize energy levels and nutrition.
  • Make informed decisions about your diet and exercise routine.

Use this guide to calculate your BMR and TDEE, and start making smarter choices about your health and fitness today.

Last Updated on July 3, 2025