How To Calculate BMR And TDEE Using Miffin-St Jeor Equation

Starting a fitness journey means you need to know how much energy your body needs. Your Total Daily Energy Expenditure (TDEE) shows the total calories your body requires each day, accounting for when you’re resting and active.

The Mifflin-St Jeor Equation helps figure this out, especially by looking at Basal Metabolic Rate (BMR). In this guide, we’ll explain the process step by step and give two examples to make it easier to understand.

How to calculate BMR and Tdee

What is TDEE?

Total Daily Energy Expenditure (TDEE) is the total number of calories your body needs in a day. It encompasses the calories burnt while at rest (BMR) and during various activities like exercise, work, and daily tasks.

Understanding Mifflin-St Jeor Equation:

The Mifflin-St Jeor Equation is a straightforward method for calculating TDEE, starting with the determination of Basal Metabolic Rate (BMR):

Step 1: Calculating Basal Metabolic Rate (BMR)

The BMR calculation is a little different for men and women:

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

This step gives you the calories your body requires at rest, without considering any additional physical activity.

Step 2: Activity Level Exploration

To calculate your TDEE, you need to factor in your activity level. Here are the activity factors for different levels:

  1. Sedentary (little or no exercise): Multiply BMR by 1.2.
  2. Lightly active (light exercise or sports 1-3 days a week): Multiply BMR by 1.375.
  3. Moderately active (moderate exercise or sports 3-5 days a week): Multiply BMR by 1.55.
  4. Very active (hard exercise or sports 6-7 days a week): Multiply BMR by 1.725.
  5. Extremely active (very hard exercise, physically demanding job, or training twice a day): Multiply BMR by 1.9.

Step 3: TDEE Calculation

Multiply your BMR by the activity factor that corresponds to your lifestyle.

TDEE = BMR×Activity Factor

Example Calculations:

Let’s put this into practice with two examples.

Example 1: Sarah

Sarah is a 25-year-old woman weighing 60 kg, standing at 160 cm. She engages in moderate exercise 3-5 days a week.

BMR = (10×60)+(6.25×160)−(5×25)−161
BMR = 1314

Activity Factor: 1.55

TDEE = BMR×Activity Factor

Sarah’s estimated TDEE is approximately,
TDEE = (1314)×(1.55) ≈ 2036.7 calories.

Example 2: James

James is a 30-year-old man weighing 80 kg, standing at 175 cm. He has a very active lifestyle, engaging in hard exercise 6-7 days a week.

BMR = (10×80)+(6.25×175)−(5×30)+5
BMR = 1748.75 (we round it to 1749)

Activity Factor: 1.725

TDEE = BMR×Activity Factor

James’s estimated TDEE is approximately,
TDEE = (1749)×(1.725) ≈ 3017 calories.

If doing the math on your own feels like too much work, there’s a simpler way! You can use an online tool called a TDEE calculator. One of the most popular and accurate ones is on tdee-calculator.net. This tool makes it super easy to find out how many calories your body needs every day without having to do any complicated calculations. Just input some basic information, and it does the job for you!

Conclusion:

Mastering TDEE calculation with the Mifflin-St Jeor Equation and BMR is akin to having a personalized nutrition guide. Apply this knowledge to tailor your diet and exercise routine for a healthier lifestyle. These calculations provide a starting point, and adjustments can be made based on individual progress and goals. Enjoy the process of becoming the best version of yourself!

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