Understanding BMR
Your Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest just to maintain basic life functions: breathing, circulation, cell production, and temperature regulation. It accounts for 60-75% of your total daily calorie burn.
Why BMR Matters
- Weight Management: Knowing your BMR helps you understand your baseline calorie needs
- Goal Setting: To lose weight, you need to eat below your total daily energy expenditure
- Health Insights: A very low BMR may indicate thyroid issues; a high BMR means more muscle mass
- Nutrition Planning: Helps dietitians create personalized meal plans
The Mifflin-St Jeor Formula
We use the Mifflin-St Jeor equation, considered the most accurate BMR formula:
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
Activity Level Multipliers
To estimate your total daily calories, multiply your BMR by your activity level:
- Sedentary: BMR × 1.2 (desk job, little 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 (hard exercise 6-7 days/week)
- Extra Active: BMR × 1.9 (very hard exercise, physical labor)
Factors That Affect BMR
Muscle Mass: Muscle burns more calories than fat, even at rest
Age: BMR decreases about 2% per decade after age 30
Genetics: Some people naturally have faster or slower metabolisms
Thyroid Function: An overactive thyroid increases BMR; underactive decreases it
Gender: Men typically have 5-10% higher BMR than women due to more muscle mass
How to Use This Information
To maintain your current weight: Eat your TDEE (total daily energy expenditure = BMR × activity level)
To lose weight: Create a calorie deficit of 300-500 calories per day (about 0.5-1 lb per week)
To gain weight: Add 300-500 calories per day above your TDEE
Important Notes
- BMR calculators provide estimates - individual variations exist
- Extremely low calorie intake (< 1,200 for women, < 1,500 for men) can slow metabolism
- Consult a healthcare provider before starting any significant diet or exercise program
- Focus on sustainable, gradual changes rather than extreme restriction