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Understanding Your Basal Metabolic Rate

How to calculate Basal Metabolic Rate (BMR)?

Basal Metabolic Rate (BMR) is the number of calories your body needs to accomplish its most basic (basal) life-sustaining functions. This calculator uses the Mifflin-St Jeor Equation, which is widely recognized for its accuracy.

The Mifflin-St Jeor Equation is:

For Men: BMR = (10 × weight_kg) + (6.25 × height_cm) - (5 × age_years) + 5

For Women: BMR = (10 × weight_kg) + (6.25 × height_cm) - (5 × age_years) - 161

Using the BMR calculator: an example

Let's calculate the BMR for a 35-year-old female who weighs 65 kg and is 160 cm tall.

Step-by-step calculation:

• Given: Age = 35 years, Weight = 65 kg, Height = 160 cm, Sex = Female
• Formula for Women: BMR = (10 × weight_kg) + (6.25 × height_cm) - (5 × age_years) - 161
• Substitute values: BMR = (10 × 65) + (6.25 × 160) - (5 × 35) - 161
• Calculate: BMR = 650 + 1000 - 175 - 161
• Result: BMR = 1314 Calories/Day

Factors Affecting BMR

• Age: BMR decreases with age due to loss of muscle mass.
• Sex: Men generally have higher BMRs than women due to a higher percentage of muscle mass.
• Weight & Height: Larger and taller individuals tend to have higher BMRs.
• Body Composition: Muscle burns more calories at rest than fat, so a higher muscle-to-fat ratio increases BMR.
• Genetics: Genetic factors can influence your BMR.
• Thyroid Hormones: Thyroid hormones regulate metabolism; imbalances can affect BMR.

Frequently Asked Questions

1. What is the difference between BMR and RMR?
   BMR (Basal Metabolic Rate) is measured under very strict conditions (e.g., after 12 hours of fasting and 8 hours of sleep), representing the minimum energy needed for basic functions. RMR (Resting Metabolic Rate) is measured under less strict conditions and is often used interchangeably with BMR, as the difference is usually negligible.
2. Why is BMR important?
   Knowing your BMR can help you understand your daily caloric needs. It's a foundational number for planning weight management strategies, as it tells you how many calories your body burns just to exist, before any activity.
3. Can I increase my BMR?
   Yes, primarily by increasing your muscle mass. Muscle tissue burns more calories at rest than fat tissue. Regular strength training can help build muscle, thereby increasing your BMR.
4. Is this calculator accurate?
   This calculator uses the Mifflin-St Jeor Equation, which is considered one of the most accurate formulas for estimating BMR. However, it provides an estimate, and individual results may vary based on genetics, health conditions, and other factors.