Your Basal Metabolic Rate (BMR) is the minimum number of calories your body needs to perform essential life-sustaining functions at rest. These functions include breathing, circulating blood, regulating body temperature, and cell production. Essentially, it's the energy your body burns just to keep you alive and functioning when you're completely at rest, like when you're sleeping.
Understanding your BMR is a fundamental step in managing your weight and overall health. It helps you determine how many calories you need to consume daily to maintain, lose, or gain weight effectively. While your BMR represents the calories burned at complete rest, your Total Daily Energy Expenditure (TDEE) includes the calories you burn through physical activity and the thermic effect of food.
How is BMR Calculated?
The most common and widely accepted formulas for calculating BMR are the Harris-Benedict Equation and the Mifflin-St Jeor Equation. The Mifflin-St Jeor Equation is generally considered more accurate for most people.
Mifflin-St Jeor Equation:
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
Harris-Benedict Equation (Revised):
For Men: BMR = (13.397 × weight in kg) + (4.799 × height in cm) – (5.677 × age in years) + 88.362
For Women: BMR = (9.247 × weight in kg) + (3.098 × height in cm) – (4.330 × age in years) + 447.593
This calculator uses the Mifflin-St Jeor Equation for its calculation.
Factors Influencing BMR:
Body Composition: Muscle tissue burns more calories at rest than fat tissue. Therefore, individuals with more muscle mass tend to have a higher BMR.
Age: BMR generally decreases with age, as muscle mass tends to decline and metabolic processes slow down.
Sex: Men typically have a higher BMR than women due to generally higher muscle mass and body size.
Genetics: Your inherited genes play a role in determining your metabolic rate.
Hormones: Thyroid hormones, in particular, significantly influence BMR.
Body Size: Larger individuals generally have a higher BMR.
Knowing your BMR is a powerful tool for understanding your body's energy needs. It's the foundation upon which you can build a personalized approach to nutrition and fitness.