What is Basal Metabolic Rate (BMR)?
Basal Metabolic Rate (BMR) is the minimum amount of energy your body needs to maintain basic, life-sustaining functions while at rest. These functions include breathing, circulation, cell production, nutrient processing, protein synthesis, and the transport of ions across membranes. Essentially, it's the number of calories your body burns when you're completely inactive, like when you're sleeping.
Understanding your BMR is a crucial first step in managing your weight and optimizing your health. It helps you determine how many calories you should consume daily to either maintain, lose, or gain weight. Your BMR is influenced by several factors, including age, sex, weight, height, and body composition.
Factors Affecting BMR:
- Age: BMR generally decreases as people get older.
- Sex: Men typically have a higher BMR than women due to generally higher muscle mass.
- Weight: A heavier body requires more energy to maintain.
- Height: Taller individuals tend to have a higher BMR.
- Body Composition: Muscle tissue burns more calories at rest than fat tissue. The more muscle you have, the higher your BMR.
- Genetics: Individual genetic makeup plays a role in metabolic rate.
- Hormone Levels: Thyroid hormones, in particular, significantly impact metabolism.
How is BMR Calculated?
There are several formulas to estimate BMR. The most commonly used are the Harris-Benedict Equation (original and revised) and the Mifflin-St Jeor Equation. The Mifflin-St Jeor equation is generally considered more accurate for most people today.
This calculator uses the 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
Once you have your BMR, you can then calculate your Total Daily Energy Expenditure (TDEE) by multiplying your BMR by an activity factor that corresponds to your lifestyle. This calculator focuses solely on estimating your BMR.