The Basal Metabolic Rate (BMR) is the number of calories your body needs to perform basic life-sustaining functions while at rest. This includes breathing, circulating blood, regulating body temperature, and cell production. Understanding your BMR is crucial for managing your weight, as it represents the minimum calorie intake required to keep your body running.
Body fat percentage is a measure used to express how much of your total body weight is composed of fat. It is generally considered a more accurate indicator of health and fitness than Body Mass Index (BMI) alone, as it differentiates between lean body mass (muscles, bones, organs) and fat mass.
How is BMR Calculated?
Several formulas exist to estimate BMR. The most commonly used are the Harris-Benedict Equation and the Mifflin-St Jeor Equation. For this calculator, we use the Mifflin-St Jeor Equation, which is generally considered more accurate for most individuals.
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
Calculating Lean Body Mass and Fat Mass
Once your BMR is calculated, you can use your body fat percentage to determine your lean body mass and fat mass.
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Lean Body Mass (LBM): This is your total weight minus the weight of your fat.
LBM = Total Weight (kg) × (1 – (Body Fat % / 100)) -
Fat Mass: This is the portion of your total weight that is fat.
Fat Mass = Total Weight (kg) × (Body Fat % / 100)
Why This Matters
Knowing your BMR helps you understand your fundamental calorie needs. Combined with your body composition (lean mass vs. fat mass), it provides a more holistic view of your health. For example, individuals with higher lean muscle mass typically have a higher BMR than those with a similar weight but a higher body fat percentage. This information is valuable for:
- Weight management goals (loss, gain, or maintenance).
- Designing effective exercise and nutrition plans.
- Tracking progress over time.
- Understanding your overall metabolic health.
Disclaimer: This calculator provides an estimation. For personalized health and fitness advice, please consult with a qualified healthcare professional or a certified fitness expert.