Basal Metabolic Rate Calculator Metric

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Basal Metabolic Rate (BMR) Calculator (Metric)

Your Basal Metabolic Rate (BMR) is the number of calories your body needs to perform basic life-sustaining functions while at rest. This includes breathing, circulation, cell production, and more. Understanding your BMR is a crucial first step in managing your weight and optimizing your diet for your specific needs.

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.calculator-container { font-family: sans-serif; max-width: 500px; margin: 20px auto; padding: 20px; border: 1px solid #ccc; border-radius: 8px; box-shadow: 0 2px 4px rgba(0,0,0,0.1); } .input-section { margin-bottom: 15px; } .input-section label { display: block; margin-bottom: 5px; font-weight: bold; } .input-section input[type="number"], .input-section select { width: calc(100% – 12px); padding: 8px; border: 1px solid #ccc; border-radius: 4px; box-sizing: border-box; /* Include padding and border in the element's total width and height */ } .calculator-container button { background-color: #4CAF50; color: white; padding: 10px 15px; border: none; border-radius: 4px; cursor: pointer; font-size: 16px; margin-top: 10px; } .calculator-container button:hover { background-color: #45a049; } #result { margin-top: 20px; padding: 15px; background-color: #f9f9f9; border: 1px solid #eee; border-radius: 4px; text-align: center; font-size: 18px; font-weight: bold; } function calculateBMR() { var weight = parseFloat(document.getElementById("weight").value); var height = parseFloat(document.getElementById("height").value); var age = parseFloat(document.getElementById("age").value); var gender = document.getElementById("gender").value; var resultDiv = document.getElementById("result"); if (isNaN(weight) || isNaN(height) || isNaN(age) || weight <= 0 || height <= 0 || age <= 0) { resultDiv.innerHTML = "Please enter valid positive numbers for weight, height, and age."; return; } var bmr = 0; // Mifflin-St Jeor Equation (considered more accurate) if (gender === "male") { bmr = (10 * weight) + (6.25 * height) – (5 * age) + 5; } else { // female bmr = (10 * weight) + (6.25 * height) – (5 * age) – 161; } resultDiv.innerHTML = "Your estimated Basal Metabolic Rate (BMR) is: " + bmr.toFixed(2) + " calories/day"; }

Understanding Your Basal Metabolic Rate (BMR)

Your Basal Metabolic Rate (BMR) represents the minimum number of calories your body requires to maintain essential physiological functions when it's in a state of complete rest. Think of it as the energy your body burns just to keep you alive – to power your brain, heart, lungs, kidneys, and other vital organs. This calculation does not account for any physical activity or the thermic effect of food (the calories burned digesting food).

Factors Influencing BMR:

  • Body Composition: Muscle tissue burns more calories at rest than fat tissue. Therefore, individuals with higher muscle mass tend to have a higher BMR.
  • Age: BMR generally decreases with age, partly due to a natural decline in muscle mass and metabolic rate.
  • Sex: Men typically have a higher BMR than women due to generally larger body size and higher muscle mass.
  • Genetics: Your inherited traits can play a role in how efficiently your body uses energy.
  • Body Size and Shape: Larger individuals generally have a higher BMR because they have more tissue to maintain.

How the Mifflin-St Jeor Equation Works:

The Mifflin-St Jeor equation is a widely accepted and generally accurate formula for estimating BMR. It uses your weight, height, age, and sex to provide a personalized calorie estimate.

  • 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

Using Your BMR:

Once you have your BMR, you can use it as a baseline for calculating your total daily energy expenditure (TDEE). To do this, you multiply your BMR by an activity factor that reflects your lifestyle (e.g., sedentary, lightly active, moderately active, very active). This TDEE then informs how many calories you need to consume daily to maintain, lose, or gain weight.

Example Calculation:

Let's consider a 30-year-old male who weighs 70 kg and is 175 cm tall.

Using the Mifflin-St Jeor equation for men:

BMR = (10 × 70) + (6.25 × 175) – (5 × 30) + 5

BMR = 700 + 1093.75 – 150 + 5

BMR = 1648.75 calories per day.

This means this individual needs approximately 1648.75 calories per day just to maintain basic bodily functions at rest.

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