Calculator for Metabolic Rate

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Male Female
Sedentary (little or no exercise) Lightly Active (light exercise/sports 1-3 days/week) Moderately Active (moderate exercise/sports 3-5 days/week) Very Active (hard exercise/sports 6-7 days/week) Extra Active (very hard exercise/sports & physical job)
function calculateMetabolicRate() { var weight = document.getElementById("weight").value; var height = document.getElementById("height").value; var age = document.getElementById("age").value; var gender = document.getElementById("gender").value; var activityLevel = document.getElementById("activityLevel").value; var weightNum = parseFloat(weight); var heightNum = parseFloat(height); var ageNum = parseFloat(age); var bmr = 0; if (isNaN(weightNum) || isNaN(heightNum) || isNaN(ageNum) || weightNum <= 0 || heightNum <= 0 || ageNum <= 0) { document.getElementById("result").innerHTML = "Please enter valid positive numbers for weight, height, and age."; return; } if (gender === "male") { // Mifflin-St Jeor Equation for Men bmr = (10 * weightNum) + (6.25 * heightNum) – (5 * ageNum) + 5; } else { // Mifflin-St Jeor Equation for Women bmr = (10 * weightNum) + (6.25 * heightNum) – (5 * ageNum) – 161; } var tdee = 0; switch (activityLevel) { case "sedentary": tdee = bmr * 1.2; break; case "lightlyActive": tdee = bmr * 1.375; break; case "moderatelyActive": tdee = bmr * 1.55; break; case "veryActive": tdee = bmr * 1.725; break; case "extraActive": tdee = bmr * 1.9; break; } document.getElementById("result").innerHTML = "

Your Results

" + "Basal Metabolic Rate (BMR): " + bmr.toFixed(2) + " kcal/day" + "Total Daily Energy Expenditure (TDEE): " + tdee.toFixed(2) + " kcal/day"; }

Understanding Your Metabolic Rate

Your metabolic rate is the rate at which your body burns calories to perform basic life-sustaining functions. It's a fundamental aspect of your overall health and plays a crucial role in weight management. There are two key components to understand: Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE).

Basal Metabolic Rate (BMR)

BMR represents the number of calories your body needs to function at rest. This includes vital processes like breathing, circulation, cell production, and nutrient processing. It's the energy your body expends even if you were to sleep all day.

The Mifflin-St Jeor equation is a widely accepted method for estimating BMR. It takes into account your weight, height, age, and sex, as these factors significantly influence your resting energy needs.

  • 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

Total Daily Energy Expenditure (TDEE)

TDEE is a more comprehensive measure of your calorie needs. It's your BMR multiplied by an activity factor that reflects your lifestyle. The activity factor accounts for the calories burned through daily activities, exercise, and thermic effect of food.

The activity factors typically used are:

  • Sedentary: Little or no exercise (BMR x 1.2)
  • Lightly Active: Light exercise/sports 1-3 days/week (BMR x 1.375)
  • Moderately Active: Moderate exercise/sports 3-5 days/week (BMR x 1.55)
  • Very Active: Hard exercise/sports 6-7 days/week (BMR x 1.725)
  • Extra Active: Very hard exercise/sports & physical job (BMR x 1.9)

Why is This Important?

Understanding your metabolic rate can be invaluable for achieving your health and fitness goals. Whether you aim to lose weight, gain muscle, or maintain your current physique, knowing your calorie expenditure is a critical starting point. By adjusting your calorie intake to align with your TDEE, you can effectively manage your weight.

Example Calculation:

Let's consider Sarah, a 30-year-old woman who weighs 65 kg, is 165 cm tall, and has a moderately active lifestyle.

1. Calculate BMR:

BMR = (10 × 65) + (6.25 × 165) – (5 × 30) – 161

BMR = 650 + 1031.25 – 150 – 161

BMR = 1370.25 kcal/day

2. Calculate TDEE (Moderately Active):

TDEE = BMR × 1.55

TDEE = 1370.25 × 1.55

TDEE = 2123.89 kcal/day

Therefore, Sarah needs approximately 2123.89 calories per day to maintain her current weight. To lose weight, she would need to consume fewer calories than this, and to gain weight, she would need to consume more.

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