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 a week)
Extra Active (very hard exercise/sports & physical job or 2x training)
What is Basal Metabolic Rate (BMR) and Active BMR?
Basal Metabolic Rate (BMR) is the minimum number of calories your body needs to perform basic life-sustaining functions while at rest. This includes breathing, circulating blood, cell production, and regulating body temperature. Essentially, it's the energy your body burns just to keep you alive, even if you were to do nothing all day.
Your BMR is influenced by several factors, including your age, gender, weight, and height. Generally, muscle tissue burns more calories than fat tissue, so individuals with more muscle mass tend to have a higher BMR.
Active BMR (often referred to as Total Daily Energy Expenditure or TDEE) takes your BMR and factors in your daily physical activity level. It represents the total number of calories you burn in a 24-hour period, considering both your resting metabolic rate and the energy you expend through all forms of physical activity, from walking to intense workouts.
To calculate your Active BMR, we first estimate your BMR using the Mifflin-St Jeor equation, which is widely considered one of the most accurate methods:
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 your BMR is calculated, it's multiplied by an activity factor to estimate your Active BMR (TDEE):
Sedentary: BMR × 1.2
Lightly Active: BMR × 1.375
Moderately Active: BMR × 1.55
Very Active: BMR × 1.725
Extra Active: BMR × 1.9
Understanding your Active BMR is crucial for managing your weight. If your calorie intake matches your Active BMR, you're likely to maintain your current weight. Consuming fewer calories than your Active BMR can lead to weight loss, while consuming more can lead to weight gain.
function calculateActiveBMR() {
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 resultDiv = document.getElementById("result");
var bmr = 0;
// Input validation
if (isNaN(weight) || weight <= 0 ||
isNaN(height) || height <= 0 ||
isNaN(age) || age <= 0) {
resultDiv.innerHTML = "Please enter valid positive numbers for weight, height, and age.";
return;
}
// Calculate BMR using Mifflin-St Jeor equation
if (gender === "male") {
bmr = (10 * weight) + (6.25 * height) – (5 * age) + 5;
} else { // female
bmr = (10 * weight) + (6.25 * height) – (5 * age) – 161;
}
var activityMultiplier = 0;
switch (activityLevel) {
case "sedentary":
activityMultiplier = 1.2;
break;
case "lightly_active":
activityMultiplier = 1.375;
break;
case "moderately_active":
activityMultiplier = 1.55;
break;
case "very_active":
activityMultiplier = 1.725;
break;
case "extra_active":
activityMultiplier = 1.9;
break;
default:
resultDiv.innerHTML = "Please select an activity level.";
return;
}
var activeBMR = bmr * activityMultiplier;
resultDiv.innerHTML = "Your estimated Active BMR (TDEE) is: " + activeBMR.toFixed(2) + " calories per day.";
}