.calculator-widget {
font-family: sans-serif;
border: 1px solid #ccc;
padding: 20px;
border-radius: 8px;
max-width: 400px;
margin: 20px auto;
box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}
.calculator-input .input-row {
margin-bottom: 15px;
display: flex;
align-items: center;
justify-content: space-between;
}
.calculator-input label {
margin-right: 10px;
font-weight: bold;
flex-basis: 50%;
}
.calculator-input input[type="number"],
.calculator-input select {
padding: 8px;
border: 1px solid #ccc;
border-radius: 4px;
width: 50%;
box-sizing: border-box;
}
.calculator-input button {
background-color: #4CAF50;
color: white;
padding: 10px 15px;
border: none;
border-radius: 4px;
cursor: pointer;
width: 100%;
margin-top: 10px;
font-size: 16px;
}
.calculator-input button:hover {
background-color: #45a049;
}
.calculator-result {
margin-top: 20px;
padding: 15px;
border: 1px solid #e0e0e0;
border-radius: 4px;
background-color: #f9f9f9;
text-align: center;
font-size: 1.1em;
min-height: 50px;
display: flex;
align-items: center;
justify-content: center;
}
function calculateWeightLoss() {
var age = parseFloat(document.getElementById("age").value);
var weight = parseFloat(document.getElementById("weight").value);
var height = parseFloat(document.getElementById("height").value);
var gender = document.getElementById("gender").value;
var duration = parseFloat(document.getElementById("duration").value);
var intensity = document.getElementById("intensity").value;
var resultDiv = document.getElementById("result");
resultDiv.innerHTML = "; // Clear previous results
if (isNaN(age) || isNaN(weight) || isNaN(height) || isNaN(duration) || age <= 0 || weight <= 0 || height <= 0 || duration <= 0) {
resultDiv.innerHTML = 'Please enter valid positive numbers for all fields.';
return;
}
// 1. Calculate Basal Metabolic Rate (BMR) using Mifflin-St Jeor Equation
var bmr;
if (gender === "male") {
bmr = (10 * weight) + (6.25 * height) – (5 * age) + 5;
} else { // female
bmr = (10 * weight) + (6.25 * height) – (5 * age) – 161;
}
// 2. Calculate Total Daily Energy Expenditure (TDEE)
// This is a simplified approach. A more accurate calculation would involve activity factors.
// For simplicity, we'll assume a baseline activity level for TDEE calculation and then add exercise.
var tdee;
var activityFactor = 1.375; // Lightly active (example factor)
tdee = bmr * activityFactor;
// 3. Estimate Calories Burned During Exercise
// This is a rough estimation based on MET values (Metabolic Equivalents)
// MET values are approximate and vary greatly with individual effort and fitness level.
var metValue;
if (intensity === "low") {
metValue = 3.5; // e.g., walking slowly
} else if (intensity === "moderate") {
metValue = 7.0; // e.g., brisk walking, jogging
} else { // high
metValue = 10.0; // e.g., running, high-intensity interval training
}
// Calories burned per minute = (MET * 3.5 * weight_in_kg) / 200
var caloriesBurnedPerMinute = (metValue * 3.5 * weight) / 200;
var totalCaloriesBurnedFromExercise = caloriesBurnedPerMinute * duration;
// 4. Calculate Net Calorie Deficit
// We need to consider the calories burned from exercise ON TOP of the TDEE.
// For weight loss calculation, we look at the total deficit.
// A common deficit for 1 lb of fat loss is ~3500 calories.
var totalCaloriesExpendedDaily = tdee + totalCaloriesBurnedFromExercise; // This is an oversimplification. TDEE already includes basal + activity. We are adding exercise to basal here.
// A more accurate approach would be:
// TDEE_with_exercise = BMR * ActivityFactor (excluding exercise) + CaloriesBurnedFromExercise
// For a simplified calculator, we'll consider the deficit as:
// calories_deficit = TDEE – calories_consumed.
// Since we don't have calories consumed, we'll focus on calories burned relative to BMR.
// Let's reframe: How many calories can be burned relative to resting metabolism over the exercise duration?
// We can estimate weekly deficit if we assume this exercise is done daily.
var estimatedWeeklyCaloriesBurned = totalCaloriesBurnedFromExercise * 7;
var estimatedWeightLossPounds = estimatedWeeklyCaloriesBurned / 3500; // 1 lb fat approx 3500 calories
var resultHTML = "Estimated weekly weight loss:
" + estimatedWeightLossPounds.toFixed(2) + " lbs";
resultHTML += "Total calories burned during exercise session:
" + totalCaloriesBurnedFromExercise.toFixed(2) + " kcal";
resultDiv.innerHTML = resultHTML;
}
Understanding Heart Rate for Weight Loss
Achieving weight loss through exercise involves creating a calorie deficit – burning more calories than you consume. Your heart rate plays a crucial role in determining the intensity of your workouts and, consequently, the number of calories you burn. Different heart rate zones target different physiological responses, and understanding them can help you optimize your exercise routine for fat loss.
Heart Rate Zones and Their Impact on Weight Loss
While a generic calorie burn from exercise is useful, targeting specific heart rate zones can be more effective for fat metabolism. The intensity of your exercise, often measured by your heart rate, directly correlates with the type of fuel your body primarily uses.
- Low Intensity (Fat Burning Zone): Typically around 50-65% of your Maximum Heart Rate (MHR). In this zone, your body preferentially burns fat for fuel. It's sustainable for longer durations and is excellent for building endurance and improving cardiovascular health without excessive strain.
- Moderate Intensity (Cardio Zone): Around 65-75% of your MHR. This zone increases your heart rate and breathing significantly, making your body burn a higher total number of calories, including a good mix of carbohydrates and fats. It's a sweet spot for improving cardiovascular fitness and promoting weight loss.
- High Intensity (Aerobic/Anaerobic Zone): Above 75% of your MHR. While this zone burns the most calories per minute and is very effective for improving athletic performance and boosting metabolism (EPOC – Excess Post-exercise Oxygen Consumption), it relies more on carbohydrates for fuel and can be challenging to sustain for long periods.
How This Calculator Works
This calculator provides an estimation of the potential weight loss based on your personal metrics (age, weight, height, gender), exercise duration, and perceived intensity level.
- BMR (Basal Metabolic Rate): We first estimate your BMR using the Mifflin-St Jeor equation, which is considered one of the most accurate formulas for calculating the calories your body burns at rest.
- Calories Burned During Exercise: Using your selected intensity level, we assign an approximate MET (Metabolic Equivalent of Task) value. This value, along with your weight, duration, and the MET value, helps estimate the calories you burn during your workout session.
- Estimated Weight Loss: A common benchmark in weight loss is that approximately 3500 calories equate to one pound of fat. By calculating the total estimated calories burned from your exercise session and extrapolating it over a week (assuming daily exercise), the calculator provides an estimated weekly weight loss in pounds.
Important Note: This calculator is an estimation tool. Actual weight loss depends on many factors, including your overall daily calorie intake, metabolism, hormonal factors, consistency of exercise, and individual physiological responses. For personalized advice and a comprehensive weight loss plan, consult with a healthcare professional or a certified fitness trainer.