function calculateMacros() {
var gender = document.querySelector('input[name="gender"]:checked').value;
var age = parseFloat(document.getElementById("age").value);
var weight = parseFloat(document.getElementById("weight").value); // kg
var height = parseFloat(document.getElementById("height").value); // cm
var activityLevel = document.getElementById("activityLevel").value;
var goal = document.getElementById("goal").value;
// Input validation
if (isNaN(age) || age <= 0 || isNaN(weight) || weight <= 0 || isNaN(height) || height <= 0) {
alert("Please enter valid positive numbers for Age, Weight, and Height.");
return;
}
var bmr;
// 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 activityFactor;
switch (activityLevel) {
case "sedentary":
activityFactor = 1.2;
break;
case "lightlyActive":
activityFactor = 1.375;
break;
case "moderatelyActive":
activityFactor = 1.55;
break;
case "veryActive":
activityFactor = 1.725;
break;
case "extremelyActive":
activityFactor = 1.9;
break;
default:
activityFactor = 1.2; // Default to sedentary
}
var tdee = bmr * activityFactor;
var adjustedCalories = tdee;
switch (goal) {
case "maintain":
adjustedCalories = tdee;
break;
case "mildLoss":
adjustedCalories = tdee – 250;
break;
case "moderateLoss":
adjustedCalories = tdee – 500;
break;
case "extremeLoss":
adjustedCalories = tdee – 750;
break;
case "mildGain":
adjustedCalories = tdee + 250;
break;
case "moderateGain":
adjustedCalories = tdee + 500;
break;
case "extremeGain":
adjustedCalories = tdee + 750;
break;
}
// Ensure calories don't go too low for safety
if (adjustedCalories < 1000) {
adjustedCalories = 1000; // Minimum safe calorie intake
}
// Macronutrient split percentages (example values)
var proteinPercentage = 0.30; // 30% of calories from protein
var fatPercentage = 0.25; // 25% of calories from fat
var carbPercentage = 1 – proteinPercentage – fatPercentage; // Remaining for carbs
// Calculate calories from each macro
var proteinCalories = adjustedCalories * proteinPercentage;
var fatCalories = adjustedCalories * fatPercentage;
var carbCalories = adjustedCalories * carbPercentage;
// Convert calories to grams
var proteinGrams = proteinCalories / 4; // 4 kcal/gram for protein
var fatGrams = fatCalories / 9; // 9 kcal/gram for fat
var carbGrams = carbCalories / 4; // 4 kcal/gram for carbohydrates
// Display results
document.getElementById("totalCalories").innerText = Math.round(adjustedCalories);
document.getElementById("proteinGrams").innerText = Math.round(proteinGrams);
document.getElementById("proteinCalories").innerText = Math.round(proteinCalories);
document.getElementById("fatGrams").innerText = Math.round(fatGrams);
document.getElementById("fatCalories").innerText = Math.round(fatCalories);
document.getElementById("carbGrams").innerText = Math.round(carbGrams);
document.getElementById("carbCalories").innerText = Math.round(carbCalories);
document.getElementById("macroResults").style.display = "block";
}
.macro-inc-calculator-container {
font-family: 'Arial', sans-serif;
max-width: 600px;
margin: 20px auto;
padding: 30px;
border: 1px solid #ddd;
border-radius: 8px;
box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
background-color: #fff;
}
.macro-inc-calculator-form label {
font-weight: 600;
color: #333;
}
.macro-inc-calculator-form input[type="number"],
.macro-inc-calculator-form select {
margin-top: 5px;
margin-bottom: 10px;
border: 1px solid #ced4da;
border-radius: 4px;
padding: 10px;
font-size: 16px;
color: #495057;
box-sizing: border-box; /* Ensures padding doesn't increase total width */
}
.macro-inc-calculator-form input[type="radio"] {
margin-right: 5px;
}
.macro-inc-calculator-form button {
width: 100%;
padding: 12px;
font-size: 18px;
font-weight: bold;
border-radius: 5px;
transition: background-color 0.3s ease;
}
.macro-inc-calculator-form button:hover {
background-color: #0056b3;
}
#macroResults {
background-color: #e9f7ef;
border-color: #d4edda;
color: #155724;
}
#macroResults h3 {
color: #0f3d1a;
}
#macroResults ul {
margin-top: 15px;
}
#macroResults li {
padding: 8px 0;
border-bottom: 1px dashed #c3e6cb;
}
#macroResults li:last-child {
border-bottom: none;
}
Understanding Your Macronutrient Intake
Macronutrients, often simply called "macros," are the three main categories of nutrients that provide the bulk of energy to your body: proteins, carbohydrates, and fats. Each plays a crucial role in bodily functions, from building and repairing tissues to providing fuel for daily activities.
What are Macronutrients?
- Proteins: Essential for building and repairing muscle tissue, organs, skin, and hormones. They are made up of amino acids and are vital for growth and maintenance. (4 calories per gram)
- Carbohydrates: The body's primary source of energy. They are broken down into glucose, which fuels your brain, muscles, and other cells. (4 calories per gram)
- Fats: Crucial for hormone production, nutrient absorption (especially fat-soluble vitamins A, D, E, K), cell membrane integrity, and providing a concentrated source of energy. (9 calories per gram)
How the Calculator Works
Our Macronutrient Intake Calculator uses established scientific formulas to estimate your daily calorie and macronutrient needs. Here's a breakdown of the process:
- Basal Metabolic Rate (BMR): First, it calculates your BMR using the Mifflin-St Jeor Equation. This is the number of calories your body burns at rest to maintain basic life functions (breathing, circulation, cell production, etc.). Your age, gender, weight, and height are key factors here.
- Total Daily Energy Expenditure (TDEE): Your BMR is then multiplied by an activity factor to determine your TDEE. This accounts for the calories you burn through exercise and daily movement. The more active you are, the higher your TDEE.
- Goal Adjustment: Finally, your TDEE is adjusted based on your specific goal (e.g., weight loss, maintenance, or weight gain). For instance, a calorie deficit is created for weight loss, and a surplus for weight gain.
- Macronutrient Split: The calculator then divides your total adjusted daily calories into recommended percentages for protein, fats, and carbohydrates. These percentages are converted into grams based on their caloric density (4 kcal/g for protein and carbs, 9 kcal/g for fats).
Example Calculation:
Let's consider a 30-year-old male, 175 cm tall, weighing 70 kg, who is moderately active and aims for moderate weight loss.
- BMR Calculation (Mifflin-St Jeor): (10 * 70 kg) + (6.25 * 175 cm) – (5 * 30 years) + 5 = 700 + 1093.75 – 150 + 5 = 1648.75 kcal
- TDEE (Moderately Active Factor 1.55): 1648.75 kcal * 1.55 = 2555.56 kcal
- Goal Adjustment (Moderate Weight Loss – 500 kcal deficit): 2555.56 kcal – 500 kcal = 2055.56 kcal (approx. 2056 kcal)
- Macronutrient Split (Example: 30% Protein, 25% Fat, 45% Carbs):
- Protein: 2056 kcal * 0.30 = 616.8 kcal / 4 kcal/g = 154 grams
- Fats: 2056 kcal * 0.25 = 514 kcal / 9 kcal/g = 57 grams
- Carbohydrates: 2056 kcal * 0.45 = 925.2 kcal / 4 kcal/g = 231 grams
Based on these inputs, this individual would aim for approximately 2056 calories daily, broken down into 154g Protein, 57g Fats, and 231g Carbohydrates.
Important Considerations:
While this calculator provides a great starting point, remember that these are estimates. Individual needs can vary based on genetics, body composition, metabolic rate, and specific health conditions. For personalized dietary advice, especially if you have underlying health issues or specific athletic goals, it's always best to consult with a registered dietitian or healthcare professional.