Weight Loss Macro Calculator

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Weight Loss Macro Calculator

Male Female
Sedentary (Office job, little exercise) Lightly Active (Light exercise 1-3 days/week) Moderately Active (Moderate exercise 3-5 days/week) Very Active (Hard exercise 6-7 days/week) Extra Active (Very hard exercise & physical job)
Mild Weight Loss (0.25 kg/week) Standard Weight Loss (0.5 kg/week) Extreme Weight Loss (1 kg/week)

Your Daily Targets

Target Calories: 0 kcal/day
0g Protein
0g Carbohydrates
0g Fats

How to Use the Weight Loss Macro Calculator

Achieving sustainable weight loss is a science of energy balance. This calculator uses the Mifflin-St Jeor Equation, widely considered the most accurate formula for calculating Basal Metabolic Rate (BMR). By inputting your biological data and activity levels, you can determine exactly how many calories and macronutrients you need to burn fat while preserving muscle mass.

Understanding Your Results

Your results are divided into four main components:

  • Calories: This is your "Caloric Deficit" target. It is calculated by taking your Total Daily Energy Expenditure (TDEE) and subtracting your chosen goal deficit.
  • Protein (4 kcal/g): Essential for muscle preservation and satiety. Our calculator sets protein at approximately 2.2g per kg of body weight for optimal fat loss.
  • Fats (9 kcal/g): Crucial for hormone production. We allocate roughly 25% of your total calories to healthy fats.
  • Carbohydrates (4 kcal/g): Your body's primary fuel source. The remaining calories after protein and fat are allocated to carbs to fuel your workouts.

Example Calculation

Consider a 35-year-old male weighing 90kg, standing 180cm tall, with a moderately active lifestyle. His BMR would be roughly 1,880 calories. After applying the activity factor (1.55), his maintenance calories (TDEE) are 2,914. To lose 0.5kg per week, he needs a 500-calorie deficit, resulting in a target of 2,414 calories per day. His macros would be roughly 198g Protein, 67g Fat, and 255g Carbs.

Tips for Success

1. Be Honest with Activity: Most people overestimate their activity level. If you work at a desk and hit the gym 3 times a week, "Lightly Active" is usually the safest starting point.

2. Consistency Over Perfection: It is better to hit your numbers 80% of the time than to be perfect for three days and quit.

3. Adjust as You Go: As you lose weight, your BMR decreases. Recalculate your macros every 5kg lost to ensure you don't hit a plateau.

function calculateMacros() { // Get Input Values var gender = document.getElementById("gender").value; var age = parseFloat(document.getElementById("age").value); var weight = parseFloat(document.getElementById("weight").value); var height = parseFloat(document.getElementById("height").value); var activity = parseFloat(document.getElementById("activity").value); var deficit = parseFloat(document.getElementById("goal").value); // Validation if (isNaN(age) || isNaN(weight) || isNaN(height)) { alert("Please enter valid numbers for age, weight, and height."); return; } // BMR Calculation (Mifflin-St Jeor) var bmr; if (gender === "male") { bmr = (10 * weight) + (6.25 * height) – (5 * age) + 5; } else { bmr = (10 * weight) + (6.25 * height) – (5 * age) – 161; } // TDEE Calculation var tdee = bmr * activity; // Target Calories var targetCalories = tdee – deficit; // Ensure calories don't drop below safety thresholds (1200 for women, 1500 for men) var floor = (gender === "male") ? 1500 : 1200; if (targetCalories < floor) { targetCalories = floor; } // Macro Logic // 1. Protein: 2.2g per kg of weight var proteinGrams = weight * 2.2; var proteinCalories = proteinGrams * 4; // 2. Fats: 25% of total target calories var fatCalories = targetCalories * 0.25; var fatGrams = fatCalories / 9; // 3. Carbs: Remaining calories var carbCalories = targetCalories – proteinCalories – fatCalories; // Safety check if protein is set too high for the calorie goal if (carbCalories < (targetCalories * 0.15)) { // Adjust protein down if carbs become too low (less than 15%) carbCalories = targetCalories * 0.15; proteinCalories = targetCalories – carbCalories – fatCalories; proteinGrams = proteinCalories / 4; } var carbGrams = carbCalories / 4; // Display Results document.getElementById("res_calories").innerText = Math.round(targetCalories).toLocaleString(); document.getElementById("res_protein").innerText = Math.round(proteinGrams) + "g"; document.getElementById("res_fats").innerText = Math.round(fatGrams) + "g"; document.getElementById("res_carbs").innerText = Math.round(carbGrams) + "g"; document.getElementById("results").style.display = "block"; // Scroll to results document.getElementById("results").scrollIntoView({ behavior: 'smooth', block: 'nearest' }); }

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