Iifym Calculator

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IIFYM Macro Calculator

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 a week) Extremely Active (very hard exercise/physical job/training twice a day)
Lose Weight (approx. 1 lb/week) Maintain Weight Gain Weight (approx. 1 lb/week)

Your IIFYM Targets:

Target Calories: kcal

Protein: grams

Fat: grams

Carbohydrates: grams

function calculateIIFYM() { var gender = document.getElementById('iifymGender').value; var age = parseFloat(document.getElementById('iifymAge').value); var weightLbs = parseFloat(document.getElementById('iifymWeight').value); var heightInches = parseFloat(document.getElementById('iifymHeight').value); var activityLevel = document.getElementById('iifymActivity').value; var goal = document.getElementById('iifymGoal').value; // Input validation if (isNaN(age) || isNaN(weightLbs) || isNaN(heightInches) || age <= 0 || weightLbs <= 0 || heightInches <= 0) { document.getElementById('iifymResult').style.display = 'block'; document.getElementById('iifymResult').style.backgroundColor = '#f8d7da'; document.getElementById('iifymResult').style.borderColor = '#f5c6cb'; document.getElementById('iifymResult').innerHTML = '

Error: Please enter valid positive numbers for Age, Weight, and Height.

'; return; } // Convert to metric for Mifflin-St Jeor var weightKg = weightLbs * 0.453592; var heightCm = heightInches * 2.54; var bmr; if (gender === 'male') { bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * age) + 5; } else { // female bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * age) – 161; } var tdee; switch (activityLevel) { case 'sedentary': tdee = bmr * 1.2; break; case 'light': tdee = bmr * 1.375; break; case 'moderate': tdee = bmr * 1.55; break; case 'very': tdee = bmr * 1.725; break; case 'extreme': tdee = bmr * 1.9; break; default: tdee = bmr * 1.55; // Default to moderate } var targetCalories; var calorieAdjustment = 500; // Common adjustment for ~1lb/week if (goal === 'lose') { targetCalories = tdee – calorieAdjustment; } else if (goal === 'gain') { targetCalories = tdee + calorieAdjustment; } else { // maintain targetCalories = tdee; } // Ensure calories don't go too low for safety if (targetCalories < 1200 && gender === 'female') { targetCalories = 1200; } else if (targetCalories < 1500 && gender === 'male') { targetCalories = 1500; } // Macronutrient distribution (common IIFYM percentages) var proteinPercentage = 0.30; // 30% of calories var fatPercentage = 0.25; // 25% of calories var carbPercentage = 1 – proteinPercentage – fatPercentage; // Remaining 45% var proteinCalories = targetCalories * proteinPercentage; var fatCalories = targetCalories * fatPercentage; var carbCalories = targetCalories * carbPercentage; var proteinGrams = proteinCalories / 4; // 4 calories per gram of protein var fatGrams = fatCalories / 9; // 9 calories per gram of fat var carbGrams = carbCalories / 4; // 4 calories per gram of carbohydrate document.getElementById('iifymCalories').innerText = Math.round(targetCalories); document.getElementById('iifymProtein').innerText = Math.round(proteinGrams); document.getElementById('iifymFat').innerText = Math.round(fatGrams); document.getElementById('iifymCarbs').innerText = Math.round(carbGrams); document.getElementById('iifymResult').style.display = 'block'; document.getElementById('iifymResult').style.backgroundColor = '#e9f7ee'; document.getElementById('iifymResult').style.borderColor = '#d4edda'; }

Understanding IIFYM: If It Fits Your Macros

The "If It Fits Your Macros" (IIFYM) approach to nutrition, often referred to as flexible dieting, has gained immense popularity for its practical and sustainable nature. Unlike restrictive diets that ban entire food groups, IIFYM focuses on meeting specific daily targets for macronutrients (protein, fats, and carbohydrates) and total calories, allowing for flexibility in food choices as long as those targets are met.

What are Macronutrients?

Macronutrients are the nutrients your body needs in large amounts to provide energy and support bodily functions. They include:

  • Protein: Essential for building and repairing tissues, producing enzymes and hormones, and supporting immune function. (4 calories per gram)
  • Fats: Crucial for hormone production, nutrient absorption, cell growth, and providing a concentrated source of energy. (9 calories per gram)
  • Carbohydrates: The body's primary source of energy, fueling your brain and muscles. (4 calories per gram)

How IIFYM Works

The core principle of IIFYM involves calculating your individual caloric needs and then breaking those calories down into specific macronutrient targets. This process typically follows these steps:

  1. Basal Metabolic Rate (BMR): This is the number of calories your body burns at rest to maintain basic life-sustaining functions (breathing, circulation, cell production). Our calculator uses the Mifflin-St Jeor equation, which is widely considered one of the most accurate BMR formulas.
  2. Total Daily Energy Expenditure (TDEE): Your TDEE is your BMR adjusted for your activity level. It represents the total number of calories you burn in a day, including exercise and daily movement.
  3. Calorie Goal Adjustment: Based on your fitness goal (weight loss, maintenance, or gain), your TDEE is adjusted. For weight loss, a caloric deficit is created (e.g., 500 calories below TDEE); for weight gain, a surplus is added (e.g., 500 calories above TDEE).
  4. Macronutrient Distribution: Once your target calorie intake is established, these calories are allocated to protein, fats, and carbohydrates based on common ratios. While these ratios can be customized, a typical starting point might be 30% protein, 25% fat, and 45% carbohydrates.

Benefits of Flexible Dieting

  • Sustainability: By allowing a variety of foods, IIFYM can be easier to stick to long-term compared to highly restrictive diets.
  • Education: It teaches you about the nutritional content of foods, helping you make more informed choices.
  • Flexibility: You can enjoy social events and occasional treats without derailing your progress, as long as they fit within your daily macro targets.
  • Results: When consistently applied, IIFYM is an effective method for achieving body composition goals, whether it's fat loss or muscle gain.

How to Use the IIFYM Calculator

Our IIFYM calculator simplifies the process of determining your personalized macro targets. Simply input the following information:

  • Gender: Select male or female.
  • Age: Your age in years.
  • Weight: Your current body weight in pounds (lbs).
  • Height: Your height in inches.
  • Activity Level: Choose the option that best describes your daily physical activity. Be honest for accurate results.
  • Goal: Select whether you want to lose weight, maintain your current weight, or gain weight.

Click "Calculate My Macros," and the calculator will instantly provide your estimated daily calorie target, along with the recommended grams of protein, fat, and carbohydrates.

Example Calculation:

Let's say we have a 30-year-old female, weighing 150 lbs, 68 inches tall, moderately active, and aiming to lose weight. Here's how the calculator would work:

  • Inputs: Gender: Female, Age: 30, Weight: 150 lbs, Height: 68 inches, Activity: Moderately Active, Goal: Lose Weight.
  • BMR Calculation: Approximately 1449 calories.
  • TDEE Calculation: BMR * 1.55 (for moderately active) = 2246 calories.
  • Calorie Goal: TDEE – 500 (for weight loss) = 1746 calories.
  • Macro Distribution (approximate):
    • Protein (30%): 131 grams (524 calories)
    • Fat (25%): 49 grams (441 calories)
    • Carbohydrates (45%): 196 grams (784 calories)

These targets provide a starting point. You may need to adjust them slightly based on your body's response and how you feel. Listen to your body, track your progress, and make small, consistent adjustments as needed.

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