Calorie Intake for Weight Gain Calculator

Calculate your daily calorie needs to achieve healthy weight gain.

Weight Gain Calorie Calculator

What is Calorie Intake for Weight Gain?

The concept of calorie intake for weight gain revolves around consuming more calories than your body burns to promote an increase in body mass. This is the fundamental principle of positive energy balance. For individuals seeking to gain weight, whether for athletic performance, recovery from illness, or aesthetic goals, understanding and implementing a strategic calorie intake is paramount. It's not just about eating more, but about eating the *right* foods in appropriate quantities to support healthy tissue growth, primarily muscle mass, rather than excessive fat accumulation.

Who should use it: This calculator is beneficial for:

• Individuals aiming to build muscle mass for sports or fitness.
• People recovering from conditions that led to significant weight loss.
• Anyone looking to increase their overall body weight in a controlled manner.
• Athletes requiring increased energy stores for performance.

Common misconceptions: A frequent misunderstanding is that any extra calories will lead to desired weight gain. However, focusing solely on quantity without considering macronutrient balance (protein, carbohydrates, fats) can lead to unhealthy fat gain, poor nutrient intake, and digestive discomfort. Another misconception is that weight gain must be rapid; a sustainable, gradual gain is generally healthier and more effective for building lean mass.

Calorie Intake for Weight Gain Formula and Mathematical Explanation

Calculating your optimal calorie intake for weight gain involves understanding your body's energy expenditure and strategically adding a surplus. The core idea is to create a consistent caloric surplus over time. Here's a breakdown of the formula and its components:

Step-by-Step Derivation

1. Calculate Basal Metabolic Rate (BMR): This is the minimum number of calories your body needs to perform basic life-sustaining functions at rest. While precise BMR requires height, age, and gender (often using formulas like Mifflin-St Jeor), for a simplified weight gain calculator, we can use a baseline estimate based on weight, acknowledging it's an approximation. A common general estimate is roughly 13-15 calories per pound of body weight, or 28-33 calories per kilogram. For our calculator, we'll use a simplified approach based on kilograms.
2. Determine Total Daily Energy Expenditure (TDEE): TDEE accounts for your BMR plus the calories burned through physical activity. It's calculated by multiplying your BMR by an activity factor that reflects your lifestyle. This TDEE value represents your maintenance calories – the amount needed to stay at your current weight.
3. Calculate Required Calorie Surplus: To gain weight, you must consume more calories than your TDEE. A general guideline is that a surplus of approximately 3,500 to 7,700 calories is needed to gain 0.5 to 1 kilogram (1 to 2 pounds) of body weight. We will use 7,700 kcal per kg for calculation purposes to aim for roughly 1 kg gain per week. This surplus is then divided by the number of days in your target timeframe to determine the daily surplus needed.
4. Calculate Target Daily Calorie Intake: Add your calculated daily calorie surplus to your TDEE. This final number is your target daily calorie intake for weight gain.

Variables Explained

Variables Used in Calculation

Variable	Meaning	Unit	Typical Range / Notes
Current Weight	Your current body mass.	kg or lbs	Positive number (e.g., 50-120 kg, 110-265 lbs)
Weight Unit	The unit of measurement for weight.	–	kg or lbs
Activity Level Multiplier	Factor representing daily physical activity.	Decimal (e.g., 1.2 – 1.9)	See calculator options (Sedentary to Extra Active).
Target Weight Gain	The amount of weight you aim to gain.	kg or lbs	Positive number (e.g., 2-10 kg, 5-20 lbs). Unit matches input weight unit.
Timeframe	Duration in weeks to achieve the target weight gain.	Weeks	Minimum 1 week.
BMR (Basal Metabolic Rate)	Estimated calories burned at rest.	kcal/day	Calculated value.
TDEE (Total Daily Energy Expenditure)	Estimated daily maintenance calories including activity.	kcal/day	Calculated value (BMR * Activity Multiplier).
Calorie Surplus (Daily)	Extra calories needed per day to gain weight.	kcal/day	Calculated value.
Calorie Surplus (Weekly)	Total extra calories needed per week.	kcal/week	Calculated value (Daily Surplus * 7).
Target Daily Calorie Intake	Your recommended daily calorie consumption for weight gain.	kcal/day	Calculated value (TDEE + Daily Surplus).
Estimated Weight Gain Per Week	Projected weekly weight gain based on surplus.	kg or lbs	Calculated value (Weekly Surplus / 7700 kcal/kg). Unit matches input weight unit.

Practical Examples (Real-World Use Cases)

Example 1: Muscle Building Focus

Scenario: Sarah is an intermediate lifter looking to add lean muscle mass. She currently weighs 60 kg and wants to gain 5 kg over 10 weeks. She trains 4-5 times a week with moderate intensity.

Inputs:

• Current Weight: 60 kg
• Weight Unit: kg
• Activity Level: Moderately Active (1.55)
• Target Weight Gain: 5 kg
• Timeframe: 10 weeks

Calculation Steps (Simplified):

• Approximate BMR: 60 kg * 30 kcal/kg ≈ 1800 kcal
• TDEE: 1800 kcal * 1.55 ≈ 2790 kcal (maintenance calories)
• Weekly Calorie Surplus Needed: (5 kg * 7700 kcal/kg) / 10 weeks = 3850 kcal/week
• Daily Calorie Surplus Needed: 3850 kcal / 7 days ≈ 550 kcal/day
• Target Daily Calorie Intake: 2790 kcal + 550 kcal ≈ 3340 kcal
• Estimated Weight Gain Per Week: 3850 kcal / 7700 kcal/kg = 0.5 kg/week

Outputs:

• Estimated Daily Calorie Surplus Needed: 550 kcal
• Basal Metabolic Rate (BMR): ~1800 kcal
• Total Daily Energy Expenditure (TDEE): ~2790 kcal
• Target Daily Calorie Intake for Weight Gain: ~3340 kcal
• Weekly Calorie Surplus Needed: ~3850 kcal
• Estimated Weight Gain Per Week: ~0.5 kg

Interpretation: Sarah needs to consume approximately 3340 calories per day to achieve a steady gain of about 0.5 kg per week, focusing on adequate protein intake to support muscle growth. This represents a 550 kcal daily surplus over her maintenance needs.

Example 2: Recovery and General Weight Increase

Scenario: John is recovering from an illness and needs to regain some lost weight. He currently weighs 150 lbs and wants to gain 10 lbs over 8 weeks. His activity level is currently light due to recovery.

Inputs:

• Current Weight: 150 lbs
• Weight Unit: lbs
• Activity Level: Lightly Active (1.375)
• Target Weight Gain: 10 lbs
• Timeframe: 8 weeks

Calculation Steps (using lbs conversion for surplus):

• Convert lbs to kg: 150 lbs / 2.20462 ≈ 68 kg
• Approximate BMR: 68 kg * 30 kcal/kg ≈ 2040 kcal
• TDEE: 2040 kcal * 1.375 ≈ 2805 kcal (maintenance calories)
• Weekly Calorie Surplus Needed (lbs): (10 lbs * 3500 kcal/lb) / 8 weeks = 4375 kcal/week (using 3500 kcal/lb for a slightly slower gain)
• Daily Calorie Surplus Needed: 4375 kcal / 7 days ≈ 625 kcal/day
• Target Daily Calorie Intake: 2805 kcal + 625 kcal ≈ 3430 kcal
• Estimated Weight Gain Per Week (lbs): 4375 kcal / 3500 kcal/lb = 1.25 lbs/week

Outputs:

• Estimated Daily Calorie Surplus Needed: ~625 kcal
• Basal Metabolic Rate (BMR): ~2040 kcal
• Total Daily Energy Expenditure (TDEE): ~2805 kcal
• Target Daily Calorie Intake for Weight Gain: ~3430 kcal
• Weekly Calorie Surplus Needed: ~4375 kcal
• Estimated Weight Gain Per Week: ~1.25 lbs

Interpretation: John should aim for a daily intake of around 3430 calories, adding about 625 calories to his maintenance level, to gain approximately 1.25 lbs per week. This gradual approach is suitable for recovery and healthier weight gain.

How to Use This Calorie Intake for Weight Gain Calculator

Using our calorie intake for weight gain calculator is straightforward and designed to provide actionable insights. Follow these steps:

1. Enter Current Weight: Input your current body weight in either kilograms (kg) or pounds (lbs).
2. Select Weight Unit: Ensure you choose the correct unit (kg or lbs) corresponding to your weight entry.
3. Choose Activity Level: Select the option that best describes your typical weekly physical activity. Be honest to get the most accurate TDEE estimate.
4. Specify Target Weight Gain: Enter the total amount of weight you aim to gain. Make sure the unit matches your current weight unit.
5. Set Timeframe: Indicate the number of weeks within which you want to achieve your target weight gain.
6. Click 'Calculate': The calculator will process your inputs and display your recommended daily calorie surplus, maintenance calories (TDEE), and target daily calorie intake for weight gain. It will also show the estimated weekly gain.

How to Read Results

• Estimated Daily Calorie Surplus Needed: This is the extra amount of calories you need to consume *above* your maintenance level each day.
• Basal Metabolic Rate (BMR): An estimate of calories burned at rest. Useful for understanding baseline energy needs.
• Total Daily Energy Expenditure (TDEE): Your estimated daily calorie needs to maintain your current weight.
• Target Daily Calorie Intake for Weight Gain: This is the total number of calories you should aim to consume daily to achieve your weight gain goals.
• Weekly Calorie Surplus Needed: The total caloric excess required over a week to meet your weight gain target.
• Estimated Weight Gain Per Week: The projected rate of weight gain based on the calculated surplus.

Decision-Making Guidance

The results provide a target, but remember that individual metabolism and body response can vary. Aim to consistently hit your target daily calorie intake. Prioritize nutrient-dense foods, particularly protein, to support muscle growth. If you're not gaining weight as expected, slightly increase your calorie intake (e.g., by 100-200 kcal) and reassess. If gaining too rapidly (mostly fat), slightly decrease your intake or ensure your training intensity is appropriate. Consult with a healthcare professional or registered dietitian for personalized advice, especially if you have underlying health conditions.

Key Factors That Affect Calorie Intake for Weight Gain Results

While the calculator provides a solid estimate, several factors can influence your actual calorie intake for weight gain needs and results:

1. Metabolic Rate Variations: Individual BMRs can differ significantly due to genetics, hormones, and body composition (muscle burns more calories than fat). Some people naturally have a faster metabolism, requiring more calories to gain weight.
2. Thermic Effect of Food (TEF): Digesting food requires energy. Protein has a higher TEF than carbohydrates or fats, meaning your body burns more calories processing protein. This is a minor factor but contributes to overall energy expenditure.
3. Non-Exercise Activity Thermogenesis (NEAT): This includes calories burned from all physical activity that isn't formal exercise – fidgeting, walking around, typing, etc. Higher NEAT can significantly increase daily calorie needs, making weight gain harder if not accounted for.
4. Hormonal Balance: Hormones like thyroid hormones, testosterone, and insulin play crucial roles in metabolism and muscle growth. Imbalances can affect appetite, nutrient absorption, and the body's ability to utilize calories effectively for muscle gain.
5. Nutrient Timing and Macronutrient Distribution: While total calories are king for weight gain, the *types* of calories matter for *what kind* of weight you gain. Adequate protein is essential for muscle synthesis, carbohydrates provide energy for workouts, and healthy fats support hormone production. Consuming protein around workouts can optimize muscle repair and growth.
6. Digestive Health and Absorption: If you have underlying digestive issues, you might not be absorbing nutrients efficiently, even if consuming enough calories. Conditions like malabsorption syndromes directly impact the usable energy derived from food.
7. Sleep Quality and Quantity: Insufficient or poor-quality sleep can disrupt hormones that regulate appetite (ghrelin and leptin) and muscle recovery (growth hormone), hindering muscle gain and potentially increasing fat storage.
8. Stress Levels: Chronic stress elevates cortisol levels, which can promote fat storage, particularly around the abdomen, and may interfere with muscle building processes.

Frequently Asked Questions (FAQ)

How many calories do I need to eat to gain 1 pound per week?

Generally, you need to create a surplus of approximately 3500 calories over the week. This translates to about a 500 calorie surplus per day (3500 calories / 7 days = 500 calories/day) added to your Total Daily Energy Expenditure (TDEE).

Is it better to gain weight slowly or quickly?

Slow and steady weight gain is generally recommended for healthier outcomes. Aiming for 0.5 to 1 pound (0.25 to 0.5 kg) of weight gain per week allows for more lean muscle mass accumulation and less unwanted fat gain compared to rapid weight gain.

What types of food should I focus on for weight gain?

Focus on nutrient-dense foods that are calorie-rich. Good choices include lean proteins (chicken, fish, lean beef, eggs, dairy, legumes), complex carbohydrates (oats, brown rice, quinoa, whole-wheat bread, potatoes), healthy fats (avocado, nuts, seeds, olive oil), and fruits/vegetables for micronutrients.

Can I use this calculator if I'm underweight?

Yes, this calculator is suitable for anyone looking to increase their body weight, including those who are underweight. It helps establish a caloric target for positive energy balance.

What if my weight gain stalls?

If your weight gain stalls, it likely means your body has adapted to your current calorie intake, and your TDEE has increased slightly due to your higher body weight. You may need to incrementally increase your daily calorie intake by another 200-300 kcal and reassess. Ensure you are accurately tracking your food intake.

Does exercise intensity affect my calorie needs for weight gain?

Yes, your activity level multiplier directly impacts your TDEE. Higher intensity or more frequent exercise burns more calories, requiring a higher overall calorie intake to achieve the same surplus. Weight training is particularly important for ensuring the gained weight is primarily muscle.

Is it possible to gain weight too fast?

Gaining weight too rapidly (e.g., more than 2 pounds or 1 kg per week consistently) often results in a higher proportion of fat gain rather than lean muscle. It can also put unnecessary strain on your body. A moderate pace is generally healthier and more sustainable.

Should I use supplements for weight gain?

Supplements like protein powders or mass gainers can be convenient tools to help meet high calorie and protein targets, but they are not essential. Focus on whole foods first. Supplements should complement a well-structured diet, not replace it. Always research and consult a professional before starting new supplements.

Related Tools and Internal Resources

• BMI Calculator Assess your current body mass index and understand its relation to weight categories.
• Macronutrient Calculator Determine the ideal ratio of protein, carbohydrates, and fats for your goals.
• Water Intake Calculator Calculate your daily hydration needs for optimal health and performance.
• TDEE Calculator Get a more detailed estimate of your Total Daily Energy Expenditure based on specific metrics.
• Healthy Eating Guide Learn principles of balanced nutrition to support your weight gain journey.
• Exercise for Muscle Gain Discover effective training strategies to maximize muscle hypertrophy.

function validateInput(id, errorId, min, max, isFloat) { var input = document.getElementById(id); var errorDiv = document.getElementById(errorId); var value = input.value.trim(); var errorMessage = ""; if (value === "") { errorMessage = "This field cannot be empty."; } else { var numValue = parseFloat(value); if (isNaN(numValue)) { errorMessage = "Please enter a valid number."; } else { if (isFloat === false && !Number.isInteger(numValue)) { errorMessage = "Please enter a whole number."; } if (min !== undefined && numValue max) { errorMessage = "Value cannot be greater than " + max + "."; } } } if (errorDiv) { errorDiv.textContent = errorMessage; } return errorMessage === ""; } function calculateCalories() { var isValid = true; isValid &= validateInput('currentWeight', 'currentWeightError', 0, null, true); isValid &= validateInput('goalWeight', 'goalWeightError', 0, null, true); isValid &= validateInput('timeframe', 'timeframeError', 1, null, false); // Timeframe should be integer > 0 if (!isValid) { document.getElementById('results').style.display = 'none'; return; } var currentWeight = parseFloat(document.getElementById('currentWeight').value); var weightUnit = document.getElementById('weightUnit').value; var activityLevel = parseFloat(document.getElementById('activityLevel').value); var goalWeight = parseFloat(document.getElementById('goalWeight').value); var timeframe = parseInt(document.getElementById('timeframe').value, 10); var weightKg; if (weightUnit === 'lbs') { weightKg = currentWeight / 2.20462; } else { weightKg = currentWeight; } // Simplified BMR approximation: weight in kg * 30 kcal/kg var bmr = weightKg * 30; var tdee = bmr * activityLevel; // Calculate surplus needed per kg of weight gain var kcalPerKg = 7700; // Standard estimate for 1 kg of body mass // Calculate total surplus needed for the goal weight gain var totalSurplusNeeded = goalWeight * kcalPerKg; // Calculate daily surplus needed var days = timeframe * 7; var dailySurplus = totalSurplusNeeded / days; // Calculate target daily intake var targetIntake = tdee + dailySurplus; // Calculate weekly surplus and estimated weekly gain var weeklySurplus = dailySurplus * 7; var estimatedWeeklyGainKg = weeklySurplus / kcalPerKg; var estimatedWeeklyGainLbs = estimatedWeeklyGainKg * 2.20462; document.getElementById('bmrResult').textContent = Math.round(bmr) + ' kcal'; document.getElementById('tdeeResult').textContent = Math.round(tdee) + ' kcal'; document.getElementById('calorieSurplus').textContent = Math.round(dailySurplus) + ' kcal'; document.getElementById('targetIntakeResult').textContent = Math.round(targetIntake) + ' kcal'; document.getElementById('weeklySurplus').textContent = Math.round(weeklySurplus) + ' kcal'; var displayGain; if (weightUnit === 'lbs') { displayGain = estimatedWeeklyGainLbs.toFixed(2) + ' lbs'; } else { displayGain = estimatedWeeklyGainKg.toFixed(2) + ' kg'; } document.getElementById('weeklyGain').textContent = displayGain; document.getElementById('results').style.display = 'block'; updateChart(tdee, targetIntake); } function resetCalculator() { document.getElementById('currentWeight').value = '70'; // Default kg document.getElementById('weightUnit').value = 'kg'; document.getElementById('activityLevel').value = '1.55'; // Moderately Active document.getElementById('goalWeight').value = '5'; // Default kg document.getElementById('timeframe').value = '10'; // Default weeks document.getElementById('currentWeightError').textContent = "; document.getElementById('goalWeightError').textContent = "; document.getElementById('timeframeError').textContent = "; // Reset results display document.getElementById('bmrResult').textContent = '– kcal'; document.getElementById('tdeeResult').textContent = '– kcal'; document.getElementById('calorieSurplus').textContent = '– kcal'; document.getElementById('targetIntakeResult').textContent = '– kcal'; document.getElementById('weeklySurplus').textContent = '– kcal'; document.getElementById('weeklyGain').textContent = '– kg/lbs'; document.getElementById('results').style.display = 'none'; // Clear chart var ctx = document.getElementById('calorieChart').getContext('2d'); ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height); ctx.font = "16px Segoe UI"; // Reset font for potential future rendering } function copyResults() { var resultsText = "Weight Gain Calculator Results:\n\n"; resultsText += "Estimated Daily Calorie Surplus Needed: " + document.getElementById('calorieSurplus').textContent + "\n"; resultsText += "Basal Metabolic Rate (BMR): " + document.getElementById('bmrResult').textContent + "\n"; resultsText += "Total Daily Energy Expenditure (TDEE): " + document.getElementById('tdeeResult').textContent + "\n"; resultsText += "Target Daily Calorie Intake for Weight Gain: " + document.getElementById('targetIntakeResult').textContent + "\n"; resultsText += "Weekly Calorie Surplus Needed: " + document.getElementById('weeklySurplus').textContent + "\n"; resultsText += "Estimated Weight Gain Per Week: " + document.getElementById('weeklyGain').textContent + "\n\n"; resultsText += "Key Assumptions:\n"; resultsText += "- Assumes ~7700 kcal surplus per kg of body weight gain.\n"; resultsText += "- BMR is an approximation based on weight and general activity.\n"; resultsText += "- Results are estimates and individual needs may vary.\n"; var textArea = document.createElement("textarea"); textArea.value = resultsText; document.body.appendChild(textArea); textArea.focus(); textArea.select(); try { var successful = document.execCommand('copy'); var msg = successful ? 'Results copied!' : 'Failed to copy results.'; // Optionally show a temporary message to the user // console.log(msg); } catch (err) { // console.log('Oops, unable to copy'); } document.body.removeChild(textArea); } // Chart Implementation var chartInstance = null; // To hold the chart instance function updateChart(tdee, targetIntake) { var canvas = document.getElementById('calorieChart'); var ctx = canvas.getContext('2d'); // Clear previous chart if it exists if (chartInstance) { chartInstance.destroy(); // Destroy previous chart instance if library is used (not applicable here) ctx.clearRect(0, 0, canvas.width, canvas.height); // Clear canvas manually } // Ensure valid numbers before charting if (isNaN(tdee) || isNaN(targetIntake) || tdee <= 0 || targetIntake <= 0) { ctx.font = "16px Segoe UI"; ctx.fillStyle = "#dc3545"; ctx.textAlign = "center"; ctx.fillText("Enter valid inputs to display chart.", canvas.width / 2, canvas.height / 2); return; } var chartData = { labels: ['Maintenance (TDEE)', 'Target for Gain'], datasets: [{ label: 'Calories (kcal)', data: [tdee, targetIntake], backgroundColor: [ 'rgba(0, 74, 153, 0.7)', // TDEE color 'rgba(40, 167, 69, 0.7)' // Target Intake color ], borderColor: [ 'rgba(0, 74, 153, 1)', 'rgba(40, 167, 69, 1)' ], borderWidth: 1 }] }; var chartOptions = { responsive: true, maintainAspectRatio: false, scales: { y: { beginAtZero: true, ticks: { callback: function(value) { return value + ' kcal'; } } } }, plugins: { legend: { display: true, position: 'top', }, title: { display: true, text: 'Daily Calorie Needs for Weight Gain', font: { size: 18 } } } }; // Custom drawing using Canvas API (since no external library allowed) var chartHeight = canvas.height; var chartWidth = canvas.width; var barWidth = (chartWidth * 0.8) / chartData.labels.length; // Allocate 80% of width for bars var padding = (chartWidth * 0.2) / (chartData.labels.length + 1); // Padding between bars and sides // Find max value for scaling var maxValue = Math.max(tdee, targetIntake); var scaleFactor = (chartHeight * 0.8) / maxValue; // Use 80% of height for bars // Draw Title ctx.font = 'bold 18px Segoe UI'; ctx.fillStyle = '#004a99'; ctx.textAlign = 'center'; ctx.fillText(chartOptions.plugins.title.text, chartWidth / 2, 30); // Draw Bars chartData.datasets[0].data.forEach(function(value, index) { var barHeight = value * scaleFactor; var x = padding + index * (barWidth + padding); var y = chartHeight – 50 – barHeight; // Adjust for bottom padding and labels // Draw background color ctx.fillStyle = chartData.datasets[0].backgroundColor[index]; ctx.fillRect(x, y, barWidth, barHeight); // Draw border ctx.strokeStyle = chartData.datasets[0].borderColor[index]; ctx.lineWidth = chartData.datasets[0].borderWidth; ctx.strokeRect(x, y, barWidth, barHeight); // Draw value label on top of bar ctx.fillStyle = '#333'; ctx.font = '14px Segoe UI'; ctx.textAlign = 'center'; ctx.fillText(Math.round(value) + ' kcal', x + barWidth / 2, y – 10); }); // Draw Labels ctx.fillStyle = '#333'; ctx.font = '14px Segoe UI'; chartData.labels.forEach(function(label, index) { var x = padding + index * (barWidth + padding) + barWidth / 2; ctx.textAlign = 'center'; ctx.fillText(label, x, chartHeight – 20); }); // Draw Legend (simplified) var legendY = chartHeight – 70; chartData.labels.forEach(function(label, index) { ctx.fillStyle = chartData.datasets[0].backgroundColor[index]; ctx.fillRect(padding + index * (barWidth + padding), legendY, 20, 10); // Color swatch ctx.fillStyle = '#333'; ctx.font = '14px Segoe UI'; ctx.textAlign = 'left'; ctx.fillText(label + " (" + chartData.datasets[0].data[index].toFixed(0) + " kcal)", padding + index * (barWidth + padding) + 30, legendY + 10); }); } // Initial chart setup (empty or with placeholders) function setupInitialChart() { var canvas = document.getElementById('calorieChart'); var ctx = canvas.getContext('2d'); ctx.font = "16px Segoe UI"; ctx.fillStyle = "#6c757d"; ctx.textAlign = "center"; ctx.fillText("Enter your details to see the chart.", canvas.width / 2, canvas.height / 2); } // Add event listeners for real-time updates (optional, but good practice) document.getElementById('currentWeight').addEventListener('input', calculateCalories); document.getElementById('weightUnit').addEventListener('change', calculateCalories); document.getElementById('activityLevel').addEventListener('change', calculateCalories); document.getElementById('goalWeight').addEventListener('input', calculateCalories); document.getElementById('timeframe').addEventListener('input', calculateCalories); // Initialize the calculator and chart on load window.onload = function() { resetCalculator(); // Set default values setupInitialChart(); // Setup placeholder chart // Ensure chart area exists before trying to update if(document.getElementById('calorieChart')) { // Initial calculation with default values calculateCalories(); } }; // FAQ functionality var faqQuestions = document.querySelectorAll('.faq-question'); faqQuestions.forEach(function(question) { question.addEventListener('click', function() { var answer = this.nextElementSibling; if (answer.style.display === 'block') { answer.style.display = 'none'; this.classList.remove('active'); } else { answer.style.display = 'block'; this.classList.add('active'); } }); });