Number of Calories to Lose Weight Calculator

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Calculate Your Calorie Needs for Weight Loss

Estimated Weekly Calorie Consumption and Weight Loss

Week	Starting Weight (kg)	Target Daily Intake (kcal)	Estimated End Weight (kg)

This table shows a projected view of your weight loss over several weeks based on consistent calorie intake and deficit.

Understanding the Number of Calories to Lose Weight Calculator

What is the Number of Calories to Lose Weight Calculator?

The number of calories to lose weight calculator is a tool designed to help individuals determine their specific daily caloric intake required to achieve a safe and sustainable rate of weight loss. It takes into account several personal factors, including current weight, target weight, desired weekly loss, age, gender, height, and activity level, to provide a personalized calorie target. This tool is invaluable for anyone looking to manage their weight effectively by creating an appropriate calorie deficit without resorting to overly restrictive or unhealthy eating patterns. It’s a cornerstone for informed dietary planning and healthy lifestyle changes, moving beyond generic advice to offer data-driven recommendations.

Who should use it? Anyone aiming to lose weight, whether it’s a few kilograms or a more significant amount, can benefit from this calculator. It’s particularly useful for individuals who have a specific weight loss goal in mind and want to understand the nutritional science behind achieving it. It’s also a great resource for fitness enthusiasts looking to fine-tune their diet for optimal body composition, or for those who have struggled with weight loss in the past and need a more structured, personalized approach. This calculator empowers users with knowledge, helping them to make informed food choices that align with their weight loss objectives.

Common misconceptions: A prevalent misconception is that all calories are equal, regardless of source. While the calculator focuses on caloric quantity, nutritional quality is crucial for health and satiety. Another myth is that extreme calorie restriction is the fastest or best way to lose weight; in reality, this can be detrimental to metabolism and overall health. Furthermore, many believe weight loss is purely about willpower, overlooking the significant physiological and metabolic factors that influence it. This tool helps demystify the process by providing a quantitative target based on established metabolic principles.

Number of Calories to Lose Weight Calculator Formula and Mathematical Explanation

The core of the number of calories to lose weight calculator relies on estimating your Total Daily Energy Expenditure (TDEE) and then creating a deficit. Here’s a breakdown:

1. Basal Metabolic Rate (BMR): This is the number of calories your body burns at rest to maintain basic functions. We use the Mifflin-St Jeor equation, which is widely considered more accurate than the older Harris-Benedict equation:
   • For men: BMR = (10 * weight in kg) + (6.25 * height in cm) – (5 * age in years) + 5
   • For women: BMR = (10 * weight in kg) + (6.25 * height in cm) – (5 * age in years) – 161
2. Total Daily Energy Expenditure (TDEE): This estimates your total daily calorie burn, factoring in your BMR and activity level. It’s calculated by multiplying your BMR by an activity factor:
   • TDEE = BMR * Activity Factor

   The activity factors are standard multipliers: Sedentary (1.2), Lightly Active (1.375), Moderately Active (1.55), Very Active (1.725), Extra Active (1.9).

3. Calorie Deficit for Weight Loss: A commonly accepted principle is that a deficit of approximately 3500 calories is required to lose 1 pound (0.45 kg) of body fat. To achieve a weekly weight loss target (e.g., 0.5 kg/week), we calculate the necessary weekly deficit:
   • Weekly Deficit = Target Weekly Weight Loss (kg) * 7700 kcal/kg (since 1 kg fat ≈ 7700 kcal)
4. Target Daily Calorie Intake: To find your daily calorie target for weight loss, we subtract the required weekly deficit from your TDEE and divide by 7:
   • Target Daily Intake = (TDEE – (Weekly Deficit / 7))

This provides a personalized calorie goal for weight loss. It’s crucial to remember that this is an estimate, and individual metabolism can vary. Adjustments may be needed based on personal results and how your body responds.

Variables Table

Variable	Meaning	Unit	Typical Range
Weight	Current body mass	Kilograms (kg)	30 – 300+ kg
Target Weight	Desired body mass	Kilograms (kg)	30 – 300+ kg
Weight Loss Rate	Desired weekly reduction in body mass	Kilograms per week (kg/week)	0.25 – 1.0 kg/week
Age	User’s age	Years	16 – 90+ years
Gender	User’s gender (influences BMR calculation)	–	Male / Female
Height	User’s physical stature	Centimeters (cm)	100 – 220+ cm
Activity Factor	Multiplier based on physical activity level	–	1.2 – 1.9
BMR	Calories burned at rest	Kilocalories (kcal)	~1000 – 2500+ kcal
TDEE	Total calories burned daily including activity	Kilocalories (kcal)	~1500 – 4000+ kcal
Weekly Deficit	Total calorie deficit needed per week for desired weight loss	Kilocalories (kcal)	~1925 – 7700 kcal
Target Daily Intake	Recommended daily calorie consumption for weight loss	Kilocalories (kcal)	~1000 – 3000+ kcal

Practical Examples (Real-World Use Cases)

Let’s explore how the number of calories to lose weight calculator can be used with practical examples:

Example 1: Sarah, aiming for moderate weight loss

Sarah is a 30-year-old female, 170 cm tall, weighing 75 kg. She leads a moderately active lifestyle (exercises 3-5 days/week) and wants to lose 0.5 kg per week. Her target weight is 68 kg.

• Inputs: Current Weight: 75 kg, Target Weight: 68 kg, Weekly Loss Rate: 0.5 kg/week, Age: 30, Gender: Female, Height: 170 cm, Activity Level: Moderately Active (1.55).
• Calculations:
  • BMR (Female): (10 * 75) + (6.25 * 170) – (5 * 30) – 161 = 750 + 1062.5 – 150 – 161 = 1501.5 kcal
  • TDEE: 1501.5 * 1.55 = 2327.3 kcal
  • Weekly Deficit (for 0.5 kg): 0.5 kg * 7700 kcal/kg = 3850 kcal
  • Daily Deficit: 3850 kcal / 7 days = 550 kcal
  • Target Daily Intake: 2327.3 – 550 = 1777.3 kcal
• Results: Sarah’s target daily calorie intake for losing 0.5 kg per week is approximately 1777 kcal. Her BMR is around 1502 kcal, and her TDEE is about 2327 kcal.
• Interpretation: Sarah should aim to consume around 1777 calories daily. This provides a sustainable deficit without being overly restrictive, allowing her to reach her goal of 68 kg in about 14 weeks (7 kg / 0.5 kg/week).

Example 2: Mark, aiming for a more aggressive loss

Mark is a 45-year-old male, 185 cm tall, weighing 100 kg. He is very active (exercises 6-7 days/week) and wants to lose 1 kg per week. His target weight is 90 kg.

• Inputs: Current Weight: 100 kg, Target Weight: 90 kg, Weekly Loss Rate: 1 kg/week, Age: 45, Gender: Male, Height: 185 cm, Activity Level: Very Active (1.725).
• Calculations:
  • BMR (Male): (10 * 100) + (6.25 * 185) – (5 * 45) + 5 = 1000 + 1156.25 – 225 + 5 = 1936.25 kcal
  • TDEE: 1936.25 * 1.725 = 3340.7 kcal
  • Weekly Deficit (for 1 kg): 1 kg * 7700 kcal/kg = 7700 kcal
  • Daily Deficit: 7700 kcal / 7 days = 1100 kcal
  • Target Daily Intake: 3340.7 – 1100 = 2240.7 kcal
• Results: Mark’s target daily calorie intake for losing 1 kg per week is approximately 2241 kcal. His BMR is around 1936 kcal, and his TDEE is about 3341 kcal.
• Interpretation: Mark needs to consume around 2241 calories daily to achieve his goal of losing 1 kg per week. While this is an aggressive rate, his high TDEE allows for a significant deficit while still consuming a substantial amount of calories, which can help with adherence. He could reach his goal in approximately 10 weeks (10 kg / 1 kg/week).

How to Use This Number of Calories to Lose Weight Calculator

Using the number of calories to lose weight calculator is straightforward and designed for user-friendliness. Follow these simple steps:

1. Enter Your Current Weight: Input your current body weight in kilograms (kg).
2. Input Your Target Weight: Enter the weight you aim to achieve in kilograms (kg).
3. Select Desired Weekly Weight Loss Rate: Choose a realistic rate, such as 0.5 kg per week, which is generally recommended for sustainable loss. Options like 0.25 kg/week are slower but more manageable, while 1 kg/week is aggressive and may not be suitable for everyone.
4. Choose Your Activity Level: Accurately select your lifestyle’s physical activity level. This is crucial as it significantly impacts your TDEE. Be honest to get the most accurate results.
5. Enter Age, Gender, and Height: Provide your age in years, select your gender, and enter your height in centimeters (cm). These factors are essential for the BMR calculation.
6. Click ‘Calculate’: Once all fields are filled, click the ‘Calculate’ button.

How to read results: The calculator will display your estimated Basal Metabolic Rate (BMR), your Total Daily Energy Expenditure (TDEE), the calculated weekly calorie deficit needed, and your target daily calorie intake for weight loss. The main result highlights your target daily intake in a prominent display.

Decision-making guidance: Your target daily calorie intake is a guideline. Focus on consuming nutrient-dense foods to feel full and satisfied. If you find it too difficult to stick to the target, consider adjusting your weight loss rate to a slower pace or increasing your activity level slightly. Listen to your body; if you feel consistently deprived or fatigued, the target might be too low. Conversely, if you aren’t losing weight, you may need to create a slightly larger deficit by adjusting intake or activity. Remember to consult with a healthcare professional or registered dietitian for personalized advice, especially with significant weight loss goals or underlying health conditions.

Key Factors That Affect Number of Calories to Lose Weight Calculator Results

While the number of calories to lose weight calculator provides a personalized estimate, several factors can influence its accuracy and your actual weight loss journey:

• Metabolic Adaptation: As you lose weight, your BMR and TDEE can decrease. The calculator doesn’t typically adjust for this ongoing adaptation, meaning you might need to gradually reduce intake or increase activity over time to maintain progress.
• Body Composition: Muscle tissue burns more calories at rest than fat tissue. Someone with a higher muscle mass will have a higher BMR than someone of the same weight but with less muscle. The calculator uses weight and height but doesn’t directly measure body fat percentage.
• Hormonal Fluctuations: Hormones play a significant role in metabolism and appetite. Conditions like hypothyroidism or PCOS can alter metabolic rate, making calorie calculations less precise.
• Dietary Adherence and Accuracy: The calculator assumes you accurately track and consume the calculated calorie amount. In reality, portion size errors, underestimation of calorie-dense foods, and ‘hidden’ calories (e.g., in sauces, drinks) can significantly impact results.
• Thermic Effect of Food (TEF): Different macronutrients have varying TEFs (the calories burned during digestion). Protein has a higher TEF than fats or carbohydrates, meaning a high-protein diet can slightly increase calorie expenditure. This is not explicitly factored into the basic TDEE calculation.
• Sleep Quality and Stress Levels: Poor sleep and high stress can negatively impact hormones like cortisol and ghrelin, potentially increasing appetite, promoting fat storage, and slowing down weight loss, even if calorie intake is consistent.
• Hydration: Adequate water intake is essential for metabolism and can sometimes help with appetite control. While not a direct input, dehydration can subtly affect metabolic processes.
• Individual Genetic Factors: Genetics can influence how efficiently your body uses calories, stores fat, and responds to exercise and dietary changes.

Frequently Asked Questions (FAQ)

• Q1: How accurate is the number of calories to lose weight calculator?

  The calculator provides an excellent estimate based on established formulas like Mifflin-St Jeor. However, it’s a guideline. Individual metabolic rates, body composition, genetics, and hormonal factors can cause variations. It’s a starting point, not an absolute rule.

• Q2: Is a 0.5 kg per week weight loss rate safe?

  Yes, a weight loss rate of 0.5 kg (about 1 pound) per week is generally considered safe, sustainable, and healthy for most individuals. It typically involves a moderate calorie deficit that is less likely to cause significant muscle loss or metabolic slowdown.

• Q3: What if my target weight is lower than my BMR suggests?

  If your calculated target daily intake for weight loss drops below your BMR, it suggests you are aiming for a very aggressive deficit. This is often unsustainable and can be unhealthy. In such cases, it’s recommended to either increase your activity level significantly or aim for a slower weight loss rate to maintain a healthier intake.

• Q4: Do I need to adjust my intake as I lose weight?

  Yes, ideally. As you lose weight, your body mass decreases, leading to a lower BMR and TDEE. To continue losing weight at the same rate, you may need to recalculate your needs periodically or make small adjustments to your calorie intake or activity level.

• Q5: Can I eat anything as long as it fits my calorie target?

  While staying within your calorie goal is primary for weight loss, nutritional quality matters. Focusing on whole foods (vegetables, fruits, lean proteins, whole grains) provides essential nutrients, fiber, and satiety, making the diet more sustainable and healthier overall compared to consuming the same calories from processed or nutrient-poor sources.

• Q6: What if I exercise intensely? Should I eat more?

  The ‘Activity Level’ input already accounts for your exercise. If you have very intense workouts or specific athletic training, you might need to add calories back to compensate for the energy expenditure during exercise. The calculator provides a baseline; listen to your body’s hunger cues and energy levels.

• Q7: Does this calculator account for muscle gain while losing fat?

  This calculator primarily focuses on calorie deficit for fat loss. Body recomposition (losing fat and gaining muscle simultaneously) is possible, especially for beginners, but requires careful attention to protein intake and strength training. The calorie target here is for net weight loss, assuming a primary goal of reducing body mass.

• Q8: How long will it take to reach my target weight?

  The calculator can provide an estimate. Divide the total weight you want to lose (in kg) by your desired weekly loss rate (in kg/week). For example, losing 10 kg at 0.5 kg/week would take approximately 20 weeks. This is an estimate and actual duration can vary.

Related Tools and Internal Resources

var chartInstance = null; // Global variable to hold the chart instance

function calculateCalories() {
var currentWeight = parseFloat(document.getElementById(‘currentWeight’).value);
var targetWeight = parseFloat(document.getElementById(‘targetWeight’).value);
var weightLossRate = parseFloat(document.getElementById(‘weightLossRate’).value);
var activityLevel = parseFloat(document.getElementById(‘activityLevel’).value);
var age = parseInt(document.getElementById(‘age’).value);
var gender = document.getElementById(‘gender’).value;
var height = parseFloat(document.getElementById(‘height’).value);

// Clear previous errors
document.getElementById(‘currentWeightError’).classList.remove(‘visible’);
document.getElementById(‘targetWeightError’).classList.remove(‘visible’);
document.getElementById(‘weightLossRateError’).classList.remove(‘visible’);
document.getElementById(‘activityLevelError’).classList.remove(‘visible’);
document.getElementById(‘ageError’).classList.remove(‘visible’);
document.getElementById(‘genderError’).classList.remove(‘visible’);
document.getElementById(‘heightError’).classList.remove(‘visible’);

var isValid = true;

if (isNaN(currentWeight) || currentWeight <= 0) {
document.getElementById('currentWeightError').textContent = "Please enter a valid current weight (e.g., 70).";
document.getElementById('currentWeightError').classList.add('visible');
isValid = false;
}
if (isNaN(targetWeight) || targetWeight = currentWeight) {
document.getElementById(‘targetWeightError’).textContent = “Target weight must be less than current weight.”;
document.getElementById(‘targetWeightError’).classList.add(‘visible’);
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}
if (isNaN(age) || age 120) {
document.getElementById(‘ageError’).textContent = “Please enter a valid age (e.g., 30).”;
document.getElementById(‘ageError’).classList.add(‘visible’);
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}
if (isNaN(height) || height 250) {
document.getElementById(‘heightError’).textContent = “Please enter a valid height in cm (e.g., 175).”;
document.getElementById(‘heightError’).classList.add(‘visible’);
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}
if (isNaN(weightLossRate)) { // activityLevel is already float, so check is simpler
document.getElementById(‘weightLossRateError’).textContent = “Please select a valid weight loss rate.”;
document.getElementById(‘weightLossRateError’).classList.add(‘visible’);
isValid = false;
}
if (isNaN(activityLevel)) {
document.getElementById(‘activityLevelError’).textContent = “Please select a valid activity level.”;
document.getElementById(‘activityLevelError’).classList.add(‘visible’);
isValid = false;
}
if (gender !== ‘male’ && gender !== ‘female’) {
document.getElementById(‘genderError’).textContent = “Please select a valid gender.”;
document.getElementById(‘genderError’).classList.add(‘visible’);
isValid = false;
}

if (!isValid) {
document.getElementById(‘resultsContainer’).style.display = ‘none’;
return;
}

var bmr = 0;
if (gender === ‘male’) {
bmr = (10 * currentWeight) + (6.25 * height) – (5 * age) + 5;
} else { // female
bmr = (10 * currentWeight) + (6.25 * height) – (5 * age) – 161;
}

var tdee = bmr * activityLevel;
var weeklyDeficitRequired = weightLossRate * 7700; // Approx 7700 kcal per kg of fat
var dailyDeficitRequired = weeklyDeficitRequired / 7;
var targetDailyIntake = tdee – dailyDeficitRequired;

// Ensure target intake is not below a safe minimum (e.g., 1000 kcal for women, 1200 for men)
var minIntake = (gender === ‘female’) ? 1000 : 1200;
if (targetDailyIntake < minIntake) {
targetDailyIntake = minIntake;
// Update weekly deficit based on the adjusted intake
var adjustedDailyDeficit = tdee – targetDailyIntake;
var adjustedWeeklyDeficit = adjustedDailyDeficit * 7;
weeklyDeficitRequired = adjustedWeeklyDeficit; // Update for display
dailyDeficitRequired = adjustedDailyDeficit; // Update for display
}

document.getElementById('bmrValue').textContent = bmr.toFixed(0) + ' kcal';
document.getElementById('tdeeValue').textContent = tdee.toFixed(0) + ' kcal';
document.getElementById('weeklyDeficitValue').textContent = weeklyDeficitRequired.toFixed(0) + ' kcal';
document.getElementById('mainResult').textContent = targetDailyIntake.toFixed(0) + ' kcal';

document.getElementById('resultsContainer').style.display = 'block';

updateChartAndTable(currentWeight, targetWeight, weightLossRate, tdee, targetDailyIntake);
}

function resetCalculator() {
document.getElementById('currentWeight').value = '75';
document.getElementById('targetWeight').value = '68';
document.getElementById('weightLossRate').value = '0.5';
document.getElementById('activityLevel').value = '1.725'; // Default to Very Active
document.getElementById('age').value = '30';
document.getElementById('gender').value = 'female';
document.getElementById('height').value = '170';

// Clear errors
document.getElementById('currentWeightError').textContent = '';
document.getElementById('currentWeightError').classList.remove('visible');
document.getElementById('targetWeightError').textContent = '';
document.getElementById('targetWeightError').classList.remove('visible');
document.getElementById('weightLossRateError').textContent = '';
document.getElementById('weightLossRateError').classList.remove('visible');
document.getElementById('activityLevelError').textContent = '';
document.getElementById('activityLevelError').classList.remove('visible');
document.getElementById('ageError').textContent = '';
document.getElementById('ageError').classList.remove('visible');
document.getElementById('genderError').textContent = '';
document.getElementById('genderError').classList.remove('visible');
document.getElementById('heightError').textContent = '';
document.getElementById('heightError').classList.remove('visible');

document.getElementById('resultsContainer').style.display = 'none';
if (chartInstance) {
chartInstance.destroy(); // Destroy previous chart
chartInstance = null;
}
document.getElementById('calorieTableBody').innerHTML = ''; // Clear table

// Re-initialize chart canvas if it was cleared
var canvas = document.getElementById('weightLossChart');
canvas.width = canvas.offsetWidth; // Reset canvas size if needed
canvas.height = 300; // Or a fixed height for consistency
generateChart([]); // Generate an empty chart
}

function copyResults() {
var bmr = document.getElementById('bmrValue').textContent;
var tdee = document.getElementById('tdeeValue').textContent;
var weeklyDeficit = document.getElementById('weeklyDeficitValue').textContent;
var mainResult = document.getElementById('mainResult').textContent;

var assumptions = [];
assumptions.push("Current Weight: " + document.getElementById('currentWeight').value + " kg");
assumptions.push("Target Weight: " + document.getElementById('targetWeight').value + " kg");
assumptions.push("Desired Weekly Loss: " + document.getElementById('weightLossRate').options[document.getElementById('weightLossRate').selectedIndex].text);
assumptions.push("Activity Level: " + document.getElementById('activityLevel').options[document.getElementById('activityLevel').selectedIndex].text);
assumptions.push("Age: " + document.getElementById('age').value);
assumptions.push("Gender: " + document.getElementById('gender').value);
assumptions.push("Height: " + document.getElementById('height').value + " cm");

var textToCopy = "Your Weight Loss Calorie Targets:\n";
textToCopy += "Target Daily Intake: " + mainResult + "\n";
textToCopy += "Basal Metabolic Rate (BMR): " + bmr + "\n";
textToCopy += "Total Daily Energy Expenditure (TDEE): " + tdee + "\n";
textToCopy += "Weekly Calorie Deficit: " + weeklyDeficit + "\n\n";
textToCopy += "Key Assumptions:\n" + assumptions.join('\n');

navigator.clipboard.writeText(textToCopy).then(function() {
alert('Results copied to clipboard!');
}).catch(function(err) {
console.error('Failed to copy text: ', err);
// Fallback for older browsers or if clipboard API is not available
var textArea = document.createElement("textarea");
textArea.value = textToCopy;
textArea.style.position = "fixed"; // Avoid scrolling to bottom
textArea.style.left = "-9999px";
textArea.style.top = "-9999px";
document.body.appendChild(textArea);
textArea.focus();
textArea.select();
try {
var successful = document.execCommand('copy');
var msg = successful ? 'successful' : 'unsuccessful';
console.log('Fallback: Copying text command was ' + msg);
} catch (err) {
console.error('Fallback: Oops, unable to copy', err);
}
document.body.removeChild(textArea);
alert('Results copied to clipboard (fallback method)!');
});
}

function updateChartAndTable(currentWeight, targetWeight, weightLossRate, tdee, targetDailyIntake) {
var tableBody = document.getElementById('calorieTableBody');
tableBody.innerHTML = ''; // Clear existing rows

var weightDifference = currentWeight – targetWeight;
var totalWeeksNeeded = Math.ceil(weightDifference / weightLossRate);

var chartLabels = [];
var chartData = [];
var chartDataTargetIntake = []; // Data series for target intake
var chartDataTDEE = []; // Data series for TDEE

var weeksToShow = Math.min(10, totalWeeksNeeded + 1); // Show up to 10 weeks or until target is met

for (var i = 0; i < weeksToShow; i++) {
var startWeight = currentWeight – (i * weightLossRate);
if (startWeight < targetWeight) startWeight = targetWeight; // Ensure weight doesn't go below target

var endWeight = startWeight – weightLossRate;
if (endWeight < targetWeight) endWeight = targetWeight;

var weekNum = i + 1;
var row = tableBody.insertRow();
row.insertCell(0).textContent = weekNum;
row.insertCell(1).textContent = startWeight.toFixed(1) + ' kg';
row.insertCell(2).textContent = targetDailyIntake.toFixed(0) + ' kcal';
row.insertCell(3).textContent = endWeight.toFixed(1) + ' kg';

chartLabels.push('Week ' + weekNum);
chartData.push(endWeight); // Use end weight for weight loss projection
chartDataTargetIntake.push(targetDailyIntake); // Target intake remains constant
chartDataTDEE.push(tdee); // TDEE might slightly decrease but for simplicity keep constant
}

// If target is reached within the shown weeks, add one more row for clarity
if (weeksToShow <= totalWeeksNeeded && weeksToShow < 10) {
var lastRowWeek = weeksToShow + 1;
var lastStartWeight = currentWeight – ((weeksToShow) * weightLossRate);
if (lastStartWeight < targetWeight) lastStartWeight = targetWeight;

var lastEndWeight = lastStartWeight – weightLossRate;
if (lastEndWeight < targetWeight) lastEndWeight = targetWeight;

var row = tableBody.insertRow();
row.insertCell(0).textContent = lastRowWeek;
row.insertCell(1).textContent = lastStartWeight.toFixed(1) + ' kg';
row.insertCell(2).textContent = targetDailyIntake.toFixed(0) + ' kcal';
row.insertCell(3).textContent = lastEndWeight.toFixed(1) + ' kg';

chartLabels.push('Week ' + lastRowWeek);
chartData.push(lastEndWeight);
chartDataTargetIntake.push(targetDailyIntake);
chartDataTDEE.push(tdee);
}

generateChart(chartLabels, chartData, chartDataTargetIntake, chartDataTDEE);
}

function generateChart(labels, weightData, targetIntakeData, tdeeData) {
var ctx = document.getElementById('weightLossChart').getContext('2d');

// Destroy previous chart instance if it exists
if (chartInstance) {
chartInstance.destroy();
}

// Ensure canvas dimensions are set correctly if they were reset
var canvas = document.getElementById('weightLossChart');
canvas.width = canvas.offsetWidth;
canvas.height = 300;

if (!labels || labels.length === 0) {
// Display a message or an empty chart if no data
ctx.font = "16px Segoe UI";
ctx.fillStyle = "#6c757d";
ctx.textAlign = "center";
ctx.fillText("Enter values to see the chart.", canvas.width / 2, canvas.height / 2);
return;
}

chartInstance = new Chart(ctx, {
type: 'line',
data: {
labels: labels,
datasets: [
{
label: 'Projected Weight (kg)',
data: weightData,
borderColor: 'var(–primary-color)',
backgroundColor: 'rgba(0, 74, 153, 0.1)',
fill: true,
tension: 0.3
},
{
label: 'Target Daily Intake (kcal)',
data: targetIntakeData,
borderColor: 'var(–success-color)',
borderDash: [5, 5],
fill: false,
tension: 0.3
},
{
label: 'Estimated TDEE (kcal)',
data: tdeeData,
borderColor: '#ffc107',
borderDash: [2, 2],
fill: false,
tension: 0.3
}
]
},
options: {
responsive: true,
maintainAspectRatio: false,
scales: {
y: {
beginAtZero: false,
title: {
display: true,
text: 'Weight (kg) / Calories (kcal)'
}
},
x: {
title: {
display: true,
text: 'Time'
}
}
},
plugins: {
title: {
display: true,
text: 'Weight Loss Projection',
font: {
size: 18
}
},
tooltip: {
mode: 'index',
intersect: false,
},
legend: {
position: 'top',
}
},
hover: {
mode: 'nearest',
intersect: true
}
}
});
}

// Initial setup to draw an empty chart or placeholder
document.addEventListener('DOMContentLoaded', function() {
// Set initial canvas dimensions
var canvas = document.getElementById('weightLossChart');
canvas.width = canvas.offsetWidth;
canvas.height = 300;
generateChart([]); // Generate an empty chart initially
});