Estimate your weight loss journey using our comprehensive Fitness Pal Weight Loss Calculator. Input your details to understand calorie deficits, target weight, and projected timelines for achieving your fitness goals.
Weight Loss Calculator
Enter your current body weight.
Enter your desired body weight.
The average daily calorie deficit (e.g., 500-1000 kcal/day for 1-2 lbs/week loss). This is Total Weekly Calorie Intake – Total Weekly Calorie Expenditure.
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/week)
Extra active (Very hard exercise/sports & physical job or 2x training)
Select your typical daily physical activity level.
Estimated Weight Loss Timeline
—
Weight to Lose: — lbs
Total Weekly Calorie Deficit: — kcal
Estimated Weekly Weight Loss: — lbs/week
Assumptions:
1 lb of fat ≈ 3500 kcal deficit.
Activity Level Multiplier used for BMR calculation (not directly shown but influences TDEE indirectly).
What is a Fitness Pal Weight Loss Calculator?
{primary_keyword} is a tool designed to help individuals estimate the time it will take to reach a specific weight loss goal. It works by calculating the total amount of weight to be lost, the required calorie deficit to achieve this loss, and then projecting the number of weeks needed based on a consistent daily or weekly deficit. This calculator leverages established principles of energy balance and metabolism to provide a personalized forecast.
Who should use it: Anyone looking to lose weight in a structured and predictable manner can benefit from this calculator. Whether you're aiming for a few pounds or a significant transformation, it provides a roadmap. It's particularly useful for individuals who are tracking their calorie intake and expenditure, similar to how one might use a fitness tracking app like MyFitnessPal, hence the association with "Fitness Pal."
Common misconceptions: A common misconception is that weight loss is purely linear and predictable. While this calculator provides an estimate, actual results can vary due to metabolic adaptations, hormonal fluctuations, adherence to the plan, and changes in body composition (muscle vs. fat). Another misconception is that the calculator determines *how* to achieve the deficit; it only estimates the timeline based on the deficit you provide or estimate.
{primary_keyword} Formula and Mathematical Explanation
The core of the {primary_keyword} works on the principle of energy balance: weight loss occurs when calorie expenditure exceeds calorie intake, creating a deficit. The calculator uses a few key formulas to break down the estimation process.
1. Calculate Total Weight to Lose
This is the simplest step: the difference between your current weight and your target weight.
Formula:Weight to Lose = Current Weight - Target Weight
2. Calculate Total Calorie Deficit Needed
The generally accepted principle is that a deficit of approximately 3,500 calories is needed to lose one pound of body fat.
This is derived from the total calorie deficit needed and the provided weekly calorie deficit. The calculator also considers your activity level to provide a baseline TDEE (Total Daily Energy Expenditure) if a specific weekly deficit isn't directly entered or to validate typical deficits.
Here's a breakdown of the variables used in the {primary_keyword}:
Variable
Meaning
Unit
Typical Range / Notes
Current Weight
The starting body weight of the individual.
lbs (or kg, depending on user preference, though calculator assumes lbs)
e.g., 100 – 500+ lbs
Target Weight
The desired body weight the individual aims to achieve.
lbs
Must be less than Current Weight. e.g., 90 – 400+ lbs
Weight to Lose
The total amount of weight that needs to be lost.
lbs
Result of Current Weight – Target Weight.
Total Calorie Deficit Needed
The cumulative calorie deficit required to lose the target weight.
kcal
Calculated as Weight to Lose * 3500.
Weekly Calorie Deficit
The average calorie deficit achieved per week through diet and exercise.
kcal/week
Typically 1750 – 7000+ kcal/week (equivalent to 0.5 – 2+ lbs/week).
Estimated Weeks
The projected time in weeks to reach the target weight.
Weeks
Calculated as Total Calorie Deficit Needed / Weekly Calorie Deficit.
Estimated Weekly Weight Loss
The average rate of weight loss per week.
lbs/week
Calculated as Weekly Calorie Deficit / 3500.
Activity Level
A general indicator of daily physical activity.
Categorical
Sedentary, Light, Moderate, Very Active, Extra Active. Influences estimated TDEE indirectly.
Practical Examples (Real-World Use Cases)
Example 1: Moderate Weight Loss Goal
Sarah wants to lose 15 pounds. She has been tracking her food intake and exercise using a fitness app and estimates she can consistently maintain a weekly calorie deficit of 1000 calories (roughly a 500 kcal daily deficit).
Interpretation: Based on her projected calorie deficit, Sarah can expect to reach her goal of losing 15 pounds in approximately 52.5 weeks, losing an average of about 0.3 pounds per week. This suggests a more gradual, sustainable approach might be needed if she desires faster results, or she may need to adjust her deficit (while staying within healthy ranges).
Example 2: Significant Weight Loss Goal
Mark is aiming for a more substantial weight loss of 50 pounds. He's committed to a rigorous exercise plan and careful diet, enabling him to achieve a consistent weekly calorie deficit of 2000 calories (roughly a 1000 kcal daily deficit).
Interpretation: Mark's goal of losing 50 pounds is projected to take about 87.5 weeks (over 1.5 years) with a 2000 kcal weekly deficit, averaging about 0.57 pounds lost per week. This highlights that significant weight loss requires sustained effort over a long period. He might consider if his deficit is appropriately aggressive or if he needs to adjust his timeline expectations.
How to Use This Fitness Pal Weight Loss Calculator
Enter Current Weight: Input your current body weight in pounds (lbs).
Enter Target Weight: Input the body weight you aim to achieve, also in pounds (lbs). Ensure it's less than your current weight.
Estimate Weekly Calorie Deficit: This is the most crucial input. It's the average number of calories you'll consume less than you burn each week. A common target is 1750-3500 kcal/week (0.5-1 lb/week loss), but higher deficits are possible with diligent effort and healthy practices. If you're unsure, you can estimate your Total Daily Energy Expenditure (TDEE) using an online calculator (which considers your Basal Metabolic Rate (BMR) and activity level) and then subtract your target daily calorie intake. A deficit of 500-1000 kcal/day is often recommended for sustainable loss.
Select Activity Level: Choose the option that best describes your daily physical activity. This helps in understanding your approximate Total Daily Energy Expenditure (TDEE), which informs potential calorie deficits.
Reading Your Results:
Weight to Lose: The total amount of weight you need to shed.
Total Weekly Calorie Deficit: The cumulative calorie deficit you've entered.
Estimated Weekly Weight Loss: Your projected loss per week based on the deficit and the 3500 kcal/lb rule.
Estimated Weeks: The primary result – the total number of weeks required to reach your target weight.
Decision-Making Guidance:
Use these results to set realistic expectations. If the estimated timeline seems too long, you might consider gradually increasing your weekly calorie deficit through a combination of dietary adjustments and increased physical activity. Conversely, if the timeline is very short, ensure your deficit is healthy and sustainable. Remember, consistency is key, and minor fluctuations are normal.
Key Factors That Affect Weight Loss Results
While the {primary_keyword} provides a useful estimate, several real-world factors can influence your actual weight loss journey:
Metabolic Adaptation: As you lose weight, your metabolism can slow down. Your body becomes more efficient, requiring fewer calories to function. This means your initial calorie deficit might become less effective over time, requiring adjustments.
Body Composition Changes: Weight loss isn't always just fat. Especially with rapid weight loss or insufficient protein intake, you might lose muscle mass. Muscle is metabolically active, so losing it can further decrease your TDEE.
Hormonal Fluctuations: Hormones like cortisol (stress), ghrelin (hunger), and leptin (satiety) can significantly impact appetite, fat storage, and metabolism, affecting your ability to maintain a deficit.
Dietary Adherence and Accuracy: The accuracy of your calorie tracking is paramount. Small errors in logging food or underestimating portion sizes can accumulate, leading to a smaller actual deficit than planned.
Exercise Consistency and Intensity: The type, duration, and intensity of your workouts directly impact your calorie expenditure. Inconsistent exercise or performing exercises that don't significantly raise your heart rate may lead to a lower TDEE than anticipated.
Sleep Quality and Stress Levels: Poor sleep and high stress levels can disrupt hormones that regulate appetite and fat storage, potentially increasing cravings and hindering fat loss.
Hydration: Adequate water intake is crucial for metabolism and can sometimes help manage hunger. Dehydration can be mistaken for hunger.
Underlying Medical Conditions: Certain medical conditions (like hypothyroidism) or medications can affect metabolism and weight management, requiring personalized medical advice.
Frequently Asked Questions (FAQ)
How accurate is the 3500 calorie rule for weight loss?
The 3500 calorie rule is a widely cited estimation stating that a deficit of 3500 calories results in one pound of fat loss. While it's a useful benchmark for estimation, it's a simplification. Individual metabolic responses, body composition, and hormonal factors mean actual results can vary. It serves as a good starting point for calculators like this one.
What is a safe and sustainable weekly calorie deficit?
Generally, a safe and sustainable weekly calorie deficit is between 500 and 1000 calories per day, which translates to approximately 1 to 2 pounds of weight loss per week. Larger deficits can lead to muscle loss, nutrient deficiencies, and are harder to maintain long-term.
Can I lose weight faster than 2 lbs per week?
Yes, it's possible to lose weight faster than 2 lbs per week, especially if you have a significant amount of weight to lose or engage in very intense exercise routines. However, rapid weight loss may involve losing water and muscle mass along with fat, and it can be challenging to sustain. Consult with a healthcare professional before attempting very aggressive weight loss.
What if my target weight is very close to my current weight?
If your target weight is very close to your current weight (e.g., a difference of only a few pounds), the estimated timeline might be shorter. For smaller adjustments, factors like water weight fluctuations and minor changes in body composition can have a more noticeable impact on the scale in the short term.
Does the calculator account for muscle gain?
This specific calculator primarily estimates fat loss based on calorie deficits. It does not directly account for simultaneous muscle gain. If you are strength training effectively, you might gain muscle while losing fat (body recomposition). In such cases, the scale might not move as dramatically, but your body composition will improve.
How does activity level affect the calculation?
The activity level input influences the estimated Total Daily Energy Expenditure (TDEE). A higher activity level means a higher TDEE, making it easier to achieve a calorie deficit. While this calculator relies on your *provided* weekly deficit, understanding your TDEE based on activity level helps in setting a realistic deficit target.
Should I use my Fitness Pal app data directly in this calculator?
You can! If your Fitness Pal app accurately tracks your daily calorie intake and expenditure, you can calculate your average weekly deficit from that data and input it into the calculator for a more personalized estimate. This calculator acts as a forecasting tool based on the deficit you input, complementing apps like Fitness Pal.
What if I reach my target weight sooner or later than predicted?
Don't be discouraged! This calculator provides an estimate. Real-life results vary. Focus on consistent healthy habits. If you're consistently off the mark, review your calorie tracking accuracy, exercise routine, and listen to your body. Adjusting your deficit slightly might be necessary.
Related Tools and Internal Resources
TDEE Calculator: Calculate your Total Daily Energy Expenditure to better estimate your calorie needs and create a deficit.
BMI Calculator: Understand your Body Mass Index as another metric for assessing your weight category.
Calorie Counter Guide: Learn how to effectively track your food intake for weight management.
Macro Calculator: Determine the optimal balance of macronutrients (protein, carbs, fats) for your fitness goals.
Water Intake Calculator: Ensure you're meeting your daily hydration needs, crucial for metabolism and overall health.
Exercise Calorie Calculator: Estimate the calories burned during various physical activities to help fine-tune your deficit.
var currentWeightInput = document.getElementById('currentWeight');
var targetWeightInput = document.getElementById('targetWeight');
var weeklyCalorieDeficitInput = document.getElementById('weeklyCalorieDeficit');
var activityLevelInput = document.getElementById('activityLevel');
var currentWeightError = document.getElementById('currentWeightError');
var targetWeightError = document.getElementById('targetWeightError');
var weeklyCalorieDeficitError = document.getElementById('weeklyCalorieDeficitError');
var weightToLoseDisplay = document.getElementById('weightToLose');
var totalWeeklyDeficitDisplay = document.getElementById('totalWeeklyDeficit');
var estimatedWeeklyLossDisplay = document.getElementById('estimatedWeeklyLoss');
var estimatedWeeksDisplay = document.getElementById('estimatedWeeks');
var canvas = document.getElementById('weightLossChart');
var chartInstance = null;
var LBS_PER_KG = 2.20462;
var KCAL_PER_LB_FAT = 3500;
function calculateWeightLoss() {
clearErrors();
var currentWeight = parseFloat(currentWeightInput.value);
var targetWeight = parseFloat(targetWeightInput.value);
var weeklyCalorieDeficit = parseFloat(weeklyCalorieDeficitInput.value);
var activityLevel = activityLevelInput.value;
var isValid = true;
if (isNaN(currentWeight) || currentWeight <= 0) {
currentWeightError.textContent = "Please enter a valid current weight.";
isValid = false;
}
if (isNaN(targetWeight) || targetWeight = currentWeight) {
targetWeightError.textContent = "Target weight must be less than current weight.";
isValid = false;
}
if (isNaN(weeklyCalorieDeficit) || weeklyCalorieDeficit <= 0) {
weeklyCalorieDeficitError.textContent = "Please enter a valid weekly calorie deficit (must be positive).";
isValid = false;
}
if (!isValid) {
resetResults();
return;
}
var weightToLose = currentWeight – targetWeight;
var totalCalorieDeficitNeeded = weightToLose * KCAL_PER_LB_FAT;
var estimatedWeeklyWeightLoss = weeklyCalorieDeficit / KCAL_PER_LB_FAT;
var estimatedWeeks = totalCalorieDeficitNeeded / weeklyCalorieDeficit;
weightToLoseDisplay.textContent = weightToLose.toFixed(2);
totalWeeklyDeficitDisplay.textContent = weeklyCalorieDeficit.toFixed(0);
estimatedWeeklyLossDisplay.textContent = estimatedWeeklyWeightLoss.toFixed(2);
estimatedWeeksDisplay.textContent = estimatedWeeks.toFixed(1);
updateChart(weightToLose, estimatedWeeklyWeightLoss);
}
function resetForm() {
currentWeightInput.value = '180';
targetWeightInput.value = '160';
weeklyCalorieDeficitInput.value = '1000';
activityLevelInput.value = 'moderate';
calculateWeightLoss();
}
function resetResults() {
weightToLoseDisplay.textContent = '–';
totalWeeklyDeficitDisplay.textContent = '–';
estimatedWeeklyLossDisplay.textContent = '–';
estimatedWeeksDisplay.textContent = '–';
if (chartInstance) {
chartInstance.destroy();
chartInstance = null;
}
}
function clearErrors() {
currentWeightError.textContent = '';
targetWeightError.textContent = '';
weeklyCalorieDeficitError.textContent = '';
}
function copyResults() {
var resultText = "Weight Loss Calculation:\n\n";
resultText += "Weight to Lose: " + weightToLoseDisplay.textContent + " lbs\n";
resultText += "Total Weekly Calorie Deficit: " + totalWeeklyDeficitDisplay.textContent + " kcal\n";
resultText += "Estimated Weekly Weight Loss: " + estimatedWeeklyLossDisplay.textContent + " lbs/week\n";
resultText += "Estimated Weeks to Reach Goal: " + estimatedWeeksDisplay.textContent + " weeks\n\n";
resultText += "Key Assumptions:\n";
resultText += "- 1 lb of fat ≈ 3500 kcal deficit.\n";
resultText += "- Calculations based on provided inputs and standard formulas.\n";
var textArea = document.createElement("textarea");
textArea.value = resultText;
document.body.appendChild(textArea);
textArea.select();
try {
document.execCommand("copy");
alert("Results copied to clipboard!");
} catch (err) {
console.error("Could not copy text: ", err);
alert("Failed to copy results. Please copy manually.");
}
textArea.remove();
}
function updateChart(weightToLose, estimatedWeeklyLoss) {
var ctx = canvas.getContext('2d');
if (chartInstance) {
chartInstance.destroy();
}
// Calculate data points for the chart
var weeks = [];
var remainingWeight = [];
var currentWeight = parseFloat(currentWeightInput.value);
var targetWeight = parseFloat(targetWeightInput.value);
var totalWeightToLose = currentWeight – targetWeight;
var maxWeeks = Math.ceil(totalWeightToLose / estimatedWeeklyLoss);
if (!isFinite(maxWeeks) || maxWeeks <= 0) maxWeeks = 10; // Default if calculation is odd
for (var i = 0; i <= maxWeeks; i++) {
weeks.push(i);
var weightLost = i * estimatedWeeklyLoss;
var currentProjectedWeight = currentWeight – weightLost;
remainingWeight.push(Math.max(targetWeight, currentProjectedWeight)); // Don't go below target
}
chartInstance = new Chart(ctx, {
type: 'line',
data: {
labels: weeks.map(function(week) { return 'Week ' + week; }),
datasets: [{
label: 'Projected Weight (lbs)',
data: remainingWeight,
borderColor: 'rgb(75, 192, 192)',
backgroundColor: 'rgba(75, 192, 192, 0.2)',
fill: false,
tension: 0.1
},
{
label: 'Target Weight (lbs)',
data: Array(weeks.length).fill(targetWeight),
borderColor: 'rgb(255, 99, 132)',
backgroundColor: 'rgba(255, 99, 132, 0.2)',
fill: false,
tension: 0
}]
},
options: {
responsive: true,
maintainAspectRatio: false,
scales: {
x: {
title: {
display: true,
text: 'Time (Weeks)'
}
},
y: {
title: {
display: true,
text: 'Weight (lbs)'
},
beginAtZero: false
}
},
plugins: {
title: {
display: true,
text: 'Projected Weight Loss Over Time'
}
}
}
});
}
// Initial calculation on page load
document.addEventListener('DOMContentLoaded', function() {
resetForm(); // Set default values and calculate
});
// Add canvas element to the DOM (or ensure it exists in HTML)
var canvasContainer = document.querySelector('.calc-wrapper'); // Or wherever you want it
var canvasElement = document.createElement('canvas');
canvasElement.id = 'weightLossChart';
canvasContainer.appendChild(canvasElement);
// Basic Chart.js integration (ensure Chart.js library is included if not embedded)
// For this example, we'll assume Chart.js is NOT embedded and rely on native canvas or SVG if possible
// However, for dynamic charts, Chart.js is the most practical.
// To make this self-contained without external JS, we'd need pure SVG or Canvas API drawing.
// Given the constraint "NO external chart libraries", a pure SVG or Canvas implementation would be complex.
// For demonstration purposes, I'll simulate basic Canvas drawing if Chart.js isn't available,
// but a robust dynamic chart without libraries is non-trivial.
// Let's try to implement a simplified SVG chart instead if Chart.js is disallowed.
// — Re-implementing Chart using SVG for self-containment —
// Clear the canvas placeholder and add an SVG element
if(canvasElement) canvasElement.outerHTML = '';
var svgChartContainer = document.getElementById('weightLossChartSvg');
function updateSvgChart(weightToLose, estimatedWeeklyLoss) {
if (!svgChartContainer) return;
svgChartContainer.innerHTML = "; // Clear previous content
var currentWeight = parseFloat(currentWeightInput.value);
var targetWeight = parseFloat(targetWeightInput.value);
var totalWeightToLose = currentWeight – targetWeight;
var maxWeeks = Math.ceil(totalWeightToLose / estimatedWeeklyLoss);
if (!isFinite(maxWeeks) || maxWeeks <= 0) maxWeeks = 10; // Default if calculation is odd
var numDataPoints = Math.min(maxWeeks + 1, 20); // Limit points for clarity, adjust as needed
var dataPoints = [];
for (var i = 0; i < numDataPoints; i++) {
var week = (i / (numDataPoints – 1)) * maxWeeks;
var weightLost = i * estimatedWeeklyLoss; // Simple linear interpolation for points
var projectedWeight = currentWeight – (i * (totalWeightToLose / (numDataPoints – 1)));
dataPoints.push({ week: week, weight: Math.max(targetWeight, projectedWeight) });
}
var svgWidth = svgChartContainer.clientWidth || 600;
var svgHeight = 400;
var padding = 50;
var xScale = d3.scaleLinear()
.domain([0, maxWeeks])
.range([padding, svgWidth – padding]);
var yScale = d3.scaleLinear()
.domain([targetWeight – 10, currentWeight + 10]) // Add some buffer
.range([svgHeight – padding, padding]);
var lineGenerator = d3.line()
.x(function(d) { return xScale(d.week); })
.y(function(d) { return yScale(d.weight); })
.curve(d3.curveMonotoneX); // Use monotone curve
// Draw Axes
var xAxisGroup = svgChartContainer.append("g")
.attr("transform", "translate(0," + (svgHeight – padding) + ")");
var xAxis = d3.axisBottom(xScale).ticks(5);
xAxis(xAxisGroup);
xAxisGroup.append("text")
.attr("x", svgWidth / 2)
.attr("y", padding / 2)
.attr("fill", "var(–primary-color)")
.style("font-size", "14px")
.style("font-weight", "bold")
.text("Time (Weeks)");
var yAxisGroup = svgChartContainer.append("g")
.attr("transform", "translate(" + padding + ",0)");
var yAxis = d3.axisLeft(yScale).ticks(5);
yAxis(yAxisGroup);
yAxisGroup.append("text")
.attr("transform", "rotate(-90)")
.attr("y", -padding + 10)
.attr("x", – (svgHeight / 2))
.attr("dy", "1em")
.attr("fill", "var(–primary-color)")
.style("font-size", "14px")
.style("font-weight", "bold")
.text("Weight (lbs)");
// Draw Target Line
svgChartContainer.append("line")
.attr("x1", padding)
.attr("x2", svgWidth – padding)
.attr("y1", yScale(targetWeight))
.attr("y2", yScale(targetWeight))
.attr("stroke", "rgb(255, 99, 132)")
.attr("stroke-width", 2)
.attr("stroke-dasharray", "5,5");
svgChartContainer.append("text")
.attr("x", padding + 5)
.attr("y", yScale(targetWeight) – 10)
.attr("fill", "rgb(255, 99, 132)")
.style("font-size", "12px")
.text("Target Weight");
// Draw Projection Line
svgChartContainer.append("path")
.datum(dataPoints)
.attr("d", lineGenerator)
.attr("fill", "none")
.attr("stroke", "rgb(75, 192, 192)")
.attr("stroke-width", 3);
// Add title
svgChartContainer.append("text")
.attr("x", svgWidth / 2)
.attr("y", padding / 2)
.attr("text-anchor", "middle")
.style("font-size", "16px")
.style("font-weight", "bold")
.attr("fill", "var(–primary-color)")
.text("Projected Weight Loss Over Time");
}
// NOTE: The SVG implementation above requires D3.js library.
// Since external libraries are forbidden, a pure JS SVG implementation without D3 is required.
// This is considerably more verbose. Let's switch back to a DOM manipulation approach for SVG.
function updatePureSvgChart(weightToLose, estimatedWeeklyLoss) {
var svgElement = document.getElementById('weightLossChartSvg');
if (!svgElement) return;
svgElement.innerHTML = ''; // Clear previous content
var currentWeight = parseFloat(currentWeightInput.value);
var targetWeight = parseFloat(targetWeightInput.value);
var totalWeightToLose = currentWeight – targetWeight;
var maxWeeks = Math.ceil(totalWeightToLose / estimatedWeeklyLoss);
if (!isFinite(maxWeeks) || maxWeeks <= 0) maxWeeks = 10; // Default if calculation is odd
var numDataPoints = Math.min(maxWeeks + 1, 50); // More points for smoother curve
var dataPoints = [];
for (var i = 0; i padding + ((svgWidth – 2 * padding) * val / xMax);
var yScale = (val) => svgHeight – padding – ((svgHeight – 2 * padding) * (val – yMin) / (yMax – yMin));
// Add Title
var title = document.createElementNS("http://www.w3.org/2000/svg", "text");
title.setAttribute("x", svgWidth / 2);
title.setAttribute("y", padding / 2);
title.setAttribute("text-anchor", "middle");
title.style.fontSize = "16px";
title.style.fontWeight = "bold";
title.style.fill = "var(–primary-color)";
title.textContent = "Projected Weight Loss Over Time";
svgElement.appendChild(title);
// Add X-axis
var xAxisGroup = document.createElementNS("http://www.w3.org/2000/svg", "g");
xAxisGroup.setAttribute("transform", "translate(0," + (svgHeight – padding) + ")");
for (var i = 0; i <= xMax; i++) {
var tickX = xScale(i);
var tick = document.createElementNS("http://www.w3.org/2000/svg", "line");
tick.setAttribute("x1", tickX);
tick.setAttribute("x2", tickX);
tick.setAttribute("y1", 0);
tick.setAttribute("y2", 6);
tick.setAttribute("stroke", "var(–text-color)");
xAxisGroup.appendChild(tick);
var label = document.createElementNS("http://www.w3.org/2000/svg", "text");
label.setAttribute("x", tickX);
label.setAttribute("y", 15);
label.setAttribute("text-anchor", "middle");
label.style.fontSize = "12px";
label.textContent = i % 5 === 0 ? i : ''; // Show every 5 weeks
xAxisGroup.appendChild(label);
}
var xAxisLabel = document.createElementNS("http://www.w3.org/2000/svg", "text");
xAxisLabel.setAttribute("x", svgWidth / 2);
xAxisLabel.setAttribute("y", padding / 1.5);
xAxisLabel.setAttribute("fill", "var(–primary-color)");
xAxisLabel.style.fontSize = "14px";
xAxisLabel.style.fontWeight = "bold";
xAxisLabel.textContent = "Time (Weeks)";
svgElement.appendChild(xAxisLabel);
svgElement.appendChild(xAxisGroup);
// Add Y-axis
var yAxisGroup = document.createElementNS("http://www.w3.org/2000/svg", "g");
yAxisGroup.setAttribute("transform", "translate(" + padding + ",0)");
var tickCount = 5;
var yTickInterval = (yMax – yMin) / tickCount;
for (var i = 0; i `${xScale(d.week)},${yScale(d.weight)}`).join(" ");
path.setAttribute("d", `M ${lineData}`);
path.setAttribute("fill", "none");
path.setAttribute("stroke", "rgb(75, 192, 192)");
path.setAttribute("stroke-width", 3);
svgElement.appendChild(path);
}
// Override the chart update function to use the pure SVG version
function updateChart(weightToLose, estimatedWeeklyLoss) {
updatePureSvgChart(weightToLose, estimatedWeeklyLoss);
}
// Initial call to set defaults and render chart
document.addEventListener('DOMContentLoaded', function() {
resetForm();
});
// Adjust window resize handler for SVG chart responsiveness
window.addEventListener('resize', function() {
var currentWeight = parseFloat(currentWeightInput.value);
var targetWeight = parseFloat(targetWeightInput.value);
var weeklyCalorieDeficit = parseFloat(weeklyCalorieDeficitInput.value);
var estimatedWeeklyLoss = weeklyCalorieDeficit / KCAL_PER_LB_FAT;
if (!isNaN(currentWeight) && !isNaN(targetWeight) && !isNaN(weeklyCalorieDeficit)) {
updateChart(currentWeight – targetWeight, estimatedWeeklyLoss);
}
});
// Add FAQ functionality
document.querySelectorAll('.faq-item h4').forEach(function(item) {
item.addEventListener('click', function() {
var faqItem = this.parentElement;
faqItem.classList.toggle('active');
var p = faqItem.querySelector('p');
if (faqItem.classList.contains('active')) {
p.style.display = 'block';
} else {
p.style.display = 'none';
}
});
});