Calculate Your Optimal Daily Protein Intake for Muscle Growth
Protein Intake Calculator
Enter your current body weight in kilograms (kg).
Sedentary (little to 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)
Select your general daily activity level.
Muscle Gain
Lean Mass Gain
General Weight Gain
Choose your primary weight gain objective.
Your Protein Intake Results
— g/day
Recommended Range (Low): — g/day
Recommended Range (High): — g/day
Protein per Kg of Body Weight: — g/kg/day
Formula Used
The recommended daily protein intake for weight gain, especially muscle gain, depends on body weight, activity level, and the specific goal. Generally, individuals aiming for muscle hypertrophy require more protein. The ranges provided are based on established nutritional guidelines, typically from 1.6 to 2.2 grams of protein per kilogram of body weight per day for active individuals and those seeking to build muscle.
Key Assumptions
Body weight is accurate.
Activity level is correctly represented.
The goal of "Muscle Gain" or "Lean Mass Gain" implies a focus on hypertrophy.
Individual metabolic rates and dietary needs may vary.
Protein Intake Over Time (Estimated)
Estimated daily protein intake range for muscle gain over a 12-week period.
Protein Intake vs. Body Weight
Protein Intake vs. Body Weight
Body Weight (kg)
Protein Intake (g/day)
Visual representation of how protein intake scales with body weight.
Example Scenarios
Scenario Description
Body Weight (kg)
Activity Level
Goal
Est. Daily Protein (g)
Protein per Kg (g/kg)
Beginner Lifter
70
Moderately Active
Muscle Gain
140 – 154
2.0 – 2.2
Advanced Athlete
85
Very Active
Lean Mass Gain
170 – 187
2.0 – 2.2
Weight Gainer
65
Lightly Active
General Weight Gain
104 – 117
1.6 – 1.8
What is a Protein Weight Gain Calculator?
A protein weight gain calculator is an online tool designed to estimate the optimal daily protein intake required for individuals aiming to gain weight, particularly muscle mass. It takes into account key personal factors such as current body weight, activity level, and specific weight gain goals (like muscle gain or lean mass gain). The primary function of such a calculator is to simplify complex nutritional science into actionable recommendations, helping users understand how much protein they should consume to support their body composition objectives.
Who Should Use It?
This calculator is beneficial for a wide range of individuals, including:
Athletes and bodybuilders looking to maximize muscle hypertrophy.
Individuals undergoing strength training programs.
People seeking to increase their overall body weight in a healthy manner, focusing on muscle rather than just fat.
Anyone interested in understanding their protein needs for recovery and growth after exercise.
Nutrition enthusiasts aiming to fine-tune their dietary intake for specific fitness goals.
Common Misconceptions
Several myths surround protein intake for weight gain:
Myth: More protein is always better. While protein is crucial, excessive intake doesn't necessarily lead to proportionally greater muscle gains and can strain kidneys if hydration is poor. The calculator provides a targeted range.
Myth: Protein alone causes weight gain. Weight gain, especially muscle gain, requires a caloric surplus (eating more calories than you burn) alongside adequate protein and resistance training. Protein is a building block, not the sole driver.
Myth: Protein supplements are essential. Whole food sources can adequately meet protein needs. Supplements are convenient but not mandatory. This tool focuses on total daily intake, regardless of source.
Protein Weight Gain Calculator Formula and Mathematical Explanation
The core of the protein weight gain calculator relies on established scientific recommendations for protein intake, often expressed in grams per kilogram of body weight per day (g/kg/day). The specific multiplier used within the calculator is adjusted based on the user's selected activity level and weight gain goal.
Step-by-Step Derivation
Base Calculation: The calculator starts with the user's body weight in kilograms.
Multiplier Determination: Based on the user's selected Activity Level and Weight Gain Goal, a specific protein intake range (as a multiplier) is applied.
Range Calculation:
The lower end of the protein range is calculated by multiplying body weight by the lower recommended multiplier for that category.
The higher end of the protein range is calculated by multiplying body weight by the higher recommended multiplier.
Primary Result: Often, the calculator will highlight a specific value within this range, typically around the middle or upper end, emphasizing sufficient intake for muscle growth.
Variable Explanations
Body Weight: The user's current weight, the primary factor determining absolute protein needs.
Activity Level: Indicates the user's energy expenditure and muscle repair requirements. Higher activity means higher needs.
Weight Gain Goal: Differentiates between general weight gain, muscle-focused gain, or lean mass gain, influencing the recommended protein intensity.
Variables Table
Variable
Meaning
Unit
Typical Range (for Weight Gain)
Body Weight
Current mass of the individual
kg
40 – 150+
Activity Level Factor
Multiplier based on exercise frequency and intensity
N/A (Categorical)
Sedentary, Lightly Active, Moderately Active, Very Active, Extra Active
Goal Factor
Adjustment for specific weight gain objective
N/A (Categorical)
Muscle Gain, Lean Mass Gain, General Weight Gain
Protein Intake
Estimated daily protein requirement
grams/day (g/day)
100 – 300+
Protein per Kg
Protein requirement relative to body mass
grams/kilogram/day (g/kg/day)
1.6 – 2.2
Note: The 'typical range' for Protein Intake and Protein per Kg are influenced by the specific inputs of Body Weight, Activity Level, and Goal.
Practical Examples (Real-World Use Cases)
Understanding how the protein weight gain calculator works is best illustrated with practical examples:
Example 1: The Dedicated Bodybuilder
Inputs:
Body Weight: 80 kg
Activity Level: Very Active (5-6 days/week intense weight training)
Weight Gain Goal: Muscle Gain
Calculation: For a very active individual aiming for muscle gain, the recommended protein intake is typically between 1.8 and 2.2 g/kg/day.
Low Estimate: 80 kg * 1.8 g/kg/day = 144 g/day
High Estimate: 80 kg * 2.2 g/kg/day = 176 g/day
Calculator Output: The calculator would likely show a range of 144-176 g/day, with a primary recommendation around 160 g/day.
Interpretation: This individual needs a substantial protein intake to support muscle repair and growth driven by their intense training regimen and caloric surplus necessary for weight gain.
Example 2: The Active Student
Inputs:
Body Weight: 65 kg
Activity Level: Moderately Active (attends gym 3-4 times a week, plus daily walking)
Weight Gain Goal: General Weight Gain (aiming for a healthier weight)
Calculation: For a moderately active person with a general weight gain goal, the range might be slightly lower, perhaps 1.4 to 1.8 g/kg/day.
Low Estimate: 65 kg * 1.4 g/kg/day = 91 g/day
High Estimate: 65 kg * 1.8 g/kg/day = 117 g/day
Calculator Output: The calculator would suggest a range of approximately 91-117 g/day, possibly highlighting 105 g/day.
Interpretation: This individual requires adequate protein to support muscle maintenance and growth during their workouts, alongside sufficient overall calories for healthy weight gain, but perhaps less intensely than a competitive bodybuilder.
Example 3: The Endurance Athlete
Inputs:
Body Weight: 72 kg
Activity Level: Extra Active (daily long runs/cycles, physically demanding job)
Weight Gain Goal: Lean Mass Gain (focusing on muscle without excess fat)
Calculation: Endurance athletes, especially those aiming for lean mass, benefit from protein for muscle repair and preventing muscle breakdown, typically in the 1.6 to 2.0 g/kg/day range.
Low Estimate: 72 kg * 1.6 g/kg/day = 115.2 g/day
High Estimate: 72 kg * 2.0 g/kg/day = 144 g/day
Calculator Output: The calculator would recommend a range of approximately 115-144 g/day, with a focus around 130 g/day.
Interpretation: While prioritizing carbohydrates for energy, this athlete still needs significant protein to aid recovery from high-volume training and preserve muscle tissue during caloric intake adjustments for lean gain.
How to Use This Protein Weight Gain Calculator
Using the protein weight gain calculator is straightforward. Follow these steps to get your personalized protein intake recommendation:
Step-by-Step Instructions
Enter Body Weight: Input your current weight accurately in kilograms (kg) into the 'Body Weight' field.
Select Activity Level: Choose the option that best describes your typical weekly exercise routine and daily physical activity from the 'Activity Level' dropdown menu. Be honest about your intensity and frequency.
Choose Your Goal: Select your primary objective from the 'Weight Gain Goal' dropdown. Whether you're aiming for pure muscle, lean mass, or general weight increase impacts the protein recommendation.
View Results: Once you've entered the information, the calculator will instantly update to display your recommended daily protein intake range and a specific target value.
Understand the Metrics: Pay attention to the main highlighted result (your target daily grams of protein) and the intermediate values, including the recommended range and protein per kilogram of body weight.
How to Read Results
Main Result (g/day): This is your primary target for daily protein consumption to support your stated weight gain goals.
Recommended Range (Low/High): This range provides flexibility. Consuming within this spectrum is generally considered beneficial. Some may aim for the lower end, others for the higher, depending on individual response and dietary preferences.
Protein per Kg of Body Weight (g/kg/day): This metric contextualizes your needs relative to your body size, offering another way to understand the recommendation.
Assumptions: Review the key assumptions to understand the basis of the calculation and potential limitations.
Decision-Making Guidance
Use these results as a guideline, not a rigid rule. Integrate this protein target into your daily meal planning. Aim to spread your protein intake throughout the day, consuming protein-rich foods with each meal and snack. Remember that a caloric surplus is necessary for weight gain. This calculator focuses solely on the protein component, which is vital for ensuring that the weight gained is primarily muscle mass.
Key Factors That Affect Protein Weight Gain Results
While the protein weight gain calculator provides a solid estimate, several real-world factors can influence the optimal protein intake and the success of your weight gain journey:
Caloric Intake: This is paramount. Weight gain, including muscle gain, requires consuming more calories than you burn (a caloric surplus). Without this surplus, even optimal protein intake won't lead to weight gain. The calculator assumes a sufficient caloric intake is in place.
Training Stimulus: Resistance training is the primary signal for muscle protein synthesis. If you're not engaging in effective strength training, your body won't prioritize building muscle, regardless of protein intake. The calculator's 'Activity Level' factor accounts for training, but the *quality* and *progression* of your training matter immensely.
Macronutrient Distribution: Protein is just one part of the equation. Adequate carbohydrates are needed to fuel workouts and replenish glycogen stores, while healthy fats are essential for hormone production. An imbalanced intake of other macros can hinder progress.
Protein Quality and Timing: Not all protein sources are equal. Complete proteins (containing all essential amino acids) are best for muscle building. While total daily intake is key, some research suggests spreading protein intake across meals (e.g., 20-40g per meal) may optimize muscle protein synthesis.
Recovery and Sleep: Muscle growth occurs during rest, not during training. Insufficient sleep impairs muscle recovery and hormonal balance (like testosterone and growth hormone), negatively impacting muscle gain potential.
Age and Hormonal Profile: Protein synthesis efficiency and hormonal responses can change with age. Younger individuals or those with optimal hormonal levels may build muscle more readily than older individuals or those with hormonal deficiencies.
Genetics: Individual genetic makeup plays a significant role in how efficiently one builds muscle and gains weight. Some people are naturally predisposed to lean gains, while others gain muscle and fat more easily.
Hydration: Adequate water intake is crucial for overall metabolic function, nutrient transport, and kidney health, especially when consuming higher protein amounts. Dehydration can impair performance and recovery.
Frequently Asked Questions (FAQ)
Q1: How much protein do I need daily for weight gain if I'm not exercising?
A: If your goal is general weight gain without exercise, your protein needs are lower but still important for basic bodily functions and preventing muscle loss. Aiming for the lower end of the general range, perhaps 1.0-1.4 g/kg of body weight, might suffice, alongside a caloric surplus. The calculator defaults to higher ranges for active individuals, so select 'Sedentary' if applicable.
Q2: Is 2.2g of protein per kg of body weight too much?
A: For most active individuals aiming for significant muscle gain, 2.2 g/kg is considered the upper end of the effective range. Consuming more than this generally doesn't yield additional muscle-building benefits and may be unnecessary unless under specific, intense training conditions or physician guidance. The calculator provides this range based on research.
Q3: Can I reach my weight gain goals with only 1.6g/kg of protein?
A: Yes, for many individuals, especially those who are not training with extreme intensity or volume, 1.6 g/kg of body weight is sufficient to support muscle protein synthesis and muscle gain, provided there is a consistent caloric surplus and appropriate resistance training stimulus. The calculator offers a range to accommodate different needs.
Q4: Should I prioritize protein over carbs and fats for weight gain?
A: For weight gain, especially muscle gain, a caloric surplus is the primary driver. While protein is critical for building muscle tissue, carbohydrates are essential for energy to fuel intense workouts and replenish glycogen stores. Fats are vital for hormone production. Aim for a balanced intake of all macronutrients, with protein typically constituting 1.6-2.2 g/kg/day, and the remainder of calories coming from carbs and fats.
Q5: What are the best protein sources for weight gain?
A: Excellent sources include lean meats (chicken, turkey, beef), fish (salmon, tuna), eggs, dairy products (Greek yogurt, cottage cheese, milk), legumes (beans, lentils), tofu, and protein powders (whey, casein, soy, plant-based blends). Variety ensures a full spectrum of amino acids and other nutrients.
Q6: How long does it take to see results from increased protein intake?
A: Muscle growth is a gradual process. While you might feel stronger or recover better within weeks, noticeable visual changes in muscle size typically take months of consistent training, adequate nutrition (including protein and calories), and sufficient rest. The calculator provides daily targets, but results are long-term.
Q7: Does the calculator account for intermittent fasting?
A: The calculator estimates total daily protein needs. How you structure your eating window (e.g., during intermittent fasting) doesn't change the total amount of protein required per day for muscle growth. You'll need to ensure your protein target is met within your eating periods, often by consuming larger, protein-dense meals.
Q8: Should I adjust my protein intake if I have kidney issues?
A: Individuals with pre-existing kidney conditions should consult with a healthcare professional or registered dietitian before significantly increasing protein intake. While high protein intake is generally safe for healthy kidneys, those with compromised kidney function may need specific dietary recommendations.
Weight gain goal: ${goal.replace('_', ' ').replace(/\b\w/g, char => char.toUpperCase())}
Recommended protein range: ${Math.round(calculatedProteinRangeLow)} – ${Math.round(calculatedProteinRangeHigh)} g/day
This equates to ${calculatedGramsPerKg.toFixed(1)} g/kg/day on average.
Individual needs may vary based on metabolism, training intensity, and other health factors.
`;
// Prepare data for charts
chartData = {
target: mainResultValue,
rangeLow: calculatedProteinRangeLow,
rangeHigh: calculatedProteinRangeHigh
};
updateCharts();
}
function resetResults() {
document.getElementById("resultsContainer").innerHTML = `
— g/day
Recommended Range (Low): — g/day
Recommended Range (High): — g/day
Protein per Kg of Body Weight: — g/kg/day
Formula Used
The recommended daily protein intake for weight gain, especially muscle gain, depends on body weight, activity level, and the specific goal. Generally, individuals aiming for muscle hypertrophy require more protein. The ranges provided are based on established nutritional guidelines, typically from 1.6 to 2.2 grams of protein per kilogram of body weight per day for active individuals and those seeking to build muscle.
Key Assumptions
Body weight is accurate.
Activity level is correctly represented.
The goal of "Muscle Gain" or "Lean Mass Gain" implies a focus on hypertrophy.
Individual metabolic rates and dietary needs may vary.
`;
document.getElementById("proteinIntakeChart").getContext('2d').clearRect(0, 0, canvas.width, canvas.height); // Clear canvas
updateCharts(); // Update to show default state if needed
}
function resetCalculator() {
document.getElementById("bodyWeight").value = "";
document.getElementById("activityLevel").value = "moderately_active";
document.getElementById("goal").value = "muscle_gain";
document.getElementById("bodyWeightError").textContent = "";
resetResults();
}
function copyResults() {
var mainResultEl = document.getElementById("mainResult");
var proteinRangeLowEl = document.getElementById("proteinRangeLow");
var proteinRangeHighEl = document.getElementById("proteinRangeHigh");
var gramsPerKgEl = document.getElementById("gramsPerKg");
var assumptionsListEl = document.getElementById("assumptionsList");
var mainResultText = mainResultEl.textContent.replace("– g/day", "N/A");
var rangeText = proteinRangeLowEl.textContent.replace("Recommended Range (Low): ", "") + " – " + proteinRangeHighEl.textContent.replace("Recommended Range (High): ", "");
var gramsPerKgText = gramsPerKgEl.textContent.replace("Protein per Kg of Body Weight: ", "");
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var listItems = assumptionsListEl.getElementsByTagName('li');
for (var i = 0; i < listItems.length; i++) {
assumptions.push("- " + listItems[i].textContent.trim());
}
var assumptionsText = assumptions.join("\n");
var textToCopy = `Protein Intake Results:\n\n` +
`Target Daily Protein: ${mainResultText}\n` +
`Recommended Range: ${rangeText}\n` +
`${gramsPerKgText}\n\n` +
`Key Assumptions:\n${assumptionsText}`;
// Use navigator.clipboard if available, otherwise fallback
if (navigator.clipboard && navigator.clipboard.writeText) {
navigator.clipboard.writeText(textToCopy).then(function() {
alert('Results copied to clipboard!');
}).catch(function(err) {
console.error('Failed to copy text: ', err);
fallbackCopyTextToClipboard(textToCopy);
});
} else {
fallbackCopyTextToClipboard(textToCopy);
}
}
function fallbackCopyTextToClipboard(text) {
var textArea = document.createElement("textarea");
textArea.value = text;
textArea.style.position = "fixed";
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);
alert('Results copied to clipboard!');
} catch (err) {
console.error('Fallback: Oops, unable to copy', err);
alert('Failed to copy results. Please copy manually.');
}
document.body.removeChild(textArea);
}
// — Charting —
var proteinIntakeChartInstance = null; // To hold the chart instance
function updateCharts() {
if (!document.getElementById("proteinIntakeChart")) return; // Exit if canvas element is not present
var ctx = document.getElementById("proteinIntakeChart").getContext('2d');
// Clear previous chart if it exists
if (proteinIntakeChartInstance) {
proteinIntakeChartInstance.destroy();
}
// Prepare data
var targetProtein = parseFloat(document.getElementById("mainResult").textContent.replace(" g/day", "")) || 0;
var rangeLow = parseFloat(document.getElementById("proteinRangeLow").textContent.replace("Recommended Range (Low): ", "").replace(" g/day", "")) || 0;
var rangeHigh = parseFloat(document.getElementById("proteinRangeHigh").textContent.replace("Recommended Range (High): ", "").replace(" g/day", "")) || 0;
// Simulate data for 12 weeks
var weeks = [];
var targetSeries = [];
var lowerRangeSeries = [];
var upperRangeSeries = [];
var weekCount = 12;
for (var i = 0; i < weekCount; i++) {
weeks.push("Week " + (i + 1));
targetSeries.push(targetProtein);
lowerRangeSeries.push(rangeLow);
upperRangeSeries.push(rangeHigh);
}
proteinIntakeChartInstance = new Chart(ctx, {
type: 'line',
data: {
labels: weeks,
datasets: [{
label: 'Target Protein Intake',
data: targetSeries,
borderColor: '#004a99',
backgroundColor: 'rgba(0, 74, 153, 0.1)',
fill: false, // Don't fill under the line for target
tension: 0.4
}, {
label: 'Protein Intake Range',
data: lowerRangeSeries, // Use lower range for start of fill
borderColor: 'rgba(40, 167, 69, 0.5)',
backgroundColor: 'rgba(40, 167, 69, 0.2)', // Light green fill
fill: '+1', // Fills between this dataset and the one after it (upperRangeSeries)
tension: 0.4
}, {
label: 'Upper Range', // This dataset is mainly for the fill calculation
data: upperRangeSeries,
borderColor: 'rgba(40, 167, 69, 0)', // Invisible border
backgroundColor: 'rgba(40, 167, 69, 0)', // Invisible background
fill: false
}]
},
options: {
responsive: true,
maintainAspectRatio: false,
scales: {
x: {
title: { display: true, text: 'Timeframe' }
},
y: {
title: { display: true, text: 'Protein (grams/day)' },
beginAtZero: true
}
},
plugins: {
legend: {
position: 'top',
},
title: {
display: true,
text: 'Estimated Daily Protein Intake Over 12 Weeks'
}
}
}
});
// Update SVG Chart
updateSvgChart(targetProtein, rangeLow, rangeHigh, parseFloat(document.getElementById("bodyWeight").value) || 70); // Pass current body weight
}
function updateSvgChart(target, low, high, bodyWeight) {
var svgNS = "http://www.w3.org/2000/svg";
var chartG = document.getElementById("chartG");
chartG.innerHTML = ''; // Clear previous elements
var svgWidth = 600;
var svgHeight = 300;
var margin = { top: 50, right: 30, bottom: 50, left: 50 };
var chartAreaWidth = svgWidth – margin.left – margin.right;
var chartAreaHeight = svgHeight – margin.top – margin.bottom;
// Determine max protein value for scaling Y-axis
var maxProtein = Math.max(target, low, high);
if (maxProtein === 0) maxProtein = 200; // Default if no data
var yMax = maxProtein * 1.1; // Add some padding
// Scales
var xScale = function(bw) { return margin.left + (bw / (bodyWeight * 1.5)) * chartAreaWidth; }; // Scale based on current weight, extend a bit
var yScale = function(protein) { return margin.top + chartAreaHeight – (protein / yMax) * chartAreaHeight; };
// Data points (e.g., 3 points for demonstration)
var dataPoints = [
{ bw: bodyWeight * 0.8, proteinMin: low * 0.8, proteinMax: high * 0.8, proteinTarget: target * 0.8 },
{ bw: bodyWeight, proteinMin: low, proteinMax: high, proteinTarget: target },
{ bw: bodyWeight * 1.2, proteinMin: low * 1.2, proteinMax: high * 1.2, proteinTarget: target * 1.2 }
];
// Ensure we don't go too far with scaling if bodyWeight is very low/high
var maxConsideredBW = Math.max(bodyWeight * 1.5, 100); // Don't scale beyond ~150% of current BW or 100kg absolute if BW is low
xScale = function(bw) { return margin.left + (bw / maxConsideredBW) * chartAreaWidth; };
// Draw shaded area for protein range
var rangePath = svgNS.create "path";
var pathData = "M" + xScale(dataPoints[0].bw) + "," + yScale(dataPoints[0].proteinMax);
pathData += " L" + xScale(dataPoints[1].bw) + "," + yScale(dataPoints[1].proteinMax);
pathData += " L" + xScale(dataPoints[2].bw) + "," + yScale(dataPoints[2].proteinMax);
pathData += " L" + xScale(dataPoints[2].bw) + "," + yScale(dataPoints[2].proteinMin);
pathData += " L" + xScale(dataPoints[1].bw) + "," + yScale(dataPoints[1].proteinMin);
pathData += " L" + xScale(dataPoints[0].bw) + "," + yScale(dataPoints[0].proteinMin);
pathData += " Z";
rangePath.setAttribute("d", pathData);
rangePath.setAttribute("fill", "rgba(40, 167, 69, 0.2)");
rangePath.setAttribute("stroke", "none");
chartG.appendChild(rangePath);
// Draw line for target protein
var targetPath = svgNS.create "path";
var targetPathData = "M" + xScale(dataPoints[0].bw) + "," + yScale(dataPoints[0].proteinTarget);
targetPathData += " L" + xScale(dataPoints[1].bw) + "," + yScale(dataPoints[1].proteinTarget);
targetPathData += " L" + xScale(dataPoints[2].bw) + "," + yScale(dataPoints[2].proteinTarget);
targetPath.setAttribute("d", targetPathData);
targetPath.setAttribute("fill", "none");
targetPath.setAttribute("stroke", "#004a99");
targetPath.setAttribute("stroke-width", "2");
chartG.appendChild(targetPath);
// Draw points for clarity (optional)
dataPoints.forEach(function(d) {
// Target Point
var targetCircle = svgNS.createElementNS("circle");
targetCircle.setAttribute("cx", xScale(d.bw));
targetCircle.setAttribute("cy", yScale(d.proteinTarget));
targetCircle.setAttribute("r", 4);
targetCircle.setAttribute("fill", "#004a99");
chartG.appendChild(targetCircle);
// Range points (optional, for visualizing the area)
var lowCircle = svgNS.createElementNS("circle");
lowCircle.setAttribute("cx", xScale(d.bw));
lowCircle.setAttribute("cy", yScale(d.proteinMin));
lowCircle.setAttribute("r", 3);
lowCircle.setAttribute("fill", "rgba(40, 167, 69, 0.5)");
chartG.appendChild(lowCircle);
var highCircle = svgNS.createElementNS("circle");
highCircle.setAttribute("cx", xScale(d.bw));
highCircle.setAttribute("cy", yScale(d.proteinMax));
highCircle.setAttribute("r", 3);
highCircle.setAttribute("fill", "rgba(40, 167, 69, 0.5)");
chartG.appendChild(highCircle);
});
// Add X-axis labels
var xLabel1 = svgNS.createElementNS("text");
xLabel1.setAttribute("x", xScale(dataPoints[0].bw));
xLabel1.setAttribute("y", margin.top + chartAreaHeight + 20);
xLabel1.setAttribute("text-anchor", "middle");
xLabel1.setAttribute("font-size", "11");
xLabel1.textContent = Math.round(dataPoints[0].bw) + " kg";
chartG.appendChild(xLabel1);
var xLabel2 = svgNS.createElementNS("text");
xLabel2.setAttribute("x", xScale(dataPoints[1].bw));
xLabel2.setAttribute("y", margin.top + chartAreaHeight + 20);
xLabel2.setAttribute("text-anchor", "middle");
xLabel2.setAttribute("font-size", "11");
xLabel2.textContent = Math.round(dataPoints[1].bw) + " kg";
chartG.appendChild(xLabel2);
var xLabel3 = svgNS.createElementNS("text");
xLabel3.setAttribute("x", xScale(dataPoints[2].bw));
xLabel3.setAttribute("y", margin.top + chartAreaHeight + 20);
xLabel3.setAttribute("text-anchor", "middle");
xLabel3.setAttribute("font-size", "11");
xLabel3.textContent = Math.round(dataPoints[2].bw) + " kg";
chartG.appendChild(xLabel3);
// Add Y-axis labels (simplified – showing key points)
var yLabelMax = svgNS.createElementNS("text");
yLabelMax.setAttribute("x", margin.left – 10);
yLabelMax.setAttribute("y", margin.top + 5);
yLabelMax.setAttribute("text-anchor", "end");
yLabelMax.setAttribute("font-size", "11");
yLabelMax.textContent = Math.round(yMax) + "g";
chartG.appendChild(yLabelMax);
var yLabelMid = svgNS.createElementNS("text");
yLabelMid.setAttribute("x", margin.left – 10);
yLabelMid.setAttribute("y", margin.top + chartAreaHeight / 2);
yLabelMid.setAttribute("text-anchor", "end");
yLabelMid.setAttribute("font-size", "11");
yLabelMid.textContent = Math.round(yMax / 2) + "g";
chartG.appendChild(yLabelMid);
var yLabelZero = svgNS.createElementNS("text");
yLabelZero.setAttribute("x", margin.left – 10);
yLabelZero.setAttribute("y", margin.top + chartAreaHeight);
yLabelZero.setAttribute("text-anchor", "end");
yLabelZero.setAttribute("font-size", "11");
yLabelZero.textContent = "0g";
chartG.appendChild(yLabelZero);
}
// Add event listeners to inputs for real-time updates
document.getElementById("bodyWeight").addEventListener("input", calculateProtein);
document.getElementById("activityLevel").addEventListener("change", calculateProtein);
document.getElementById("goal").addEventListener("change", calculateProtein);
// Initial calculation on page load
window.onload = function() {
// Set default values if fields are empty
if (!document.getElementById("bodyWeight").value) {
document.getElementById("bodyWeight").value = "75"; // Sensible default
}
if (!document.getElementById("activityLevel").value) {
document.getElementById("activityLevel").value = "moderately_active";
}
if (!document.getElementById("goal").value) {
document.getElementById("goal").value = "muscle_gain";
}
calculateProtein(); // Run initial calculation
// Load Chart.js library dynamically if not present
if (typeof Chart === 'undefined') {
var script = document.createElement('script');
script.src = 'https://cdn.jsdelivr.net/npm/chart.js@3.7.0/dist/chart.min.js'; // Use a specific version
script.onload = function() {
updateCharts(); // Update charts once library is loaded
};
document.head.appendChild(script);
} else {
updateCharts(); // Update charts if library is already loaded
}
};