Calculate Ideal Body Weight Considering Age | Health Calculator
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Ideal Body Weight Calculator (Age-Adjusted)
Enter your details to find your ideal weight range.
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Your Ideal Weight Range
–.– kg
Formula Used: This calculator uses a modified version of the Devine formula, adjusted for age. The standard Devine formula calculates a base weight, and age factors are applied to refine this for different life stages, reflecting potential metabolic and body composition changes. For adults, it generally assumes a base range and adjusts slightly based on age.
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Ideal Weight vs. Age
Series: Ideal Weight Lower Limit | Ideal Weight Upper Limit
Age-Based Weight Adjustment Factors
Age Group (Years)
Sex
Factor Applied to Base Weight
What is Ideal Body Weight Considering Age?
Determining your ideal body weight is a crucial step towards understanding your overall health and well-being. While often thought of as a single number, your healthy weight is actually a range. Furthermore, this range isn't static; it can be influenced by various factors, including your age. Understanding your ideal body weight considering age helps you set realistic health goals, monitor potential health risks associated with weight, and personalize your fitness and nutrition strategies. It's a dynamic health metric that acknowledges the physiological changes your body undergoes throughout life.
Who Should Use It?
Anyone interested in their health and weight management should consider their ideal body weight, especially when factoring in age. This includes:
Individuals looking to lose or gain weight for health reasons.
People seeking to understand their risk factors for weight-related diseases.
Those who have noticed changes in their weight or body composition over time and want a personalized benchmark.
Fitness enthusiasts and athletes aiming to optimize their performance.
Healthcare professionals using it as a reference point for patient counseling.
Common Misconceptions
Several myths surround the concept of ideal body weight:
Myth: There's one magic number for everyone. Reality: Healthy weight is a range, and factors like muscle mass, bone density, and age play a significant role.Myth: Age is irrelevant to ideal weight. Reality: Metabolism slows, body composition changes, and hormonal shifts occur with age, influencing healthy weight ranges. Our calculator addresses this by incorporating age adjustments.Myth: Ideal weight is solely about appearance. Reality: While appearance is subjective, ideal body weight is primarily a health indicator, reflecting a balance that minimizes disease risk.Myth: All weight formulas are equal. Reality: Different formulas have varying levels of scientific backing and applicability. Some are more general, while others, like the age-adjusted approach, offer greater personalization.
Ideal Body Weight Considering Age Formula and Mathematical Explanation
Calculating ideal body weight considering age involves using established formulas and then applying age-specific adjustments. One widely recognized method is the Devine formula, which provides a baseline. We then refine this by considering how body composition and metabolic rate typically change with age. This approach aims for a more nuanced and accurate representation of a healthy weight range across different life stages.
The Devine Formula (Baseline)
The original Devine formulas, developed in the 1970s, are still a common starting point:
For Men: 50 kg + 2.3 kg for each inch over 5 feetFor Women: 45.5 kg + 2.3 kg for each inch over 5 feet
To use this practically, we first convert height in centimeters to feet and inches.
Age Adjustment Factors
Metabolic rate generally slows down as individuals age, and body composition can shift (e.g., decrease in muscle mass, increase in body fat percentage). While precise universal age-adjustment factors are complex and debated, a common approach in practical calculators is to:
Maintain the standard range for young to middle-aged adults.
Slightly increase the upper end of the ideal weight range for older adults (e.g., 60+) to account for increased bone density and potentially higher essential body fat needed for maintaining health and preventing frailty.
Some approaches might slightly decrease the range for very young adults to reflect ongoing development, though this calculator focuses on adult ranges.
For simplicity and clinical relevance, this calculator applies a moderate adjustment, typically increasing the upper limit by a small percentage for individuals 60 and older, recognizing that a slightly higher weight might be healthier for them compared to the standard range.
Our Calculator's Approach
Our calculator takes your height (in cm), age, and sex to compute an ideal body weight considering age range. It first calculates a base ideal weight using the Devine formula (adapted for metric units) and then applies an age-based adjustment factor. The output is presented as a range (lower and upper limits) and the corresponding Body Mass Index (BMI) range, which provides further context.
Variables Table
Variable
Meaning
Unit
Typical Range / Input
Height (H)
Individual's height
Centimeters (cm)
140 – 210 cm
Age (A)
Individual's age
Years
18 – 99+ Years
Sex
Biological sex
Categorical (Male/Female)
Male, Female
Base Ideal Weight (BIW)
Weight calculated using Devine formula
Kilograms (kg)
Varies based on Height & Sex
Age Factor (AF)
Adjustment multiplier based on age
Decimal (e.g., 1.00, 1.05)
Typically 1.00 (for adults = 60)
Ideal Weight Lower Limit (IWLL)
Lower end of the healthy weight range
Kilograms (kg)
BIW * 0.9 * AF
Ideal Weight Upper Limit (IWUL)
Upper end of the healthy weight range
Kilograms (kg)
BIW * 1.1 * AF
Corresponding BMI Range
BMI values for IWLL and IWUL
kg/m²
18.5 – 24.9 (Standard Healthy Range)
Practical Examples (Real-World Use Cases)
Example 1: A Middle-Aged Woman
Scenario: Sarah is a 45-year-old woman, 165 cm tall, and wants to understand her target weight range.
Inputs:
Height: 165 cm
Age: 45 years
Sex: Female
Calculation Steps (Simplified):
Convert height to inches: 165 cm ≈ 64.96 inches.
Calculate base ideal weight (Devine for Female): 45.5 kg + 2.3 kg/inch * (64.96 – 60) inches ≈ 45.5 + 2.3 * 4.96 ≈ 45.5 + 11.41 = 56.91 kg.
Apply age factor: Since Sarah is 45, the age factor is typically 1.00.
Calculate range:
Lower Limit: 56.91 kg * 0.9 * 1.00 ≈ 51.2 kg
Upper Limit: 56.91 kg * 1.1 * 1.00 ≈ 62.6 kg
Calculate BMI:
Height in meters: 1.65 m. Height squared: 2.7225 m².
BMI for 51.2 kg: 51.2 / 2.7225 ≈ 18.8
BMI for 62.6 kg: 62.6 / 2.7225 ≈ 23.0
Results Interpretation: Sarah's ideal body weight range, considering her age and sex, is approximately 51.2 kg to 62.6 kg. This corresponds to a BMI range of 18.8 to 23.0, which falls within the standard healthy BMI category. She can use this information to guide her nutrition and exercise goals.
Example 2: An Older Gentleman
Scenario: Mr. Chen is 72 years old, stands 175 cm tall, and wants to know his healthy weight range.
Inputs:
Height: 175 cm
Age: 72 years
Sex: Male
Calculation Steps (Simplified):
Convert height to inches: 175 cm ≈ 68.9 inches.
Calculate base ideal weight (Devine for Male): 50 kg + 2.3 kg/inch * (68.9 – 60) inches ≈ 50 + 2.3 * 8.9 ≈ 50 + 20.47 = 70.47 kg.
Apply age factor: Since Mr. Chen is 72 (>= 60), an age factor of approximately 1.05 is applied.
Calculate range:
Lower Limit: 70.47 kg * 0.9 * 1.05 ≈ 66.7 kg
Upper Limit: 70.47 kg * 1.1 * 1.05 ≈ 81.1 kg
Calculate BMI:
Height in meters: 1.75 m. Height squared: 3.0625 m².
BMI for 66.7 kg: 66.7 / 3.0625 ≈ 21.8
BMI for 81.1 kg: 81.1 / 3.0625 ≈ 26.5
Results Interpretation: For Mr. Chen, the age-adjusted ideal body weight range is approximately 66.7 kg to 81.1 kg. The corresponding BMI range is 21.8 to 26.5. Notice the upper limit is higher and the BMI range extends slightly into the overweight category (25-29.9) compared to younger adults. This reflects the understanding that for older adults, maintaining a slightly higher weight can sometimes be beneficial for bone health, muscle mass, and overall resilience. It's crucial to consult a doctor to interpret these results in the context of his specific health status.
How to Use This Ideal Body Weight Calculator
Using our ideal body weight considering age calculator is straightforward. Follow these steps for a personalized assessment:
Step-by-Step Instructions
Enter Height: Input your height accurately in centimeters (cm).Enter Age: Provide your current age in years.Select Sex: Choose 'Male' or 'Female' based on your biological sex.Click Calculate: Press the "Calculate" button.View Results: The calculator will display your ideal weight range in kilograms (kg), the lower and upper limits, and the corresponding healthy BMI range.Understand the Formula: Read the brief explanation below the results to understand the basis of the calculation (Devine formula with age adjustment).Explore Data: Check the generated chart and table for visual insights into how age affects weight considerations.Copy Results: Use the "Copy Results" button to easily save your calculated range and key figures.Reset: If you need to start over or make changes, click the "Reset" button to revert to default or initial input values.
How to Read Results
Ideal Weight Result (Range): This is your primary output, showing the healthy weight range (e.g., 55.0 kg – 65.0 kg). Aiming to stay within this range is beneficial for long-term health.Lower Limit & Upper Limit: These are the boundaries of your healthy weight range.BMI Range: This shows the Body Mass Index associated with your ideal weight range. A BMI between 18.5 and 24.9 is generally considered healthy for most adults. Note that for older adults, a slightly higher BMI might be acceptable or even beneficial.Chart & Table: The chart visually represents how the ideal weight range might shift slightly with age, while the table details the adjustment factors used.
Decision-Making Guidance
Use these results as a guide, not a rigid rule. They provide a scientifically-backed starting point for your health journey. If your current weight falls outside this range, consult with a healthcare professional or a registered dietitian. They can help you create a safe and effective plan tailored to your individual needs, considering factors beyond just weight, such as body composition, medical history, and lifestyle.
Key Factors That Affect Ideal Body Weight Results
While our calculator provides a personalized estimate, several real-world factors can influence your *actual* healthy weight and body composition. Understanding these helps in interpreting the results more holistically:
Body Composition (Muscle vs. Fat): Muscle is denser than fat. An individual with a high muscle mass might weigh more than someone of the same height and age but with less muscle, yet both could be considered healthy. The standard formulas don't directly measure body fat percentage.Bone Density: People with naturally larger or denser bone structures may weigh more. Formulas typically don't account for skeletal frame size.Genetics: Your genetic makeup plays a significant role in determining your body type, metabolism, and where you tend to store fat. Some individuals are predisposed to being naturally leaner or heavier.Activity Level: A highly active person, especially one involved in endurance or strength training, will have different body composition needs and potentially a different healthy weight than a sedentary individual. Athletes often fall outside standard 'ideal' ranges due to muscle mass.Hormonal Changes: Fluctuations or changes in hormones (e.g., during menopause, due to thyroid issues) can significantly impact weight, metabolism, and body fat distribution, which standard formulas might not fully capture.Medical Conditions & Medications: Certain health conditions (like PCOS, diabetes) and medications can affect weight regulation, fluid balance, and metabolism, influencing what is a healthy weight for an individual.Dietary Habits: While not directly in the calculation, long-term dietary patterns influence body composition and overall health, which are the underlying goals of determining an ideal weight.Hydration Levels: Temporary fluctuations in body weight can occur due to hydration status, though this doesn't affect the long-term *ideal* weight calculation.
Frequently Asked Questions (FAQ)
What is the difference between ideal body weight and a healthy weight range?
Ideal body weight often refers to a specific number predicted by formulas, while a healthy weight range acknowledges that there is variability and a spectrum of weights that are associated with good health outcomes. Our calculator provides a range to reflect this.
Why does age matter in ideal body weight calculations?
As we age, our metabolism tends to slow down, body composition changes (muscle mass may decrease, fat mass may increase), and hormonal profiles shift. These physiological changes can affect what is considered a healthy weight range for optimal health and longevity.
Is the Devine formula the only way to calculate ideal body weight?
No, there are other formulas like the Hamwi, Robinson, and Miller formulas. Each has its own basis and might yield slightly different results. The Devine formula is commonly used due to its relative simplicity and widespread adoption.
Can this calculator be used for children or adolescents?
This specific calculator is designed for adults. Ideal body weight calculations for children and adolescents are more complex, as they need to account for growth and development, and are typically assessed using growth charts and BMI-for-age percentiles.
My current weight is outside the calculated range. What should I do?
It's common for current weights to differ from calculated ideal ranges. This calculator provides a guideline. Consult with a healthcare professional (doctor, registered dietitian) to discuss your specific situation, health status, and develop a personalized plan if weight management is a goal.
How accurate are these age-adjusted formulas?
These formulas are estimations and should be used as a guide. They don't account for individual variations in body composition, genetics, or specific health conditions. A holistic approach combining weight metrics with lifestyle factors and professional medical advice is best.
Does body fat percentage matter more than ideal body weight?
Both are important. While ideal body weight gives a general indication, body fat percentage provides a more direct measure of body composition and health risk. High body fat, even within an 'ideal' weight range, can still pose health risks. Conversely, someone slightly above their 'ideal' weight but with a healthy body fat percentage might be perfectly healthy.
Can I use this calculator if I'm pregnant or breastfeeding?
No, this calculator is not suitable for pregnant or breastfeeding individuals. Weight management during these periods requires specific medical guidance due to the unique physiological needs involved.
Related Tools and Internal Resources
© 2023 Your Health Resource. All rights reserved.
Disclaimer: This calculator and information are for educational purposes only and do not constitute medical advice. Always consult with a qualified healthcare provider for any health concerns or before making any decisions related to your health or treatment.
// Calculator Logic
function calculateIdealBodyWeight() {
var heightCm = parseFloat(document.getElementById("heightCm").value);
var age = parseInt(document.getElementById("age").value);
var sex = document.getElementById("sex").value;
var heightCmError = document.getElementById("heightCmError");
var ageError = document.getElementById("ageError");
var sexError = document.getElementById("sexError"); // Though select, good practice
// Clear previous errors
heightCmError.textContent = "";
ageError.textContent = "";
sexError.textContent = "";
var isValid = true;
// Input Validation
if (isNaN(heightCm) || heightCm <= 0) {
heightCmError.textContent = "Please enter a valid height in centimeters.";
isValid = false;
} else if (heightCm 250) {
heightCmError.textContent = "Height must be between 100 cm and 250 cm.";
isValid = false;
}
if (isNaN(age) || age <= 0) {
ageError.textContent = "Please enter a valid age.";
isValid = false;
} else if (age 120) {
ageError.textContent = "Age must be between 18 and 120 years.";
isValid = false;
}
// Sex validation is less critical for select, but good to have a check if needed
if (!sex) {
sexError.textContent = "Please select a sex.";
isValid = false;
}
if (!isValid) {
resetResults(); // Clear results if validation fails
return;
}
// Calculations
var heightInches = heightCm / 2.54;
var baseIdealWeightKg;
if (sex === "male") {
baseIdealWeightKg = 50 + (heightInches – 60) * 2.3;
} else { // female
baseIdealWeightKg = 45.5 + (heightInches – 60) * 2.3;
}
var ageFactor = 1.00;
if (age >= 60) {
ageFactor = 1.05; // Slight increase for older adults
}
var weightLowerLimitKg = baseIdealWeightKg * 0.9 * ageFactor;
var weightUpperLimitKg = baseIdealWeightKg * 1.1 * ageFactor;
// Ensure limits are not negative (highly unlikely but safe)
weightLowerLimitKg = Math.max(0, weightLowerLimitKg);
weightUpperLimitKg = Math.max(0, weightUpperLimitKg);
// Calculate BMI Range
var heightMeters = heightCm / 100;
var heightMetersSq = heightMeters * heightMeters;
var bmiLower = (weightLowerLimitKg / heightMetersSq).toFixed(1);
var bmiUpper = (weightUpperLimitKg / heightMetersSq).toFixed(1);
// Display Results
document.getElementById("idealWeightResult").textContent = weightLowerLimitKg.toFixed(1) + " – " + weightUpperLimitKg.toFixed(1) + " kg";
document.getElementById("weightRangeLow").textContent = "Lower Limit: " + weightLowerLimitKg.toFixed(1) + " kg";
document.getElementById("weightRangeHigh").textContent = "Upper Limit: " + weightUpperLimitKg.toFixed(1) + " kg";
document.getElementById("bmiRange").textContent = "BMI Range: " + bmiLower + " – " + bmiUpper + " kg/m²";
// Update Chart Data
updateChart(weightLowerLimitKg, weightUpperLimitKg, age);
// Update Table Data
updateTable(sex);
// Show sections
document.getElementById("chartSection").style.display = "block";
document.getElementById("tableSection").style.display = "block";
document.getElementById("resultsDiv").style.display = "block"; // Ensure results div is visible
}
function resetResults() {
document.getElementById("idealWeightResult").textContent = "–.– kg";
document.getElementById("weightRangeLow").textContent = "Lower Limit: –.– kg";
document.getElementById("weightRangeHigh").textContent = "Upper Limit: –.– kg";
document.getElementById("bmiRange").textContent = "BMI Range: –.– – –.–";
document.getElementById("heightCm").value = "";
document.getElementById("age").value = "";
document.getElementById("sex").value = "male"; // Reset to default
document.getElementById("heightCmError").textContent = "";
document.getElementById("ageError").textContent = "";
document.getElementById("sexError").textContent = "";
// Clear canvas
var canvas = document.getElementById('weightChart');
if (canvas) {
var ctx = canvas.getContext('2d');
ctx.clearRect(0, 0, canvas.width, canvas.height);
}
document.getElementById("chartSection").style.display = "none";
document.getElementById("tableSection").style.display = "none";
}
function resetCalculatorInputs() {
document.getElementById("heightCm").value = "";
document.getElementById("age").value = "";
document.getElementById("sex").value = "male";
document.getElementById("heightCmError").textContent = "";
document.getElementById("ageError").textContent = "";
document.getElementById("sexError").textContent = "";
resetResults(); // Also clears results display and hides chart/table
}
function copyResults() {
var idealWeightResult = document.getElementById("idealWeightResult").textContent;
var weightRangeLow = document.getElementById("weightRangeLow").textContent;
var weightRangeHigh = document.getElementById("weightRangeHigh").textContent;
var bmiRange = document.getElementById("bmiRange").textContent;
var height = document.getElementById("heightCm").value;
var age = document.getElementById("age").value;
var sex = document.getElementById("sex").value;
var assumptions = "Assumptions:\n";
assumptions += "- Height: " + (height ? height + " cm" : "–") + "\n";
assumptions += "- Age: " + (age ? age + " years" : "–") + "\n";
assumptions += "- Sex: " + (sex ? sex.charAt(0).toUpperCase() + sex.slice(1) : "–") + "\n";
assumptions += "- Formula: Devine formula adjusted for age.\n";
var textToCopy = "Ideal Body Weight Results:\n"
+ idealWeightResult + "\n\n"
+ weightRangeLow + "\n"
+ weightRangeHigh + "\n"
+ bmiRange + "\n\n"
+ assumptions;
navigator.clipboard.writeText(textToCopy).then(function() {
var feedback = document.querySelector(".copy-feedback");
feedback.style.display = "block";
setTimeout(function() {
feedback.style.display = "none";
}, 3000);
}).catch(function(err) {
console.error("Failed to copy text: ", err);
// Optionally display an error message to the user
});
}
// Charting Logic using Canvas
var chartInstance = null; // To hold chart object
function updateChart(lowerLimit, upperLimit, age) {
var canvas = document.getElementById('weightChart');
if (!canvas) return;
var ctx = canvas.getContext('2d');
// Destroy previous chart instance if it exists
if (chartInstance) {
chartInstance.destroy();
}
// Define age groups for chart x-axis
var ageGroups = [18, 25, 35, 45, 55, 65, 75, 85, 95];
var dataLower = [];
var dataUpper = [];
// Generate data points for the chart based on age groups
for (var i = 0; i = 60) {
ageFactorChart = 1.05;
}
// Re-calculate a base weight for each age group using a standard height (e.g. 170cm for female, 175cm for male)
// This is a simplification for visualization. A more complex chart might use the user's height.
// For this example, let's assume a reference height for visualization purposes:
var refHeightCm = (document.getElementById("sex").value === "male") ? 175 : 165; // Reference height
var refHeightInches = refHeightCm / 2.54;
var refBaseWeightKg;
if (document.getElementById("sex").value === "male") {
refBaseWeightKg = 50 + (refHeightInches – 60) * 2.3;
} else {
refBaseWeightKg = 45.5 + (refHeightInches – 60) * 2.3;
}
dataLower.push((refBaseWeightKg * 0.9 * ageFactorChart).toFixed(1));
dataUpper.push((refBaseWeightKg * 1.1 * ageFactorChart).toFixed(1));
}
chartInstance = new Chart(ctx, {
type: 'line',
data: {
labels: ageGroups.map(function(age) { return age + " yrs"; }),
datasets: [{
label: 'Ideal Weight Lower Limit (kg)',
data: dataLower,
borderColor: 'var(–primary-color)',
backgroundColor: 'rgba(0, 74, 153, 0.1)',
fill: false,
tension: 0.1,
pointRadius: 5,
pointBackgroundColor: 'var(–primary-color)'
}, {
label: 'Ideal Weight Upper Limit (kg)',
data: dataUpper,
borderColor: 'var(–success-color)',
backgroundColor: 'rgba(40, 167, 69, 0.1)',
fill: false,
tension: 0.1,
pointRadius: 5,
pointBackgroundColor: 'var(–success-color)'
}]
},
options: {
responsive: true,
maintainAspectRatio: false,
scales: {
x: {
title: {
display: true,
text: 'Age (Years)'
}
},
y: {
title: {
display: true,
text: 'Weight (kg)'
},
beginAtZero: true
}
},
plugins: {
tooltip: {
callbacks: {
label: function(context) {
var label = context.dataset.label || ";
if (label) {
label += ': ';
}
if (context.parsed.y !== null) {
label += context.parsed.y + ' kg';
}
return label;
}
}
}
}
}
});
}
// Table Logic
function updateTable(sex) {
var tableBody = document.getElementById("adjustmentTableBody");
tableBody.innerHTML = ""; // Clear previous content
var ageGroups = [
{ label: "18-39", min: 18, max: 39, factor: 1.00 },
{ label: "40-59", min: 40, max: 59, factor: 1.00 },
{ label: "60+", min: 60, max: 120, factor: 1.05 }
];
for (var i = 0; i < ageGroups.length; i++) {
var row = tableBody.insertRow();
var cell1 = row.insertCell(0);
var cell2 = row.insertCell(1);
var cell3 = row.insertCell(2);
cell1.textContent = ageGroups[i].label;
cell2.textContent = sex.charAt(0).toUpperCase() + sex.slice(1);
cell3.textContent = ageGroups[i].factor.toFixed(2);
}
}
// FAQ Toggle Function
function toggleFaq(element) {
var paragraph = element.nextElementSibling;
var faqItem = element.parentElement;
if (paragraph.style.display === "block") {
paragraph.style.display = "none";
faqItem.classList.remove("open");
} else {
paragraph.style.display = "block";
faqItem.classList.add("open");
}
}
// Event Listeners
document.getElementById("calculateBtn").addEventListener("click", calculateIdealBodyWeight);
document.getElementById("resetBtn").addEventListener("click", resetCalculatorInputs);
document.getElementById("copyBtn").addEventListener("click", copyResults);
// Add event listeners to inputs for real-time updates (optional, but good UX)
document.getElementById("heightCm").addEventListener("input", calculateIdealBodyWeight);
document.getElementById("age").addEventListener("input", calculateIdealBodyWeight);
document.getElementById("sex").addEventListener("change", calculateIdealBodyWeight);
// Initialize the chart with placeholder data or hide initially
document.addEventListener("DOMContentLoaded", function() {
resetResults(); // Ensure results are cleared on initial load
// Initial chart setup (optional, could be empty or default values)
updateChart(0, 0, 18); // Placeholder update, will be replaced on first calculation
});
// Inject CSS variable values into JS for Chart.js to use
function setChartColors() {
var rootStyles = getComputedStyle(document.documentElement);
var primaryColor = rootStyles.getPropertyValue('–primary-color').trim();
var successColor = rootStyles.getPropertyValue('–success-color').trim();
// This part assumes Chart.js is loaded and available
if (typeof Chart !== 'undefined' && chartInstance) {
chartInstance.data.datasets[0].borderColor = primaryColor;
chartInstance.data.datasets[0].pointBackgroundColor = primaryColor;
chartInstance.data.datasets[1].borderColor = successColor;
chartInstance.data.datasets[1].pointBackgroundColor = successColor;
chartInstance.update();
} else if (typeof Chart !== 'undefined') {
// If chartInstance doesn't exist yet, prepare for when it's created
// This could involve passing colors to updateChart or setting them globally
}
}
// Call setChartColors after chartInstance is potentially created or updated
// For now, hardcoded colors are used within updateChart, but this shows how to dynamically get them.