Determine your cat's optimal daily calorie intake for a healthy weight loss journey.
Calculate Your Cat's Daily Calories
Enter your cat's current weight in kilograms.
Enter your cat's ideal healthy weight in kilograms.
Enter your cat's age in years.
Sedentary (Little to no exercise)
Moderately Active (Regular walks/play)
Active (Daily vigorous play/hunting)
Choose the option that best describes your cat's daily activity.
Yes
No
Neutered/spayed cats often require fewer calories.
Your Cat's Weight Loss Calorie Needs
— kcal
Ideal Weight Calories: — kcal/day
Resting Energy Requirement (RER): — kcal/day
Weight Loss Target: — %
Calculated using the formula: Daily Calories = (Ideal Weight Calories) * Activity Factor * Neutered Factor, where Ideal Weight Calories are estimated from standard feline formulas.
Calorie Intake vs. Target Over Time
This chart visualizes your cat's estimated daily calorie needs for weight loss compared to maintenance calories at their ideal weight.
Weight Loss Progress Tracking
Week
Starting Weight (kg)
Ending Weight (kg)
Weight Lost (kg)
Daily Calorie Intake (kcal)
This table helps visualize progress. Assumes ~1-2% body weight loss per week is safe.
What is a Cat Calorie Calculator for Weight Loss?
{primary_keyword} is a specialized tool designed to help cat owners calculate the precise daily calorie intake their feline companion needs to achieve a safe and healthy weight loss. Unlike general pet food calculators, this tool focuses specifically on the caloric deficit required for shedding excess pounds while ensuring nutritional needs are still met. It takes into account factors like current weight, target weight, age, activity level, and neutering status to provide a personalized recommendation.
Who should use it? Any cat owner whose veterinarian has advised that their cat needs to lose weight. Overweight and obese cats are at higher risk for serious health issues such as diabetes, arthritis, heart disease, and urinary tract problems. This calculator empowers owners to take actionable steps towards improving their cat's health and longevity.
Common misconceptions about cat weight loss include:
"My cat is just big-boned." – While some cats are naturally larger, obesity is a distinct health condition.
"Free-feeding is fine." – Uncontrolled access to food often leads to overeating and weight gain.
"Just feed less of the same food." – Simply reducing portion sizes without calculating needs can lead to nutritional deficiencies or an unhealthy rate of weight loss.
"Weight loss is slow and doesn't matter much." – Gradual, consistent weight loss is key for feline health; rapid loss can be dangerous.
Cat Calorie Calculator for Weight Loss Formula and Mathematical Explanation
The core of a {primary_keyword} relies on calculating the cat's energy requirements. A common approach involves determining the Resting Energy Requirement (RER) and then adjusting it based on life stage, activity, and weight management goals. For weight loss, we aim for a controlled deficit.
The process typically involves these steps:
Calculate Resting Energy Requirement (RER): This is the energy needed for basic bodily functions at rest. A widely accepted formula for dogs and cats is:
RER (kcal/day) = 70 * (Body Weight in kg)0.75
Determine Ideal Weight Calories (Calorie Needs for Target Weight): Instead of using current weight, we often use the target or ideal weight to calculate maintenance calories. This is usually RER multiplied by a specific factor (e.g., 1.0 for ideal weight).
Ideal Weight Calories (kcal/day) = RER for Target Weight * 1.0 (assuming ideal weight maintenance)
Apply Weight Loss Factor: To achieve weight loss, a calorie deficit is introduced. A common veterinary recommendation is to reduce daily intake by 20-30% from the ideal maintenance level. This calculator targets a reduction suitable for gradual loss. The formula used here simplifies this by directly calculating the target intake based on ideal weight and applying a deficit factor (often implied within the RER multiplication or a direct target calculation):
Weight Loss Daily Calories = Ideal Weight Calories * Neutered Factor * Activity Level Factor * Weight Loss Deficit Factor
(Note: The calculator simplifies this by directly using adjusted RER multipliers and activity factors that aim for a deficit, implicitly including a deficit factor). A simplified version often used is:
Daily Calories = (Target Weight RER * 1.0) * Activity Level Factor * Neutered Factor (This assumes the RER calculation and target intake implicitly create a deficit appropriate for weight loss, often around 70-80% of maintenance).
Variables Used in Calculation
Variable
Meaning
Unit
Typical Range / Notes
Current Weight
The cat's present weight.
kg
0.5 – 15.0+ kg
Target Weight
The cat's ideal, healthy weight.
kg
0.5 – 10.0 kg (breed dependent)
Age
The cat's age in years.
Years
0.1 – 20+ years
Activity Level Factor
Multiplier based on daily physical activity.
Unitless
1.0 (Sedentary) to 1.4 (Active)
Neutered Factor
Multiplier adjusting for metabolic changes post-neutering.
Unitless
0.8 (Neutered) or 1.0 (Intact)
RER
Resting Energy Requirement.
kcal/day
Calculated value, typically 200-400 kcal for adult cats.
Ideal Weight Calories
Estimated maintenance calories for the target weight.
kcal/day
Calculated value.
Daily Calories (Weight Loss)
Calculated target calorie intake for weight loss.
kcal/day
Typically 70-80% of Ideal Weight Calories.
Practical Examples (Real-World Use Cases)
Example 1: Overweight Adult Cat
Scenario: Whiskers is a 5-year-old male cat who weighs 6.5 kg. His ideal weight, as determined by his vet, is 4.5 kg. He is neutered and moderately active, enjoying daily play sessions.
Weight Loss Target: A common goal is ~10-15% reduction from maintenance. Let's aim for 20% reduction from the RER-based calculation to be safe, using the calculator's integrated factors.
Calculated Daily Calories for Weight Loss: Using the calculator's logic (which integrates factors), the result might be around 180-190 kcal/day. Let's assume the calculator yields: 185 kcal/day.
Interpretation: Whiskers should consume approximately 185 kcal per day to safely lose weight. This represents a deficit from his maintenance needs, encouraging his body to use stored fat for energy. This intake should be divided into at least two meals.
Example 2: Senior Cat Needing Gentle Weight Management
Scenario: Mittens is a 10-year-old female cat weighing 5.2 kg. Her ideal weight is 4.8 kg. She is spayed and has become more sedentary due to her age.
Weight Loss Target: A smaller deficit is appropriate for seniors.
Calculated Daily Calories for Weight Loss: The calculator might suggest approximately 200-210 kcal/day. Let's assume: 205 kcal/day.
Interpretation: Mittens requires about 205 kcal daily. This provides enough energy for her basic needs while allowing for a slow, steady weight loss, which is crucial for senior cats to avoid muscle loss and other complications.
How to Use This Cat Calorie Calculator for Weight Loss
Using our {primary_keyword} is straightforward:
Gather Information: You'll need your cat's current weight (in kg), their ideal target weight (in kg, consult your vet if unsure), age (in years), and an honest assessment of their activity level (Sedentary, Moderately Active, Active). Also, note if they are neutered/spayed.
Input Data: Enter these values into the corresponding fields in the calculator. Ensure you use the correct units (kilograms for weight).
Select Options: Choose the appropriate option for Activity Level and Neutered/Spayed status from the dropdown menus.
Calculate: Click the "Calculate Calories" button.
How to Read Results:
Primary Result (Main Highlighted Number): This is your cat's recommended daily calorie intake (in kcal) for weight loss.
Ideal Weight Calories: The estimated number of calories your cat needs daily to *maintain* their target healthy weight. Your weight loss target is less than this.
Resting Energy Requirement (RER): The baseline calories needed for essential bodily functions.
Weight Loss Target (%): Indicates the approximate percentage reduction from maintenance calories to achieve weight loss.
Decision-Making Guidance:
Consult Your Vet: Always discuss your cat's weight loss plan and the calculated calorie intake with your veterinarian. They can confirm the target weight and ensure no underlying health issues are contributing to obesity.
Portion Control: Use the calculated daily calorie amount to measure your cat's food portions accurately. Use a kitchen scale for precision.
Monitor Progress: Weigh your cat regularly (e.g., weekly or bi-weekly) and adjust calorie intake slightly if weight loss is too rapid or too slow. Aim for a safe loss of 1-2% of body weight per week.
Food Type: Consider using a veterinary-recommended weight management diet, which is formulated to be lower in calories and fat while maintaining essential nutrients.
Enrichment: Incorporate puzzle feeders and interactive play to keep your cat engaged and burn extra calories, making the weight loss journey more successful. This helps to manage feline obesity.
Key Factors That Affect Cat Calorie Calculator Results
While the {primary_keyword} provides a calculated estimate, several factors can influence its accuracy and the overall success of a cat's weight loss plan:
Metabolic Rate Variations: Just like humans, cats have individual metabolic rates. Some naturally burn calories faster or slower, meaning the calculated value is a guideline, not an absolute rule. Age and genetics play a role here.
Body Composition: The calculator assumes a standard distribution of fat and lean mass. A very muscular cat or one with significant muscle loss due to illness might require different caloric adjustments. The RER formula is an estimate.
Underlying Health Conditions: Conditions like hypothyroidism (rare in cats), Cushing's disease, or even arthritis can affect metabolism and energy needs. Certain medications can also impact weight. Consulting a veterinarian is crucial to rule these out.
Type of Food and Calorie Density: Different cat foods have vastly different calorie densities (kcal per cup or can). A weight-loss specific kibble might be lower in calories than a regular canned food, requiring careful measurement to meet the target intake. Ensure the food chosen is nutritionally complete and balanced for weight loss.
Environmental Factors: Temperature can subtly affect metabolic rate. Indoor cats may have different energy expenditures compared to outdoor cats (though outdoor access presents other risks). Stress levels can also influence eating habits and metabolism.
Digestive Health and Nutrient Absorption: Issues like inflammatory bowel disease (IBD) or pancreatic insufficiency can affect how well a cat absorbs nutrients and calories from their food, potentially impacting weight management strategies.
Rate of Weight Loss Goal: Aiming for too rapid a weight loss can be dangerous (risk of hepatic lipidosis). The calculator's output assumes a safe, gradual deficit. If a vet recommends a faster rate (e.g., for critical health reasons), calorie intake might need careful veterinary guidance.
Accurate Measurement: Inconsistent or inaccurate food measurement is a major reason why weight loss plans fail. Using measuring cups can be imprecise; a kitchen scale is highly recommended for accurately portioning food based on the calculated calories. Understanding food labels is key.
Frequently Asked Questions (FAQ)
Q1: How quickly should my cat lose weight?
A: A safe and healthy rate of weight loss for cats is generally 1-2% of their body weight per week. Faster loss can lead to serious health risks like hepatic lipidosis (fatty liver disease).
Q2: What if my cat doesn't like the weight loss food?
A: Try different veterinary-approved weight management diets. Sometimes, transitioning slowly over 7-10 days can help. Warming the food slightly or adding a small amount of low-sodium tuna water (check with your vet) can also increase palatability. If palatability remains an issue, discuss alternatives with your vet.
Q3: Can I just feed my cat less of their regular food?
A: While reducing portion size helps, simply feeding less of a standard diet might not provide all the necessary nutrients in the reduced volume. Veterinary weight management diets are specifically formulated to be nutrient-dense and lower in calories, making them ideal for safe weight loss.
Q4: My cat eats dry food. How do I measure calories accurately?
A: Use a digital kitchen scale to weigh the dry food. Calculate the calorie density of the food (kcal per gram) from the packaging, then weigh out the amount needed to reach the target daily calorie intake calculated by the tool.
Q5: What about treats? Do they count towards the daily calorie total?
A: Absolutely! Treats should ideally constitute no more than 10% of your cat's total daily calorie intake. Opt for low-calorie, cat-specific treats and factor them into the overall calculation. Many commercial treats are very high in calories.
Q6: My cat is underweight. Is this calculator useful?
A: This calculator is specifically for weight *loss*. If your cat is underweight, you should consult a veterinarian to determine the cause and the appropriate plan for healthy weight gain, which involves different nutritional strategies.
Q7: How does age affect calorie needs for weight loss?
A: Senior cats often have lower metabolisms and may require fewer calories for maintenance. Their weight loss should also be slower and more carefully monitored to prevent muscle loss. Kittens and young adults have higher energy needs due to growth and development.
Q8: What is Hepatic Lipidosis and why is rapid weight loss dangerous?
A: Hepatic Lipidosis (Fatty Liver Disease) is a serious condition where the liver becomes overloaded with fat, impairing its function. It often occurs when a cat, particularly an overweight one, stops eating or loses weight too rapidly. The body mobilizes fat stores too quickly for the liver to process, leading to liver failure. This underscores the importance of gradual, veterinarian-supervised weight loss.
var currentWeightKgInput = document.getElementById("currentWeightKg");
var targetWeightKgInput = document.getElementById("targetWeightKg");
var ageYearsInput = document.getElementById("ageYears");
var activityLevelSelect = document.getElementById("activityLevel");
var neuteredSelect = document.getElementById("neutered");
var resultsSection = document.getElementById("resultsSection");
var mainResultDiv = document.getElementById("mainResult");
var idealWeightCalsSpan = document.getElementById("idealWeightCals");
var rerSpan = document.getElementById("rer");
var weightLossTargetSpan = document.getElementById("weightLossTarget");
var chart = null;
var chartContext = null;
var progressTableBody = document.getElementById("progressTable").getElementsByTagName('tbody')[0];
// Default settings for initial display and reset
var defaultCurrentWeightKg = 5.5;
var defaultTargetWeightKg = 4.5;
var defaultAgeYears = 3;
var defaultActivityLevel = "1.2"; // Moderately Active
var defaultNeutered = "0.8"; // Yes
function validateInput(value, id, min, max, name) {
var errorElement = document.getElementById(id + "Error");
var isValid = true;
errorElement.textContent = "";
errorElement.classList.remove("visible");
if (value === "") {
errorElement.textContent = "This field cannot be empty.";
isValid = false;
} else {
var numValue = parseFloat(value);
if (isNaN(numValue)) {
errorElement.textContent = "Please enter a valid number.";
isValid = false;
} else if (numValue max) {
errorElement.textContent = name + " cannot be more than " + max + ".";
isValid = false;
}
}
return isValid;
}
function calculateRER(weightKg) {
// RER = 70 * (weight in kg)^0.75
return 70 * Math.pow(weightKg, 0.75);
}
function calculateCalories() {
var currentWeightKg = parseFloat(currentWeightKgInput.value);
var targetWeightKg = parseFloat(targetWeightKgInput.value);
var ageYears = parseFloat(ageYearsInput.value);
var activityFactor = parseFloat(activityLevelSelect.value);
var neuteredFactor = parseFloat(neuteredSelect.value);
var isValid = true;
if (!validateInput(currentWeightKgInput.value, "currentWeightKg", 0.1, 15.0, "Current Weight")) isValid = false;
if (!validateInput(targetWeightKgInput.value, "targetWeightKg", 0.1, 10.0, "Target Weight")) isValid = false;
if (!validateInput(ageYearsInput.value, "ageYears", 0.1, 25.0, "Age")) isValid = false;
if (!isValid) {
resultsSection.style.display = "none";
return;
}
if (targetWeightKg >= currentWeightKg) {
var errorElement = document.getElementById("targetWeightKgError");
errorElement.textContent = "Target weight must be less than current weight for weight loss.";
errorElement.classList.add("visible");
resultsSection.style.display = "none";
return;
}
// — Calculations —
var rerForTargetWeight = calculateRER(targetWeightKg);
var idealWeightMaintenanceCals = rerForTargetWeight * 1.0; // Standard multiplier for ideal weight maintenance
// Weight loss calculation: Aim for approx 1-2% body weight loss per week.
// This typically means a deficit of 20-30% from maintenance calories.
// A common approach is to use RER * appropriate factor (e.g., 1.0 for maintenance, lower for loss)
// or a direct percentage reduction.
// We will use a slightly simplified method that integrates factors for a deficit.
// For weight loss, we often aim for ~70-80% of maintenance, adjusted by activity and neuter status.
// Let's use a factor that accounts for a deficit, adjusted by activity and neuter status.
// A general guideline for weight loss is ~40-60 kcal/kg of ideal body weight, or a percentage of maintenance.
// We'll use RER for target weight and apply multipliers.
// A common method: target intake = RER * (activity_factor * neuter_factor * other_factors)
// For weight loss, a simplified approach targets ~50-60% of RER for sedentary cats, up to ~70% for active.
// A more robust method might be: Maintenance = RER * 1.2 (for average adult), Weight Loss = Maintenance * 0.7-0.8
// Let's calculate maintenance calories based on target weight RER and a base multiplier, then apply deficit.
// Base maintenance multiplier can vary, often around 1.0-1.3 based on age/neutering.
// For simplicity and common practice, let's consider maintenance around RER * 1.0-1.2.
// Then, apply a deficit for weight loss.
// A common veterinary approach targets around 40-60 kcal/kg of ideal body weight per day.
// Let's calculate that as another reference point:
var caloriesPerKgIdeal = 50; // Mid-range for weight loss (can be 40-60)
var weightLossTargetCalsPerKg = caloriesPerKgIdeal * targetWeightKg; // Target based on ideal weight
// The calculator formula needs to synthesize these. A common simplified formula for weight loss is:
// Daily Calories = RER_TargetWeight * ActivityFactor * NeuteredFactor * DeficitMultiplier
// Let's use a deficit multiplier that makes sense, typically around 0.7-0.8 if RER*factors were maintenance.
// However, the factors themselves can guide towards a deficit.
// Let's assume RER * Activity * Neutered aims for roughly maintenance, and we apply a deficit.
// Or, more directly, we use the RER for target weight and adjust factors to create a deficit.
// Revised approach based on common vet recommendations:
// 1. Calculate RER for target weight.
// 2. Calculate Maintenance Calories: RER * 1.0 (a simpler estimate)
// 3. Calculate Weight Loss Calories: Maintenance Calories * 0.7 (for a ~30% deficit)
// 4. Adjust for Activity and Neutering status slightly, or rely on the initial deficit.
// Let's recalculate using a common vet guideline: Aim for 40-60 kcal/kg of ideal body weight.
// We will use 50 kcal/kg as a baseline for weight loss.
var targetWeightLossCals = targetWeightKg * 50; // Base calories per kg of ideal weight
// Now, adjust this based on activity and neutering status to fine-tune.
// This is where the calculator's specific logic comes in.
// Let's assume the calculator internally uses RER and applies a weighted deficit.
// A common approach: Use RER for target weight * (Activity factor + Neutered factor adjustment) aiming for deficit.
// Let's stick to a common formula structure for simplicity in JS:
// Target Intake = RER_TargetWeight * (Base Maintenance Factor) * (Weight Loss Factor) * (Activity Factor) * (Neutered Factor)
// A common Base Maintenance Factor is ~1.0-1.2. Let's use 1.0 for simplicity with RER.
// A common Weight Loss Factor is ~0.7-0.8. Let's use 0.7 as a starting point for calculation.
// The calculator combines these implicitly.
// Let's recalculate RER for Target Weight
var rerTarget = calculateRER(targetWeightKg); // e.g., 239 kcal for 4.5kg cat
// A common method for weight loss feeding:
// Target daily calories = (RER for Target Weight) * 1.0 (maintenance factor) * 0.7 (weight loss deficit factor)
// Let's use this as the base, and apply activity/neutered factors to that target if needed, OR
// integrate them into the calculation.
// Let's integrate:
// Daily Target = RER_Target * (Weight Loss Factor + Activity Adjustment + Neutered Adjustment)
// This is complex. A simpler, practical approach:
// 1. Calculate RER for Target Weight.
// 2. Calculate Maintenance Calories: RER_Target * 1.2 (example)
// 3. Calculate Weight Loss Target: Maintenance * 0.75 (example deficit)
// Let's use the calculator's implied formula:
// Calculate RER for target weight.
// Apply activity and neutered factors. This may result in a number higher than ideal for loss.
// Then, explicitly apply a weight loss reduction.
// Or, the factors themselves represent the target intake.
// A simplified approach common in calculators:
// Calculate RER for Target Weight.
// Calculate a target range based on ideal weight (e.g., 45-55 kcal/kg).
// Let's use RER calculation as the base.
// Target calories = RER * (a factor that balances activity, neutering, and deficit)
// Standard RER calculation: 70 * W^0.75
// Typical daily energy requirement (DER) for adult cats:
// Neutered, inactive: RER * 1.0
// Neutered, active: RER * 1.2
// Intact, active: RER * 1.4
// For weight loss, we reduce this DER. A common reduction is 20-30%.
// Let's try this:
// 1. Calculate RER for Target Weight: `rerTarget`
// 2. Calculate Estimated Maintenance: `maintenanceCals = rerTarget * activityFactor * neuteredFactor` (This assumes base is RER for target weight)
// 3. Calculate Weight Loss Target: `weightLossCals = maintenanceCals * 0.7` (approx 30% deficit)
// Let's refine based on the common 40-60 kcal/kg of ideal weight range for weight loss.
// We'll use 50 kcal/kg as the primary driver for weight loss target.
var baseWeightLossCals = targetWeightKg * 50;
// Now, adjust this baseline using the activity and neutered factors,
// but the factors are typically multipliers for maintenance.
// For weight loss, these factors might indicate how aggressive the deficit should be.
// A simpler approach: The calculator uses RER as a base and applies multipliers that *result* in a deficit.
// Let's use the formula structure implied by the elements:
// Primary Goal: Weight Loss Calories
// Intermediate: Ideal Weight Maintenance Calories, RER (for target weight)
// Formula: Daily Calories = (Ideal Weight Maintenance Calories) * Activity Factor * Neutered Factor * Weight Loss Deficit Factor
// Let's assume the provided factors (activity, neutered) are used *after* establishing a baseline maintenance,
// OR that they directly modulate a target deficit calculation.
// Simplest integration:
// RER for target weight: `rerTarget`
// Let's use a simple formula structure that results in a deficit:
// Daily Target Calories = RER_TargetWeight * (activityFactor * neuteredFactor * 0.7) // 0.7 for deficit
// This seems too low.
// Let's use the 40-60 kcal/kg approach combined with RER for context.
// RER for Target Weight calculation: `rerTarget`
// Ideal Weight Maintenance Calories estimate: `idealWeightMaintenanceCals = rerTarget * 1.0` (Simplistic maintenance)
// Weight Loss Target Calories: `weightLossCals = idealWeightMaintenanceCals * 0.75` (Approx 25% deficit)
// Re-evaluating common calculator logic:
// Often, they calculate RER for *current* weight (for overall health status)
// then RER for *target* weight, and use that target RER to derive maintenance and then deficit.
// Or, they use the 40-60 kcal/kg rule.
// Let's use the 40-60 kcal/kg rule, adjusted slightly by factors.
// Target Weight Loss = Target Weight (kg) * (Base kcal/kg for WL)
// Base kcal/kg for WL is typically 40-60. Let's use 50 kcal/kg.
var weightLossTargetCals = targetWeightKg * 50;
// Now, incorporate activity and neutered status. These are usually maintenance multipliers.
// For weight loss, we *reduce* maintenance.
// If we use activity/neutered factors, they should modify the target.
// A common way: Target = (RER_Target * ActivityFactor * NeuteredFactor) * DeficitFactor
// Let's assume the calculator's factors *already incorporate* a deficit implicitly.
// If RER = 239 for 4.5kg cat.
// Activity 1.2, Neutered 0.8.
// Maintenance might be RER * 1.2 = 287.
// Weight loss target might be 287 * 0.7 = 201.
// Let's use this formula structure:
// Weight Loss Calories = (RER for Target Weight) * Activity Factor * Neutered Factor * (Weight Loss Deficit Factor)
// Let's assume the factors provided (1.0, 1.2, 1.4 for activity; 0.8, 1.0 for neutered) are part of the DER calculation,
// and we apply a deficit to that DER. A 25% deficit is common.
// Simplified approach for the calculator:
// RER for target weight: `rerTarget`
// Calculate a target intake that includes a deficit.
// Let's use a formula that works well:
// Target Calorie Intake = (70 * targetWeightKg^0.75) * activityFactor * neuteredFactor * 0.7 <- this might be too aggressive deficit
// Let's refine:
// Target Calorie Intake = (70 * targetWeightKg^0.75) * (activityFactor * neuteredFactor) * 0.8 <- 20% deficit on derived DER
// Test with values: target 4.5kg, activity 1.2, neutered 0.8
// RER_Target = 239
// DER = 239 * 1.2 * 0.8 = 229.44
// Weight Loss Target = 229.44 * 0.8 = 183.55 kcal
var calculatedWeightLossCals = rerTarget * activityFactor * neuteredFactor * 0.8; // Using 0.8 for ~20% deficit
// Ensure a minimum intake is suggested for safety, e.g., RER itself or slightly above.
var minSafeIntake = rerTarget * 1.05; // Ensure slightly above RER
if (calculatedWeightLossCals maxReasonableIntake) {
calculatedWeightLossCals = maxReasonableIntake;
}
// Clamp values to reasonable ranges
calculatedWeightLossCals = Math.max(150, calculatedWeightLossCals); // Minimum sensible intake
// Calculate percentage of current weight to lose
var weightToLose = currentWeightKg – targetWeightKg;
var weightLossPercentage = (weightToLose / currentWeightKg) * 100;
// Update results display
mainResultDiv.textContent = calculatedWeightLossCals.toFixed(0) + " kcal";
idealWeightCalsSpan.textContent = idealWeightMaintenanceCals.toFixed(0); // Show maintenance estimate
rerSpan.textContent = rerTarget.toFixed(0);
weightLossTargetSpan.textContent = weightLossPercentage.toFixed(1) + "%";
resultsSection.style.display = "block";
// Update Chart
updateChart(calculatedWeightLossCals, idealWeightMaintenanceCals);
// Update Table (simulate one row for current state)
updateProgressTable(calculatedWeightLossCals);
return calculatedWeightLossCals; // Return for chart update if needed
}
function updateProgressTable(dailyCals) {
// Clear existing rows except header
while (progressTableBody.rows.length > 0) {
progressTableBody.deleteRow(0);
}
// Add a simulated starting row
var row = progressTableBody.insertRow();
var cell1 = row.insertCell(0);
var cell2 = row.insertCell(1);
var cell3 = row.insertCell(2);
var cell4 = row.insertCell(3);
var cell5 = row.insertCell(4);
cell1.textContent = "Start";
cell2.textContent = parseFloat(currentWeightKgInput.value).toFixed(1);
cell3.textContent = "-"; // Ending weight not yet known
cell4.textContent = "-"; // Weight lost not yet known
cell5.textContent = dailyCals.toFixed(0);
}
function updateChart(weightLossCals, maintenanceCals) {
if (!chartContext) {
var canvas = document.getElementById('calorieChart');
chartContext = canvas.getContext('2d');
}
var labels = ['Current Goal', 'Ideal Maintenance'];
var dataPoints = [parseFloat(weightLossCals.toFixed(0)), parseFloat(maintenanceCals.toFixed(0))];
if (chart) {
chart.destroy(); // Destroy previous chart instance if it exists
}
chart = new Chart(chartContext, {
type: 'bar',
data: {
labels: labels,
datasets: [{
label: 'Daily Calories (kcal)',
data: dataPoints,
backgroundColor: [
'rgba(40, 167, 69, 0.7)', // Success color for weight loss target
'rgba(0, 74, 153, 0.7)' // Primary color for maintenance
],
borderColor: [
'rgba(40, 167, 69, 1)',
'rgba(0, 74, 153, 1)'
],
borderWidth: 1
}]
},
options: {
responsive: true,
maintainAspectRatio: false,
scales: {
y: {
beginAtZero: true,
title: {
display: true,
text: 'Calories (kcal)'
}
}
},
plugins: {
legend: {
position: 'top',
},
title: {
display: true,
text: 'Calorie Targets: Weight Loss vs. Maintenance'
}
}
}
});
}
function resetForm() {
currentWeightKgInput.value = defaultCurrentWeightKg;
targetWeightKgInput.value = defaultTargetWeightKg;
ageYearsInput.value = defaultAgeYears;
activityLevelSelect.value = defaultActivityLevel;
neuteredSelect.value = defaultNeutered;
// Clear errors
var errorElements = document.querySelectorAll('.error-message');
for (var i = 0; i 0) {
progressTableBody.deleteRow(0);
}
}
function copyResults() {
var mainResult = mainResultDiv.textContent;
var idealCals = idealWeightCalsSpan.textContent;
var rer = rerSpan.textContent;
var targetPercent = weightLossTargetSpan.textContent;
var assumptions = "Assumptions:\n" +
"- Activity Level: " + activityLevelSelect.options[activityLevelSelect.selectedIndex].text + "\n" +
"- Neutered/Spayed: " + neuteredSelect.options[neuteredSelect.selectedIndex].text + "\n" +
"- Current Weight: " + currentWeightKgInput.value + " kg\n" +
"- Target Weight: " + targetWeightKgInput.value + " kg\n" +
"- Age: " + ageYearsInput.value + " years";
var textToCopy = "— Cat Weight Loss Calorie Calculation —\n\n" +
"Recommended Daily Intake for Weight Loss: " + mainResult + "\n" +
"Ideal Weight Maintenance Calories: " + idealCals + "\n" +
"Resting Energy Requirement (Target Weight): " + rer + "\n" +
"Weight Loss Target Percentage: " + targetPercent + "\n\n" +
assumptions;
// Use navigator.clipboard for modern browsers, fallback to textarea
if (navigator.clipboard && window.isSecureContext) {
navigator.clipboard.writeText(textToCopy).then(function() {
alert('Results copied to clipboard!');
}).catch(function(err) {
console.error('Could not 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';
alert('Fallback: Copy ' + msg);
} catch (err) {
alert('Fallback: Oops, unable to copy');
}
document.body.removeChild(textArea);
}
// Initial calculation on load if default values are set
// Add event listeners for real-time updates
currentWeightKgInput.addEventListener('input', calculateCalories);
targetWeightKgInput.addEventListener('input', calculateCalories);
ageYearsInput.addEventListener('input', calculateCalories);
activityLevelSelect.addEventListener('change', calculateCalories);
neuteredSelect.addEventListener('change', calculateCalories);
// Set default values and trigger initial calculation
document.addEventListener('DOMContentLoaded', function() {
resetForm(); // This will set defaults and trigger calculateCalories
// Ensure calculation runs after defaults are set
var event = new Event('input', { bubbles: true });
currentWeightKgInput.dispatchEvent(event);
event = new Event('change', { bubbles: true });
activityLevelSelect.dispatchEvent(event);
});