Lose Weight Calculator

Weight Loss Goal Calculator

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 a week) Extra Active (very hard exercise/physical job)

(Healthy range is typically 1-2 lbs per week)

function calculateWeightLoss() { var currentWeight = parseFloat(document.getElementById('currentWeight').value); var targetWeight = parseFloat(document.getElementById('targetWeight').value); var heightFeet = parseFloat(document.getElementById('heightFeet').value); var heightInches = parseFloat(document.getElementById('heightInches').value); var age = parseFloat(document.getElementById('age').value); var gender = document.querySelector('input[name="gender"]:checked').value; var activityLevel = document.getElementById('activityLevel').value; var desiredWeeklyLoss = parseFloat(document.getElementById('desiredWeeklyLoss').value); var resultDiv = document.getElementById('result'); // Input validation if (isNaN(currentWeight) || isNaN(targetWeight) || isNaN(heightFeet) || isNaN(heightInches) || isNaN(age) || isNaN(desiredWeeklyLoss) || currentWeight <= 0 || targetWeight <= 0 || heightFeet <= 0 || age <= 0 || desiredWeeklyLoss = currentWeight) { resultDiv.innerHTML = 'Your target weight must be less than your current weight to lose weight.'; return; } if (desiredWeeklyLoss > 2.5) { resultDiv.innerHTML = 'Warning: Losing more than 2.5 lbs per week is generally not recommended without medical supervision. Please consult a healthcare professional.'; // Continue calculation but with a warning } // Convert height to cm and weight to kg for BMR calculation var totalHeightCm = ((heightFeet * 12) + heightInches) * 2.54; var currentWeightKg = currentWeight * 0.453592; // Calculate Basal Metabolic Rate (BMR) using Mifflin-St Jeor Equation var bmr; if (gender === 'male') { bmr = (10 * currentWeightKg) + (6.25 * totalHeightCm) – (5 * age) + 5; } else { // female bmr = (10 * currentWeightKg) + (6.25 * totalHeightCm) – (5 * age) – 161; } // Apply activity multiplier to get Total Daily Energy Expenditure (TDEE) var activityMultiplier; switch (activityLevel) { case 'sedentary': activityMultiplier = 1.2; break; case 'lightlyActive': activityMultiplier = 1.375; break; case 'moderatelyActive': activityMultiplier = 1.55; break; case 'veryActive': activityMultiplier = 1.725; break; case 'extraActive': activityMultiplier = 1.9; break; default: activityMultiplier = 1.2; // Default to sedentary } var tdee = bmr * activityMultiplier; // Calculate daily calorie deficit needed for desired weekly loss var caloriesPerPound = 3500; // Approximately 3500 calories per pound of fat var dailyCalorieDeficit = (desiredWeeklyLoss * caloriesPerPound) / 7; // Calculate target daily calorie intake var targetDailyCalorieIntake = tdee – dailyCalorieDeficit; // Ensure target intake is not dangerously low (e.g., below 1200 for women, 1500 for men) var minRecommendedIntake = (gender === 'male') ? 1500 : 1200; var intakeWarning = "; if (targetDailyCalorieIntake < minRecommendedIntake) { intakeWarning = 'Warning: Your calculated target daily calorie intake is below the generally recommended minimum of ' + minRecommendedIntake + ' calories. This may not be healthy or sustainable. Please consult a healthcare professional.'; // Adjust target intake to minimum for display, but keep original for time calculation if user insists // targetDailyCalorieIntake = minRecommendedIntake; // Decided against forcing this, just warn. } // Calculate total weight to lose var totalWeightToLose = currentWeight – targetWeight; // Calculate estimated time to reach goal var estimatedWeeks = totalWeightToLose / desiredWeeklyLoss; var estimatedMonths = estimatedWeeks / 4.33; // Average weeks in a month resultDiv.innerHTML = `

Your Weight Loss Plan:

Estimated Maintenance Calories (TDEE): ${tdee.toFixed(0)} calories/day To lose ${desiredWeeklyLoss.toFixed(1)} lbs per week, you need a daily calorie deficit of approximately ${dailyCalorieDeficit.toFixed(0)} calories. Your recommended Target Daily Calorie Intake for weight loss is: ${targetDailyCalorieIntake.toFixed(0)} calories/day ${intakeWarning} To reach your target weight of ${targetWeight.toFixed(1)} lbs (losing a total of ${totalWeightToLose.toFixed(1)} lbs), it will take approximately: ${estimatedWeeks.toFixed(1)} weeks (or about ${estimatedMonths.toFixed(1)} months) Remember, these are estimates. Individual results may vary based on metabolism, adherence, and other factors. `; }

Understanding Your Weight Loss Journey with a Calculator

Embarking on a weight loss journey can feel overwhelming, but understanding the science behind it can make your goals more achievable. Our Weight Loss Goal Calculator is designed to provide you with a personalized roadmap, estimating how long it might take to reach your target weight and what your daily calorie intake should be.

How Does the Calculator Work?

This calculator uses established scientific principles to estimate your energy needs and the calorie deficit required for weight loss:

1. Basal Metabolic Rate (BMR): First, it calculates your BMR using the Mifflin-St Jeor equation. This is the number of calories your body burns at rest to maintain basic bodily functions (breathing, circulation, cell production, etc.). It considers your current weight, height, age, and gender.
2. Total Daily Energy Expenditure (TDEE): Your BMR is then multiplied by an activity factor to estimate your TDEE. This represents the total number of calories you burn in a day, including your BMR and the calories expended through physical activity.
3. Calorie Deficit for Weight Loss: To lose weight, you need to consume fewer calories than your body burns. This creates a "calorie deficit." Approximately 3,500 calories equals one pound of body fat. The calculator determines the daily calorie deficit needed to achieve your desired weekly weight loss (e.g., 1-2 lbs per week).
4. Target Daily Calorie Intake: By subtracting your required daily calorie deficit from your TDEE, the calculator provides an estimated target daily calorie intake for you to follow to achieve your weight loss goal.
5. Estimated Time to Goal: Finally, based on your total weight loss goal and your desired weekly loss rate, it estimates the number of weeks and months it will take to reach your target weight.

Why Use a Weight Loss Calculator?

• Set Realistic Goals: It helps you understand what's a healthy and achievable rate of weight loss.
• Personalized Calorie Targets: Provides a starting point for your daily calorie intake, tailored to your body and activity level.
• Motivation: Seeing an estimated timeline can be a powerful motivator to stick to your plan.
• Informed Decisions: Empowers you with data to make informed choices about your diet and exercise.

Key Factors Influencing Weight Loss

While calorie deficit is fundamental, several other factors play a crucial role in your weight loss journey:

• Diet Quality: Focusing on whole, unprocessed foods, lean proteins, healthy fats, and plenty of fruits and vegetables is more effective than just counting calories from unhealthy sources.
• Physical Activity: Regular exercise not only burns calories but also builds muscle, which boosts your metabolism, and improves overall health.
• Sleep: Adequate sleep (7-9 hours) is vital. Poor sleep can disrupt hormones that regulate appetite and metabolism, making weight loss harder.
• Stress Management: Chronic stress can lead to increased cortisol levels, which can promote fat storage, especially around the abdomen.
• Hydration: Drinking enough water can help with satiety and metabolism.
• Individual Metabolism: Everyone's body is different. Factors like genetics, age, and medical conditions can influence how quickly you lose weight.

Healthy Weight Loss Rates

Most health professionals recommend a gradual and sustainable weight loss of 1 to 2 pounds per week. This rate is more likely to result in long-term success and minimizes the risk of nutrient deficiencies or muscle loss. Rapid weight loss can often be unsustainable and may lead to a rebound effect.

Important Disclaimer

This calculator provides estimates based on general formulas. It is not a substitute for professional medical advice. Before starting any new diet or exercise program, especially if you have underlying health conditions, it is highly recommended to consult with a doctor, registered dietitian, or certified personal trainer. They can provide personalized guidance tailored to your specific health needs and goals.