Calorie Deficit Calculator for Weight Loss
Use this calculator to estimate your daily calorie needs and determine the calorie deficit required to achieve your weight loss goals. Understanding your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE) is crucial for effective and sustainable weight management.
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 a week)
Extra active (very hard exercise/physical job)
0.5 lbs (slow & steady)
1.0 lbs (recommended)
1.5 lbs
2.0 lbs (aggressive)
Understanding Calorie Deficit for Weight Loss
A calorie deficit occurs when you consistently consume fewer calories than your body burns. This forces your body to use stored energy (fat) for fuel, leading to weight loss. It's the fundamental principle behind losing weight.
How Your Body Burns Calories:
- Basal Metabolic Rate (BMR): This is the number of calories your body burns at rest to maintain basic bodily functions like breathing, circulation, and cell production. It accounts for the largest portion of your daily calorie expenditure.
- Thermic Effect of Food (TEF): Calories burned during the digestion, absorption, and storage of food. This typically accounts for about 10% of your total calorie intake.
- Activity Energy Expenditure (AEE): Calories burned through physical activity, including both structured exercise and non-exercise activity thermogenesis (NEAT) like walking, fidgeting, and standing.
Calculating Your Calorie Needs:
Our calculator uses the following steps to determine your calorie deficit:
- BMR Calculation: We use the Mifflin-St Jeor equation, which is widely recognized for its accuracy. It considers your gender, age, weight, and height.
- Total Daily Energy Expenditure (TDEE): Your BMR is then multiplied by an activity factor to estimate your TDEE. This is the total number of calories your body burns in a day, taking into account your exercise habits and daily movement.
- Desired Calorie Deficit: To lose weight, you need to create a deficit. Since approximately 3,500 calories equal one pound of fat, a daily deficit of 500 calories typically leads to a loss of one pound per week (500 calories/day * 7 days/week = 3,500 calories/week).
- Target Daily Calorie Intake: This is calculated by subtracting your desired daily calorie deficit from your TDEE. This number represents the approximate calorie intake you should aim for to achieve your weight loss goal.
Sustainable Weight Loss and Important Considerations:
- Realistic Goals: Aim for a gradual and sustainable weight loss of 0.5 to 2 pounds per week. More aggressive deficits can be harder to maintain and may lead to nutrient deficiencies or muscle loss.
- Minimum Calorie Intake: It's generally not recommended for women to consume fewer than 1200 calories per day, and men fewer than 1500 calories per day, without medical supervision. Very low-calorie diets can be detrimental to health.
- Nutrient Density: Focus on consuming nutrient-dense foods (lean proteins, fruits, vegetables, whole grains) to ensure you get essential vitamins and minerals, even while in a deficit.
- Exercise: While diet is key for creating a deficit, exercise helps burn additional calories, preserve muscle mass, and offers numerous other health benefits.
- Consult a Professional: Always consult with a healthcare provider or a registered dietitian before making significant changes to your diet or exercise routine, especially if you have underlying health conditions.
By understanding and managing your calorie deficit, you can make informed decisions to reach your weight loss goals effectively and healthily.
Please enter valid positive numbers for all fields.
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return;
}
var weightKg = weightLbs / 2.20462;
var heightCm = heightInches * 2.54;
var bmr;
// Mifflin-St Jeor Equation
if (genderMale) {
bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * age) + 5;
} else if (genderFemale) {
bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * age) – 161;
} else {
resultDiv.innerHTML = "Please select your gender.
";
return;
}
var tdee = bmr * activityLevel;
var dailyDeficit = (weeklyLossLbs * 3500) / 7; // 3500 calories per pound of fat
var targetCalories = tdee – dailyDeficit;
var resultHtml = "Your Calorie Deficit Plan:
"; resultHtml += "Your estimated Basal Metabolic Rate (BMR): " + Math.round(bmr) + " calories/day"; resultHtml += "Your estimated Total Daily Energy Expenditure (TDEE): " + Math.round(tdee) + " calories/day"; resultHtml += "To lose " + weeklyLossLbs + " lbs per week, you need a daily calorie deficit of approximately " + Math.round(dailyDeficit) + " calories."; resultHtml += "Your target daily calorie intake for weight loss: " + Math.round(targetCalories) + " calories/day"; // Add a warning for very low calorie intake if ((genderFemale && targetCalories < 1200) || (genderMale && targetCalories < 1500)) { resultHtml += "Warning: Your calculated target calorie intake is very low. Consuming fewer than 1200 calories (for women) or 1500 calories (for men) per day is generally not recommended without medical supervision, as it can lead to nutrient deficiencies and health issues. Consider a smaller weekly weight loss goal.
";
}
resultDiv.innerHTML = resultHtml;
}