Scientific Calorie Deficit Calculator
Your Results
Your Base Metabolic Rate (BMR): calories/day
Maintenance Calories (TDEE): calories/day
To reach your goal, consume:
Note: It is generally not recommended for women to drop below 1,200 calories or men below 1,500 calories per day without medical supervision.
Understanding Calorie Deficit: The Science of Weight Loss
If you are looking to lose weight, you have likely heard the term "calorie deficit." But what does it actually mean, and how do you calculate it accurately? This guide breaks down the biological math required to transform your physique safely and sustainably.
What is a Calorie Deficit?
A calorie deficit occurs when you provide your body with fewer calories than it needs to maintain its current weight. When this happens, your body is forced to tap into stored energy sources—primarily body fat—to make up the difference. One kilogram of body fat contains approximately 7,700 calories. Therefore, to lose 1kg of fat, you must create a total deficit of 7,700 calories over a period of time.
How This Calculator Works
Our calculator uses the Mifflin-St Jeor Equation, which is currently considered the most accurate method for estimating metabolic rates in healthy adults. The process involves three steps:
- Basal Metabolic Rate (BMR): The number of calories your body burns at complete rest just to keep your organs functioning.
- Total Daily Energy Expenditure (TDEE): Your BMR multiplied by an activity factor (from sedentary to extra active). This is your "maintenance" number.
- The Deficit: We subtract the necessary daily calories required to reach your weekly weight loss goal (e.g., subtracting 550 calories daily for a 0.5kg/week loss).
Example Calculation
Imagine a 35-year-old male weighing 90kg at 180cm tall with a moderately active lifestyle. His stats might look like this:
- BMR: 1,880 kcal
- TDEE (Maintenance): 2,914 kcal
- Weight Loss Goal: 0.5 kg per week (Deficit of 550 kcal/day)
- Daily Target: 2,364 kcal
Tips for Success
Calculating the number is the easy part; sticking to it is where the challenge lies. To ensure success, focus on high-protein foods to preserve muscle mass and high-fiber vegetables to help you feel full. Remember that weight loss is rarely linear; water retention and hormonal changes can mask fat loss on the scale. Stay consistent for at least 3-4 weeks before adjusting your caloric intake.