Calorie Deficit Calculator
Calculate your daily calorie needs and the deficit required for weight loss.
*Note: Consuming fewer than 1,200 calories (women) or 1,500 calories (men) per day is not recommended without medical supervision.
What is a Calorie Deficit?
A calorie deficit occurs when you consume fewer calories than your body burns in a day. It is the fundamental principle behind weight loss. When your body doesn't get enough energy from food to sustain its current weight, it begins to burn stored energy—most commonly fat—to make up the difference.
How This Calculator Works
This tool uses the Mifflin-St Jeor Equation, currently considered the most accurate standard for calculating Basal Metabolic Rate (BMR). Here is the breakdown of the process:
- BMR Calculation: We determine the energy your body needs just to function at rest (breathing, heart rate, etc.).
- TDEE Calculation: We multiply your BMR by an activity factor to find your Total Daily Energy Expenditure.
- Deficit Application: We subtract the calories required to meet your specific weight loss goal (roughly 7,700 calories per kg of fat).
A 35-year-old male weighing 90kg at 180cm height with a moderate activity level has a TDEE of approximately 2,800 calories. To lose 0.5kg per week, he needs a daily deficit of 500 calories, making his target 2,300 calories per day.
How to Maintain a Healthy Deficit
While it may be tempting to cut calories drastically to see fast results, sustainable weight loss is usually achieved with a moderate deficit. A deficit of 500 to 1,000 calories per day typically results in 0.5kg to 1kg of weight loss per week.
Factors Affecting Your Results
1. Metabolic Adaptation: As you lose weight, your BMR naturally decreases because a smaller body requires less energy to move.
2. Muscle Mass: Muscle tissue burns more calories at rest than fat tissue. Strength training can help preserve muscle while in a deficit.
3. NEAT (Non-Exercise Activity Thermogenesis): Small movements like fidgeting, walking to the car, and standing contribute significantly to your daily burn.
Frequently Asked Questions
Is a 1,000-calorie deficit safe?
For most people, a 1,000-calorie deficit is aggressive but manageable if they have a high starting TDEE. However, ensure your total intake doesn't drop below the minimum safety thresholds (1,200 for women, 1,500 for men).
Do I need to track macros?
While the deficit is the primary driver of weight loss, protein intake is crucial for maintaining muscle mass, and healthy fats are necessary for hormone regulation.