A calorie deficit is the foundation of weight loss. This guide explains how to calculate your energy needs and create a sustainable deficit for healthy fat loss.
Understanding Calorie Deficit
The Basic Formula: Weight Loss = Calories In < Calories Out. One pound of body fat equals approximately 3,500 calories. A daily deficit of 500 calories results in about 1 pound lost per week.
Calculate Your TDEE
Total Daily Energy Expenditure (TDEE) is how many calories you burn per day:
TDEE Calculation
Step 1 - Calculate BMR:
Men: (10 × weight kg) + (6.25 × height cm) - (5 × age) + 5
Women: (10 × weight kg) + (6.25 × height cm) - (5 × age) - 161
Step 2 - Multiply by activity factor:
Sedentary: BMR × 1.2 | Light: BMR × 1.375 | Moderate: BMR × 1.55 | Active: BMR × 1.725
Activity Multipliers
| Activity Level | Description | Multiplier |
|---|---|---|
| Sedentary | Desk job, little exercise | 1.2 |
| Lightly Active | Light exercise 1-3 days/week | 1.375 |
| Moderately Active | Moderate exercise 3-5 days/week | 1.55 |
| Very Active | Hard exercise 6-7 days/week | 1.725 |
| Extra Active | Very hard exercise, physical job | 1.9 |
Recommended Deficit Sizes
| Deficit | Weekly Loss | Best For |
|---|---|---|
| 250 cal/day | 0.25kg/week | Already lean, slow approach |
| 500 cal/day | 0.5kg/week | Most people, sustainable |
| 750 cal/day | 0.75kg/week | Higher body fat percentage |
| 1000 cal/day | 1kg/week | Obese, medical supervision |
NHS Guidelines: The NHS recommends losing 0.5-1kg per week for sustainable weight loss. Very low calorie diets (under 800 calories) should only be followed under medical supervision.
Example: 35-year-old Woman
Weight: 75kg | Height: 165cm | Activity: Lightly active
BMR: (10×75) + (6.25×165) - (5×35) - 161 = 1,446 calories
TDEE: 1,446 × 1.375 = 1,988 calories
For 0.5kg/week loss: 1,988 - 500 = 1,488 calories/day
Minimum Safe Calories
- Women: Generally not below 1,200 calories/day
- Men: Generally not below 1,500 calories/day
- These are minimums - most people need more for adequate nutrition
Creating Your Deficit
- Diet alone: Reduce food intake by 500 calories
- Exercise alone: Burn extra 500 calories through activity
- Combined: Eat 250 less + burn 250 more (recommended)
Tips for Success
- Track your food: Use an app to log calories accurately
- Weigh weekly: Daily fluctuations are normal
- Eat protein: Helps preserve muscle, keeps you full
- Stay hydrated: Sometimes hunger is actually thirst
- Be patient: Sustainable loss takes time