What Is a Calorie Deficit?
Quick Answer
A calorie deficit means burning more calories than you eat in a day.
Formula: Calorie deficit = TDEE - Daily calorie intake
- A deficit of 500 calories per day produces approximately 0.5 kg (1 lb) of weight loss per week.
- A deficit of 250 calories per day produces approximately 0.25 kg loss per week (slower but sustainable).
- Do not eat below your BMR. Safe minimum: 1,200 kcal per day for women, 1,500 kcal for men.
A calorie deficit is the single most reliable mechanism for fat loss. Every credible weight management approach, from low-carb to Mediterranean to calorie counting, works because it creates a calorie deficit. Understanding how to calculate yours correctly makes the process measurable and sustainable. Use the TDEE Calculator and Calorie Calculator on CalConvs to find your personalised numbers.
Step 1: Find Your TDEE
Your Total Daily Energy Expenditure (TDEE) is the number of calories your body burns in a real day, including all activity. It is calculated from your BMR (resting calorie burn) multiplied by your activity level.
| Activity Level | Multiplier |
|---|---|
| Sedentary (desk job, minimal exercise) | BMR x 1.2 |
| Lightly active (exercise 1 to 3 days per week) | BMR x 1.375 |
| Moderately active (exercise 3 to 5 days per week) | BMR x 1.55 |
| Very active (hard exercise 6 to 7 days per week) | BMR x 1.725 |
| Extremely active (physical job plus daily training) | BMR x 1.9 |
Step 2: Calculate Your Calorie Target
| Goal | Daily Deficit | Expected Loss |
|---|---|---|
| Slow loss | TDEE - 250 calories | 0.25 kg (0.5 lb) per week |
| Standard loss | TDEE - 500 calories | 0.5 kg (1 lb) per week |
| Faster loss | TDEE - 750 calories | 0.75 kg (1.5 lbs) per week |
| Aggressive loss | TDEE - 1,000 calories | 1 kg (2 lbs) per week (not recommended long-term) |
| Maintain weight | Eat at TDEE exactly | No change |
Worked Example
Person: Woman, 30 years old, 75 kg, 165 cm, moderately active. BMR: approximately 1,547 calories. TDEE (x 1.55): approximately 2,398 calories per day. Goal: lose 0.5 kg per week. Calorie target: 2,398 - 500 = 1,898 calories per day.
How Many Calories Is 1 kg of Body Fat?
| Measure | Approximate Energy |
|---|---|
| 1 lb of body fat | 3,500 kilocalories |
| 1 kg of body fat | 7,700 kilocalories |
| 250 calorie daily deficit | 0.23 kg (0.5 lb) loss per week |
| 500 calorie daily deficit | 0.45 kg (1 lb) loss per week |
| 750 calorie daily deficit | 0.68 kg (1.5 lb) loss per week |
Calorie Deficit Guidelines by Country
- United Kingdom (NHS): A deficit of 500 to 600 calories per day for gradual weight loss. Men should not go below 1,900 calories; women not below 1,400 calories on a weight loss plan.
- United States (CDC): Reducing daily intake by 500 to 1,000 calories per day, aiming for 0.5 to 1 kg (1 to 2 lbs) of loss per week.
- Australia (NHMRC): A deficit achieved through a combination of increased activity and modest dietary reduction rather than severe restriction.
- India (ICMR): A modest deficit of 300 to 400 calories per day is recommended for most Indian adults due to smaller average body size.
Frequently Asked Questions
How big should my calorie deficit be?
A deficit of 300 to 500 calories per day is the most sustainable approach for most adults. This produces 0.3 to 0.5 kg of weight loss per week while preserving muscle mass and energy levels. Larger deficits increase the risk of muscle loss and nutritional deficiencies.
What happens if the calorie deficit is too large?
A deficit larger than 1,000 calories per day causes the body to break down muscle tissue alongside fat for energy. This reduces your BMR over time, making it harder to maintain weight loss and easier to regain weight when normal eating resumes.
Can I lose weight without counting calories?
Yes. Many people create a calorie deficit naturally by eating more protein, increasing vegetables, reducing processed food and moving more. Calorie counting is a useful tool for understanding intake but not the only path to sustainable weight loss.
How do I maintain a calorie deficit while eating enough protein?
Set your protein target first using the Protein Calculator. Then allocate the remaining calories to carbohydrates and fat using the Macro Calculator. Eating adequate protein (1.6 to 2.2 grams per kg of body weight) while in a calorie deficit helps preserve lean muscle.
Related Tools
- TDEE Calculator: find your total daily energy expenditure
- Calorie Calculator: personalised daily calorie target
- BMR Calculator: your resting calorie burn baseline
- Macro Calculator: protein, carbs and fat targets within your calorie budget