What Is a Calorie Deficit? How It Works and How Big It Should Be
A calorie deficit means eating fewer calories than you burn. Learn how big a safe deficit is, how fast you'll lose weight and how to keep it going.
By Ayoub Farid · · 2 min read
A calorie deficit is the one thing every weight loss method has in common, whether it's called keto, intermittent fasting or "clean eating". If you consistently eat fewer calories than your body uses, it draws on stored energy, mostly body fat, and you lose weight.
Key takeaways
- A deficit of about 300–500 kcal per day is a sustainable default for most people.
The basic idea
- Calories in: what you eat and drink.
- Calories out: your TDEE, which is your resting metabolism plus digestion, daily movement and exercise. See TDEE explained.
- Deficit: calories out − calories in.
If your TDEE is 2,200 kcal and you eat 1,800, your deficit is about 400 kcal per day.
How big should a calorie deficit be?
| Deficit per day | Typical result | Notes |
|---|---|---|
| 200–300 kcal | Slow, ~0.2–0.3 kg/week | Easiest to sustain |
| 300–500 kcal | Moderate, ~0.3–0.5 kg/week | Good default for most people |
| 500–750 kcal | Faster, ~0.5–0.7 kg/week | Harder; prioritize protein |
| 1,000+ kcal | Aggressive | Usually only with medical supervision |
These are estimates. The old rule that 3,500 kcal = 1 lb (or 7,700 kcal = 1 kg) of fat is a useful approximation, but weight loss slows over time as your body adapts and you get lighter.
Many people do well aiming to lose 0.5–1% of body weight per week.
Signs your deficit is too big
- Constant hunger, irritability and poor sleep
- Training performance dropping fast
- Losing more than ~1% of body weight per week for several weeks
- Thinking about food all day
How to make a deficit easier
- Eat enough protein: 1.2–1.6 g/kg. See how much protein do I need.
- Choose high-volume foods: vegetables, fruit, potatoes, soups. See volume eating.
- Keep drinks low-calorie.
- Walk more: daily steps add up. See calories burned walking.
- Track honestly, including oils and snacks.
How to calculate yours
Step-by-step with examples: how to calculate a calorie deficit. Meal ideas: calorie deficit meals.
Track it
Nutora calculates your daily target from your goal and pace, then shows how much is left after every meal photo.
Frequently asked questions
What is a good calorie deficit to lose weight?
About 300–500 calories per day is a sustainable starting point for most people.
How long until I see results in a calorie deficit?
Often 2–4 weeks for a clear trend, because daily weight fluctuates with water.
Can I lose weight without a calorie deficit?
No. Every diet that causes fat loss creates a deficit, even if it doesn't count calories.
Is a 1,000-calorie deficit safe?
It's aggressive for most people and best done with medical guidance.
Track it with a photo
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Nutora's AI estimates calories, protein, carbs and fat from a photo of your plate and tracks them against your daily goal. Download on iPhone and iPad with a 3-day free trial.
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