What calorie deficit do you need to lose weight?
To lose 0.5 kg a week you need a deficit of about 550 kcal a day, and for 1 kg a week about 1,100 kcal a day, counting 7,700 kcal per kilogram.
The recommended pace for most adults is about 0.5–1 kg (1–2 pounds) a week (CDC), without eating below your basal metabolic rate.
How is the calorie deficit calculated?
The calculator first estimates your maintenance needs (TDEE) with the Mifflin-St Jeor formula and your activity factor, then subtracts the deficit that matches the pace you chose.
If the result would fall below your basal metabolic rate, the target stops at BMR and the calculator shows the real pace you can reach. If you also enter a goal weight, you see how many weeks it takes.
Formula
- Daily deficit (kcal) = pace (kg/week) × 7,700 ÷ 7
- Calories per day = TDEE − daily deficit, but at least BMR
- Weeks = (current weight − goal weight) ÷ pace
Worked example
A 40-year-old man, 180 cm and 85 kg, moderately active, needs 2,759 kcal a day to maintain his weight. For 0.5 kg a week, the deficit is 0.5 × 7,700 ÷ 7 = 550 kcal, so his target is about 2,210 kcal a day. To reach 80 kg he needs about 10 weeks.
What deficit matches each weight-loss pace?
| Pace | Deficit per day | Deficit per week | Suits |
|---|---|---|---|
| 0.25 kg/week | 275 kcal | 1,925 kcal | close to goal weight or just starting |
| 0.5 kg/week | 550 kcal | 3,850 kcal | the right pace for most people |
| 0.75 kg/week | 825 kcal | 5,775 kcal | when you have more weight to lose |
| 1 kg/week | 1,100 kcal | 7,700 kcal | the upper limit, only with a high starting weight |
Why don’t you lose exactly what the calculator says?
- The 7,700 kcal per kilogram rule is an approximation: as you lose weight, your energy use drops, so the pace slows over time (Hall et al., 2011).
- In the first 1–2 weeks the scale drops faster because of water and glycogen, then more slowly.
- Weight varies by 0.5–1 kg from day to day (salt, water, menstrual cycle); follow the weekly average.
- Maintenance needs are also an estimate; adjust the target after 2–3 weeks of logging.
When should you talk to a specialist?
Ask a doctor or dietitian before a calorie deficit if you have diabetes (especially on insulin), heart or kidney disease, are pregnant or breastfeeding, are under 18 or have had an eating disorder.
Talk to a specialist too if you want to lose more than 1 kg a week, if your BMI is over 35, or if your weight has not changed after a month in a deficit.
Working with a nutritionist? See how they follow you in Rod