What is a calorie deficit?
A calorie deficit means eating fewer calories than your body burns in a day. Your body makes up the gap from stored energy — mostly body fat, if you eat enough protein and keep training. It is the one thing every successful fat-loss diet has in common, whether it's called keto, intermittent fasting or “just eating clean”.
Your burn is your TDEE (total daily energy expenditure): resting metabolism plus digestion, daily movement and exercise. This calculator estimates it with the Mifflin–St Jeor equation, then subtracts the deficit your timeline needs.
How big should your deficit be?
Most people do best losing about 0.5–1% of body weight per week. Faster than that and you lose more muscle, feel hungrier and are more likely to rebound.
| Daily deficit | Approx. loss / week | Best for |
|---|---|---|
| 250–300 kcal | ≈ 0.25 kg | Already lean, or gaining muscle while losing fat |
| 400–550 kcal | ≈ 0.5 kg | Most people — sustainable and easy to stick to |
| 700–1,000 kcal | ≈ 0.75–1 kg | Higher body weight, short phases only |
We also never set a target below about 1,200 kcal (women) or 1,500 kcal (men) without supervision. Below this it is hard to meet protein, iron, calcium and fibre needs from ordinary food.
The 7,700 kcal rule — and why progress slows
A kilogram of body fat stores roughly 7,700 kcal, so a 550 kcal daily deficit works out at about 0.5 kg a week. It is a good planning number, but real weight loss isn't perfectly linear: as you get lighter your maintenance falls, and early weeks include water loss from lower carb stores.
Research using dynamic models (Hall et al., 2011) shows losses slow over time if intake stays the same. The fix is simple: re-run this calculator every 4–5 kg and adjust your target.
Easy deficit swaps in an Indian diet
| Swap | Saves about |
|---|---|
| 2 rotis without ghee instead of 2 with 1 tsp ghee each | ≈ 90 kcal |
| 1 katori rice instead of 2 at dinner | ≈ 130–150 kcal |
| Tea with less sugar (2 cups, 1 tsp less each) | ≈ 40 kcal |
| Roasted chana instead of a samosa | ≈ 120–150 kcal |
| Dal tadka with 1 tsp oil instead of 1 tbsp | ≈ 80 kcal |
| A 30-minute brisk walk | ≈ 120–170 kcal |
Two or three of these together cover a 400–500 kcal deficit without cutting out the foods you enjoy. See best Indian foods for weight loss and rice vs roti for more, or look up exact roti and rice calories per serving.
Keep muscle while you lose fat
- Protein: about 1.6–2.2 g per kg of body weight a day while dieting — use the protein calculator.
- Strength training: 2–4 sessions a week tells your body the muscle is still needed.
- Steps: daily walking raises your burn without much extra hunger — check it with the steps to calories calculator.
- Sleep: short sleep increases appetite and makes a deficit harder to hold.
Worked example: Ankit wants to lose 10 kg
Ankit is 30, 175 cm, 85 kg and lightly active. His estimated maintenance is about 2,470 kcal.
Goal: 75 kg in 20 weeks. 10 kg × 7,700 = 77,000 kcal ÷ 140 days = a 550 kcal daily deficit, so his target is about 1,920 kcal a day — roughly 0.5 kg (0.6% of his weight) a week. Realistic.
Goal: 75 kg in 6 weeks. That needs a 1,830 kcal daily deficit — below his 1,500 kcal floor and nearly 2% of his body weight a week. The calculator flags it and suggests about 12 weeks instead.
How this calculator works
Maintenance (TDEE) = Mifflin–St Jeor BMR × an activity factor (1.2 to 1.725). Daily deficit = kilograms to lose × 7,700 ÷ days in your timeline. Your target is TDEE minus the deficit, but never below 1,200 kcal (women) or 1,500 kcal (men).
We flag a plan as aggressive when it needs more than 1% of your current body weight per week, or a target below the floor. The suggested timeline is the slower of those two limits. Designed for adults; not suitable during pregnancy, breastfeeding, for under-18s, or with a history of eating disorders.
Sources
- Mifflin MD, St Jeor ST, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr, 1990.
- Hall KD, et al. Quantification of the effect of energy imbalance on bodyweight. Lancet, 2011.
- Helms ER, et al. A systematic review of dietary protein during caloric restriction in resistance trained lean athletes. Int J Sport Nutr Exerc Metab, 2014.
- ICMR–National Institute of Nutrition. Nutrient Requirements for Indians (2020): recommendation on energy requirement.
Frequently asked questions
Straight answers about this calculator. Educational only — not medical advice.
About 1,100 kcal a day (7,700 ÷ 7). That's too much for most people — it's only appropriate at higher body weights, and the calculator will warn you if it pushes you under a safe minimum. Around 0.5 kg a week is more sustainable.
For most adults, yes. A 500 kcal daily deficit gives roughly 0.5 kg of loss a week, which is fast enough to stay motivated and slow enough to protect muscle and keep hunger manageable.
Usually the deficit is smaller than you think: oil, sugar in tea and weekend meals are easy to underestimate. Water retention from salt, stress or your menstrual cycle can also hide fat loss for 1–2 weeks. Track for 3 weeks and compare averages before changing anything.
Not one-for-one. This calculator's activity level already includes your usual training. If you add a lot of extra activity, eat back about half of it at most.
Yes — smaller portions of rice and roti, more dal, vegetables and protein, fewer fried snacks and more walking all create a deficit. Counting is simply the most reliable way to know you're in one.
For some smaller, less active women it can be, short-term. For most men and active women it's too low. Going below 1,200 kcal without medical supervision makes it hard to meet nutrient needs.
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This calculator provides an estimate and isn't a substitute for individualised medical or dietary advice. Read our medical disclaimer and editorial policy.