A calorie deficit means eating fewer calories than your body burns in a day, so your body draws on stored energy, including body fat, to cover the gap. To calculate one, work out your total daily energy expenditure (TDEE) and eat about 250 to 750 kcal less than that, without going below 1,200 kcal a day.
That is the whole idea. The rest of this guide explains where those numbers come from, why the popular “7,700 kcal per kg” rule is only a rough guide, and how to pick a deficit you can actually live with.
What does calorie deficit mean in Hindi?
In Hindi, calorie deficit is simply “कैलोरी की कमी” (calorie ki kami).
Calorie deficit kya hai? Simple words mein: jitni calorie aapka body din bhar mein kharch karta hai, usse thoda kam khana. Jab khana kam aur kharch zyada hota hai, body apni jama ki hui energy (fat) use karti hai.
A deficit is not a diet. You can create one eating dal, roti, rice and sabzi, as long as the total is a little below what you burn. Moving more (walking, steps, exercise) also adds to the deficit.
What are BMR and TDEE?
BMR (basal metabolic rate) is the energy your body uses at complete rest just to keep you alive: breathing, heartbeat, temperature and organ function. For most people it is the largest part of daily energy use.
TDEE (total daily energy expenditure) is everything you burn in a day: your BMR plus all movement, work and exercise. ICMR-NIN calculates it as TEE = BMR × PAL, where PAL is your physical activity level.
The FAO/WHO/UNU expert report groups lifestyles by PAL like this:
| Lifestyle | PAL (TDEE divided by BMR) |
|---|---|
| Sedentary or light activity | 1.40 to 1.69 |
| Active or moderately active | 1.70 to 1.99 |
| Vigorous or vigorously active | 2.00 to 2.40 |
For Indians, ICMR-NIN’s 2020 report uses a PAL of 1.40 for sedentary adults, lower than the 1.53 used in 2010, because studies in India found that daily activities cost Indians less energy. The same report notes that the international FAO/WHO/UNU equations can overestimate BMR in Indians by 10 to 12%. Any calculator result is an estimate, so treat it as a starting point.
Should I use TDEE or BMR for a calorie deficit?
Use TDEE. Your deficit is the gap between what you eat and what you actually burn, and you burn your TDEE, not your BMR.
If you subtract 500 kcal from your BMR instead, you are also cutting out all the energy you use for daily activity, so your real deficit becomes much bigger than 500. That can mean eating far too little, feeling exhausted and giving up within weeks.
There is no need to eat below your BMR to lose weight. A moderate cut from TDEE is enough.
How do I calculate my calorie deficit?
Calorie deficit kaise calculate kare? Teen steps: BMR nikalo, usse activity se multiply karke TDEE nikalo, phir TDEE mein se 250 se 750 kcal kam karo.
Here is a worked example using the Mifflin-St Jeor equation, one of the common BMR formulas (Mifflin et al., 1990). For women: BMR = (10 × weight in kg) + (6.25 × height in cm) minus (5 × age in years) minus 161. For men, add 5 instead of subtracting 161.
Take a 30-year-old woman, 160 cm tall, weighing 70 kg, with a desk job:
- BMR = 700 + 1,000 minus 150 minus 161 = 1,389 kcal
- TDEE at ICMR’s sedentary PAL of 1.40 = 1,389 × 1.40 = about 1,945 kcal
- Target with a 500 kcal deficit = about 1,445 kcal a day
With a 250 kcal deficit her target would be about 1,695 kcal. With 750 kcal it would be about 1,195 kcal, just under 1,200, which is too low. For her, a 250 to 500 kcal deficit, plus more walking, is the sensible range.
The calorie deficit calculator does this for you, and the TDEE calculator shows your BMR and TDEE side by side.
How much calorie deficit do I need to lose 1 kg?
The classic rule says a cumulative deficit of 3,500 kcal removes one pound of body weight, which equals about 7,700 kcal per kg (32.2 MJ per kg, as Hall, 2008, puts it). On paper, that gives:
| Daily deficit | Weekly deficit | Weight loss per week on the rule of thumb |
|---|---|---|
| 250 kcal | 1,750 kcal | about 0.23 kg |
| 500 kcal | 3,500 kcal | about 0.45 kg |
| 750 kcal | 5,250 kcal | about 0.68 kg |
| 1,100 kcal | 7,700 kcal | about 1 kg |
So losing 1 kg a week needs a deficit of about 1,100 kcal every day. That is larger than most guidelines recommend. Losing 1 kg a month needs only about 260 kcal a day, which is far easier to sustain.
These are the maths, not a promise. Real results vary, as the next section explains.
Why does the 7,700 kcal rule stop working?
The rule assumes every kilogram you lose has the same energy content and that your energy needs stay fixed. Neither is true.
- What you lose varies. Hall (2008) showed the energy in lost weight depends on how much body fat you start with. The rule roughly fits people with plenty of body fat but overstates the deficit needed per kg for leaner people, because more of their loss comes from lean tissue, which holds less energy than fat.
- Your TDEE falls as you lose weight. A lighter body burns less, so the same calorie intake produces a smaller deficit over time. Hall and colleagues (2011) estimated that each permanent change of 100 kJ (about 24 kcal) a day leads to an eventual weight change of about 1 kg, with half of it reached in about a year and 95% in about three years.
In practice, weight loss is usually faster in the first weeks (partly water) and slows later. That is normal, not failure. Recalculate your TDEE every few kilograms, and use the weight loss date calculator to see a realistic timeline.
How big a calorie deficit is safe?
For most healthy adults, a deficit of 250 to 750 kcal a day is a sensible range:
- ICMR-NIN’s 2024 guidelines describe typical weight-loss diets as a 500 to 750 kcal a day deficit, consider losing about half a kilogram a week safe, and advise against going beyond a 40% deficit of daily energy needs. They also say weight-reduction diets should not go below 1,000 kcal a day and should provide all nutrients.
- The 2013 AHA/ACC/TOS obesity guideline suggests either a 500 or 750 kcal a day deficit, or about 1,200 to 1,500 kcal a day for women and 1,500 to 1,800 kcal a day for men. It reserves very low calorie diets (under 800 kcal a day) for medical settings with supervision.
Calo AI’s targets follow the same logic: you choose a 250, 500 or 750 kcal deficit (relaxed, steady or aggressive), and the app never sets a target below 1,200 kcal for women or 1,500 kcal for men.
Protein matters more during a deficit. ICMR-NIN notes that higher protein intake may help preserve muscle on a 500 to 750 kcal deficit. See how much protein per day for numbers, and how many calories should I eat a day for your maintenance figure.
Safety note: do not go below 1,200 kcal a day without medical supervision. If you are pregnant or breastfeeding, under 18, or have diabetes, PCOS, kidney disease or a history of an eating disorder, speak to a doctor or registered dietitian before starting a calorie deficit.
Practical takeaway
- Start from TDEE, not BMR. Your deficit is measured against what you actually burn.
- Pick 250 to 500 kcal if you are small or sedentary, and up to 750 kcal only if your target stays above 1,200 kcal (women) or 1,500 kcal (men).
- Use 7,700 kcal per kg as a rough guide only. Expect progress to slow as you get lighter.
- Judge by the trend over two to four weeks, not daily weigh-ins, and recalculate as your weight changes.
- Keep protein up and keep moving. Both help you lose fat rather than muscle.