Health

How many calories do I need to burn to lose 1 kg?

The number is well established; what people get wrong is how long it takes and why the loss slows.

Losing 1 kg of body fat requires a cumulative energy deficit of roughly 7,700 kcal — about 7.7 kcal per gram, since fat tissue is roughly 87% lipid at 9 kcal/g. At a 500 kcal daily deficit that is about 15 days per kg, or roughly 2 kg a month. A 1,000 kcal daily deficit halves that to about 8 days, but is hard to sustain and starts costing muscle as well as fat.

Worked out 2026-09-04 (IST) · Approximately 7,700 kcal per kg of body fat; deficit sustained daily

How long 1 kg takes, by deficit

Time to lose 1 kg of fat at a sustained daily deficit
Daily deficit	Days per kg	Loss per week	Loss per month	Realistic?
250 kcal	30.8	0.23 kg	1.0 kg	Very sustainable
300 kcal	25.7	0.27 kg	1.2 kg	Very sustainable
500 kcal	15.4	0.45 kg	1.9 kg	Sustainable
750 kcal	10.3	0.68 kg	2.9 kg	Aggressive
1000 kcal	7.7	0.91 kg	3.9 kg	Hard to hold; risks muscle loss

Where a 500 kcal deficit actually comes from

Approximate figures for a 70 kg adult. Combining two small changes is easier than one large one.

Ways to create part of a daily deficit
Change	Approximate kcal
Drop one 330 ml sweetened soft drink	140
Swap 2 chapatis for 1	120
Skip a 40 g packet of fried snacks	210
Drop one 30 ml peg of spirits	65
Walk 45 minutes at a brisk pace	200
Run 30 minutes at 9 km/h	300
Cycle 45 minutes at a moderate pace	350

Aim for 0.5-0.75% of body weight a week. For a 70 kg adult that is about 0.35-0.5 kg a week, which corresponds to a 400-550 kcal daily deficit. Faster than 1% a week and a rising share of what you lose is muscle, which lowers your metabolic rate and makes the weight easier to regain.

Check your own numbers

Work out your maintenance calories first — the deficit is measured against that, not against a generic 2,000 kcal.

Calorie CalculatorAge, sex, weight, height and activity to your daily maintenance and weight-loss calories.

Frequently asked

Why do people say 3,500 calories per pound?

It is the same rule in imperial units. One pound is 0.4536 kg, and 7,700 kcal per kg works out to about 3,500 kcal per pound. Both numbers come from the same estimate of the energy stored in adipose tissue.

Why does weight loss slow down even when I keep the same deficit?

Because a lighter body burns fewer calories. Every kilogram lost lowers your basal metabolic rate and the energy cost of moving, so a deficit that was 500 kcal against your old maintenance is only 400-450 kcal against your new one. Recalculate maintenance every 4-5 kg, or the loss quietly stalls.

Is the 7,700 kcal rule exact?

It is a good planning approximation, not a law. Real loss includes water and glycogen early on — which is why the first week often shows 2-3 kg — and some lean mass later. Over months, actual loss usually runs a little behind the arithmetic prediction, which is normal and not a sign the deficit is failing.

Is it better to eat less or exercise more?

Diet creates a deficit far more efficiently. Skipping one 300 kcal snack takes a second; burning 300 kcal takes about 30-35 minutes of brisk running for a 70 kg adult. Exercise matters for preserving muscle, cardiovascular health and appetite regulation, but the deficit itself is won in the kitchen.

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