A kilogram of body fat stores roughly 7,700 calories. A deficit of 500 calories a day removes about 1 kg of fat in 15 to 16 days; 1,000 a day about a week. Early weight loss is faster because of water, and the pace slows a little as you get lighter.
"How many calories to lose a kilo" is a simple question with a useful answer, as long as you know its limits.
The number: about 7,700
Body fat is not pure fat; it holds some water and tissue. One kilogram of it stores about 7,700 calories (often rounded to 7,000 to 8,000). To lose 1 kg of fat, you need a total deficit of about that much, spread over days or weeks.
How long does 1 kg take?
- Deficit of 300 a day: about 25 days
- Deficit of 500 a day: about 15 to 16 days
- Deficit of 750 a day: about 10 days
- Deficit of 1,000 a day: about 8 days
A deficit of 300 to 750 a day suits most people: steady progress, while keeping muscle and energy.
How to create the deficit
First find your maintenance calories, then:
- Eat less: for example, cut sweet drinks (a can of soft drink is about 140 calories), reduce oil, and eat a little less rice or bread.
- Move more: 10,000 steps burn roughly 300 to 500 calories depending on your weight.
- Combine both: easier than doing all of it with food.
A 500-calorie gap is usually one sweet drink, one tablespoon of oil and a 40-minute walk.
Why the scale does not follow the maths exactly
- The first week drops faster: fewer carbs and less salt release water, often 1 to 2 kg.
- Daily ups and downs: water and salt can move you a kilo in a day.
- Your burn falls slightly as you get lighter, so the same intake gives a smaller deficit over time.
- Estimates are not exact: labels, portions and calculators all have some error.
That is why you judge progress by weekly averages over two to four weeks, not single days.
Muscle vs fat
Only the fat part follows the 7,700 rule. If you lose muscle too, the scale may move faster but you lose the wrong tissue. Keep your protein high and lift weights.
The takeaway
About 7,700 calories for each kilo of fat: 500 a day is roughly a kilo every two weeks. Shulah turns your goal into small steps, each with a date, and tracks your food and steps toward the daily target.