How the math works
A kilogram of body fat stores roughly 7,700 kcal (about 3,500 kcal per pound). To lose 0.5 kg per week you need a weekly deficit of about 3,850 kcal — 550 kcal per day below your maintenance. This calculator estimates maintenance with the Mifflin-St Jeor equation and your activity level, subtracts the deficit for your chosen rate, and projects the timeline to your goal.
Choosing a rate
- 0.25 kg/week — slow and almost effortless; best when you are already lean.
- 0.5 kg/week — the sweet spot for most people: meaningful progress, preserved muscle, livable hunger.
- 0.75–1 kg/week — aggressive; workable for higher starting body fat, but keep protein high and expect the last weeks to be hard.
Why real progress is bumpier than the projection
Two things bend the straight line. First, your TDEE drops as you get lighter — recalculate every 4–5 kg lost. Second, water masks fat loss: sodium, carbs, stress, and training all move the scale day to day. Weigh in a few times a week and judge the two-week trend, not this morning's number.
Keep lifting through the deficit and hold protein at cutting levels (1.8–2.4 g/kg) — that is what tells your body to burn fat instead of muscle.