There is no single number that works for everyone, but there is a straightforward way to find yours — and to understand why it changes as you go. This guide covers the calculation, the right size of deficit, and the mistakes that stall most people.
Your body burns calories even doing nothing. That part is your resting metabolic rate, usually 60–70% of the daily total. On top sits movement — walking, work, training — plus the energy used digesting food.
Added together these give your total daily energy expenditure, or TDEE. That is the number you need, because weight loss is simply eating below it consistently.
The most widely used formula is Mifflin-St Jeor. First the resting rate:
Then multiply by an activity factor:
| Activity level | Factor |
|---|---|
| Desk job, little or no exercise | 1.2 |
| Light — training 1–3× a week | 1.375 |
| Moderate — 3–5× a week | 1.55 |
| High — 6–7× a week | 1.725 |
A 30-year-old man, 80 kg, 178 cm, training three times a week:
That is his maintenance. To lose weight, he eats below it.
A kilogram of body fat is roughly 7,700 calories, which gives:
| Daily deficit | Estimated weekly loss |
|---|---|
| 300 calories | about 0.27 kg |
| 500 calories | about 0.45 kg |
| 750 calories | about 0.68 kg |
The usual recommendation is 15–20% below your daily burn. In the example above that is roughly 410–550 calories, so a target of 2,190–2,330 a day.
Why not go lower? The deeper the deficit, the greater the share of muscle lost alongside fat, and the harder hunger and fatigue hit. Weight comes off faster at first, but most people cannot hold it for more than a few weeks. A moderate deficit kept for six months beats an aggressive one abandoned after two.
As you lose weight you weigh less, so you burn less. Someone 8 kg down still eating their original target is no longer in a deficit at all. This is by far the most common cause of a plateau at the two-to-three month mark, and it has nothing to do with a "broken metabolism".
The fix is to recalculate every few kilograms. The guide on calculating your calorie target covers exactly when.
Cooking oil, a bite off someone else's plate, a spoon of peanut butter. These add up to 200–400 uncounted calories a day, which is the size of the deficit itself.
Research consistently finds people underestimate what they eat, often substantially. You don't have to weigh food forever, but a week or two of accurate logging calibrates your eye for everything after.
Daily weight moves with salt, carbs, water and digestion. A kilogram swing overnight is normal and means nothing. The weekly trend is the signal.
Achalti calculates your personal calorie target from your height, weight, age and activity level, and updates it automatically as your weight changes. Logging a meal takes seconds — type a sentence or photograph the plate.
This guide is general information based on mainstream nutrition recommendations. It is not personal medical or dietary advice. Before making significant dietary changes, particularly with an existing medical condition or during pregnancy, consult a doctor or registered dietitian.