How Many Calories Should You Eat to Lose 1 kg in a Week?

One kilogram of body fat stores roughly 7,700 calories. To lose 1 kg per week you need a daily calorie deficit of about 1,100 calories. That's the math. The harder question is whether that's safe and sustainable for you.

The math, in plain English

Energy in vs. energy out. If your maintenance is 2,200 kcal/day and you eat 1,100 kcal/day, you'll lose roughly 1 kg of fat per week. But this only works if the deficit is achievable without trashing your sleep, mood, or training.

Why blanket "lose 1 kg/week" advice often fails

Your TDEE isn't fixed. It drops as you lose weight. A deficit that worked at 80 kg won't move the scale at 75 kg.
1,100 kcal/day deficit is aggressive. For most adults under 80 kg, a sustainable deficit is closer to 500–800 kcal/day, which means 0.5–0.8 kg/week.
You don't burn what your tracker says. Wearable calorie estimates have a ±20% error band.

The honest answer: aim for 0.5–1% of bodyweight per week

Sports-nutrition research consistently lands on 0.5–1% of body weight per week as the sweet spot for weight loss without losing muscle. For an 80 kg person, that's 0.4–0.8 kg/week. Faster than that and you'll lose more muscle, get hungrier, and rebound harder.

How Zafit AI sets your target

Inside the Zafit app, your weight-loss plan is calculated from four inputs:

Your current weight, height, age, sex (for BMR via Mifflin-St Jeor).
Your activity level (for TDEE multiplier).
Your goal weight and a realistic timeline.
Your recent sleep and recovery (we don't push hard deficits on bad-sleep weeks).

Then we cap the deficit at a sustainable level and adjust nightly. No starvation plans, no impossible promises.

What 1,100 kcal/day looks like in food

For most people that's 3 small meals + 1 snack. Examples:

Breakfast: 2 boiled eggs + Greek yogurt + an apple — ~280 kcal
Lunch: grilled chicken (150g) + 1 cup brown rice + salad — ~450 kcal
Snack: handful of almonds — ~120 kcal
Dinner: dal (1 cup) + 2 chapati + sabzi — ~400 kcal

Total: 1,250 kcal — close enough.

Common mistakes

Cutting protein. Below ~1.6 g/kg you start losing muscle. Keep protein high.
No strength training. Without resistance training, ~25% of your loss will be lean mass.
Crash dieting on weekdays, splurging on weekends. Net deficit ≈ 0. Be consistent.
Ignoring sleep. 6 hours/night cuts fat loss in half (study: Cedars-Sinai, 2010).

Frequently asked

Is losing 1 kg per week healthy?

For most adults with significant weight to lose, yes — short-term. For people closer to their goal weight, 0.5 kg/week is more sustainable and preserves more muscle.

Can I lose 1 kg per week without exercise?

Yes, but you'll lose more muscle. Even two strength sessions per week dramatically reduce muscle loss during a deficit.

Why am I not losing weight on a deficit?

Either the deficit isn't real (under-tracking food, over-tracking exercise) or your TDEE has dropped (metabolic adaptation). Recalibrate every 3–4 weeks.