Nutrition & supplements
How long will it take to lose weight at your calorie deficit?
Days and weeks to reach your weight goal from daily calorie deficit — 7,700 kcal per kg of fat.
Quick answer
Fat loss obeys energy balance: about 7,700 kcal per kilogram of fat tissue. Lose 5 kg with a 500 kcal/day deficit → 5 × 7,700 ÷ 500 ≈ 77 days (~11 weeks) — not "5 weeks" unless the deficit is much larger.
Days to goal
77 days
- Weeks (approx.)
- ~11
- Total deficit needed
- 38,500 kcal
Rule of thumb: 1 kg of fat ≈ 7,700 kcal. A 500 kcal/day deficit loses about 0.45 kg/week — sustainable for many adults. Faster deficits need medical supervision; muscle loss rises below ~1,200 kcal intake for women / 1,500 for men.
How it works
A 500 kcal deficit is the classic sustainable target (~0.45 kg/week). Faster cuts lose more muscle and rebound harder; pair the timeline with adequate protein (1.6–2.2 g/kg) and resistance training. Track on a smart body composition scale weekly, not daily — water masks real fat loss.
Honest logging beats optimism: a food kitchen scale and meal prep containers expose the oils and sauces that turn a 500 kcal deficit into maintenance. Revisit TDEE after every 5 kg lost — lighter bodies burn less. Eating disorders, pregnancy or under-18: seek professional guidance before aggressive deficits. Planning tool only, not medical advice.
The timeline above assumes the deficit stays the same size, and it does not. A lighter body burns less, so the same food that created a 500 kcal deficit at the start creates perhaps 350 by the time you are eight kilos down — the finish date moves unless you recalculate every four or five kilograms. The start distorts things in the other direction: the first week often drops two kilos or more because each gram of stored glycogen holds around three grams of water with it. That comes off fast, does not come back while the deficit lasts, and makes weeks two and three look like failure when they are actually the normal rate. The deficit in the calculation is measured against maintenance, so recalculate it with the TDEE calculator every four or five kilograms — that is what keeps the finish date honest.
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Frequently asked questions
How long to lose 10 kg at 500 kcal deficit?+
10 × 7,700 ÷ 500 = 154 days — about 22 weeks. Plateaus and logging errors stretch real timelines; treat this as math, not a guarantee. As you get lighter, the same 500 kcal deficit represents a larger percentage of TDEE — expect the last 2 kg to move slower than the first.
Is a 1,000 kcal deficit safe?+
Only for very heavy individuals under supervision. For most adults it risks muscle loss, binge cycles and micronutrient gaps. 300–500 kcal is the usual sustainable range. Never drop below BMR without medical oversight — hunger, mood and sleep are early warning signs.
Why am I not losing weight on 500 kcal deficit?+
Common causes: underestimated eating, overestimated burn, water retention from new training, or metabolic adaptation. Re-check intake for two weeks with a scale; adjust deficit modestly, not drastically. Weekend untracked meals alone can erase a weekday deficit — log alcohol and cooking oils.
Does the 7,700 kcal rule include water weight?+
It approximates fat tissue only. Early diet weeks drop glycogen and water fast — the scale moves quicker than 7,700 kcal/kg predicts; fat loss rate stabilizes after 2–4 weeks. A refeed or high-carb day can add 1–2 kg of water overnight without gaining fat.
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