How Fast Should You Lose Weight? Safe Rates, Explained
The fastest safe rate of weight loss is 0.5–1% of your body weight per week. For a 100 kg person, that is 0.5–1 kg a week. For a 70 kg person, it is 0.35–0.7 kg a week. That is the range recommended by most clinical guidelines, and it is the range this guide works with — because it is the pace at which the weight you lose is mostly fat, your muscle is protected, your hormones stay in reasonable shape, and the loss is something you can actually sustain for months. Anything faster is possible, but it comes with costs that are rarely worth paying.
The reason the rate is expressed as a percentage of body weight, rather than a fixed number of kilograms, is that a bigger body can safely lose more. A 120 kg person losing 1 kg a week is losing 0.8% — well inside the safe range. A 60 kg person losing 1 kg a week is losing 1.7% — well outside it, and likely losing muscle along with the fat. The percentage keeps the advice honest across body sizes.
Use the calculators for your own numbers
Find your maintenance calories with the TDEE Calculator and set your target with the Weight Loss Calculator — it shows what different deficit sizes mean for your weekly rate. The worked examples below cover three body weights — 70 kg, 90 kg and 110 kg — so you can find the row closest to your own weight and see what a safe rate looks like for you.
Related reading: Calorie Deficit Explained — How It Works and How Big It Should Be, Weight Loss Plateau — Why It Happens and How to Break Through, How to Lose Weight Safely, Weight Loss Calculator, TDEE Calculator, full guides section
The formula, shown and cited
The rate of loss follows from the size of the deficit. A kilogram of body fat stores roughly 7,700 kcal, so:
Weekly fat loss (kg) ≈ daily deficit (kcal) × 7 ÷ 7,700
A 500 kcal daily deficit gives 500 × 7 ÷ 7,700 ≈ 0.45 kg a week. A 300 kcal deficit gives about 0.27 kg a week. A 750 kcal deficit gives about 0.68 kg a week. Those are the theoretical figures; in practice, loss is slower than the maths predicts, because the body adapts and because some of the loss is water and lean tissue rather than fat.
Now apply the 0.5–1% rule at three body weights:
| Body weight | 0.5% per week | 1% per week | Daily deficit needed for 0.5% | Time to lose 10 kg at 0.5% a week |
|---|---|---|---|---|
| 70 kg | 0.35 kg | 0.70 kg | ~385 kcal | ~29 weeks |
| 90 kg | 0.45 kg | 0.90 kg | ~495 kcal | ~22 weeks |
| 110 kg | 0.55 kg | 1.10 kg | ~605 kcal | ~18 weeks |
The last column is the one people least want to read: losing 10 kg at a safe, sustainable pace takes four to seven months. That is not a failure of the method; it is the method. Anyone promising 10 kg in a month is promising a rate of 2–3% a week, which is well outside the safe range and almost certain to cost muscle and to rebound.
There is one important exception to the slow pace: the first week. When you start a diet, especially one that cuts carbohydrates, you lose glycogen and the water stored with it — each gram of glycogen holds about 3 g of water — so the first week's drop can be 1–3 kg. That is water, not fat, and it does not continue. Judge your rate from week two onwards, using weekly averages.
Why faster is not better
Losing weight faster than 1% a week has four costs. First, muscle loss: on a steep deficit, a larger share of the weight lost is lean tissue, and muscle is what keeps your metabolic rate up. Second, hunger and fatigue: a large deficit raises ghrelin, the hunger hormone, and lowers leptin, the satiety hormone, which makes the diet harder to sustain and the rebound more likely. Third, hormonal disruption: in women, very low energy availability can disturb menstrual cycles; in men, it can lower testosterone. Fourth, gallstones: rapid weight loss is a well-established risk factor for gallstones, particularly at rates above 1.5 kg a week.
None of this means you must lose weight slowly forever. It means the deficit should match the goal: a moderate deficit of 300–500 kcal a day, protein at 1.6–2.2 g/kg while dieting (Morton et al., 2018), and resistance training two or three times a week is the combination that keeps the loss mostly fat and mostly permanent. The safety floors apply throughout: never go below 1,200 kcal a day for women or 1,500 kcal a day for men without medical supervision, whatever your target rate.
How to set your pace
Start at the low end of the range — 0.5% a week — for the first month. That gives you time to learn the habits, find the foods that keep you full, and confirm that the deficit is sustainable. If you are losing steadily, feeling well, and your training is progressing, you can push toward 1% a week if you want faster results. If you are hungry all the time, tired, or losing strength, slow down: add 100–200 kcal back and accept a slower rate. The right pace is the fastest one you can sustain without misery, not the fastest one the maths allows.
Build in diet breaks. Every eight to twelve weeks, spend one to two weeks at maintenance calories. It restores appetite hormones, reduces fatigue, and makes the next phase easier. It also gives you practice at the skill that matters most in the long run — maintaining a weight, not just losing it.
What the rate does NOT tell you
A weekly rate tells you how fast the scale is moving. It does not tell you what you are losing, whether you are healthy, or whether the loss will last. A person losing 0.5 kg a week while lifting weights and eating enough protein is in a better position than a person losing 1 kg a week on a crash diet with no training, even though the second person is "winning" on the scale. And a rate that looks good for three weeks and then collapses into a binge is worse than a slower rate that holds for six months. Judge a diet by its average over months, not its best week.
Frequently asked questions
Is losing 1 kg a week safe?
It depends on your weight. For a 100 kg person, 1 kg a week is 1% — the top of the safe range. For a 60 kg person, it is 1.7% — too fast, and likely to cost muscle. Use the percentage, not the absolute number: 0.5–1% of your body weight a week is the safe range for most healthy adults.
Why did I lose 3 kg in my first week?
Mostly water. Cutting calories, especially carbohydrates, depletes glycogen stores, and each gram of glycogen holds about 3 g of water. The first week's drop is real weight, but it is not fat loss, and it does not continue at that pace. Judge your rate from week two onwards, using weekly averages.
Can I lose weight faster if I have a lot to lose?
Yes, somewhat. A heavier person has a higher maintenance intake and can run a larger absolute deficit while staying inside the 0.5–1% range — a 120 kg person can lose 1.2 kg a week safely, which is a larger number than a 70 kg person should aim for. But the percentage rule still applies: above 1% a week, muscle loss and rebound risk rise sharply at any weight.
What if I am losing weight too slowly?
First, check that you are actually in a deficit: track food honestly for a week, recalculate your TDEE at your current weight, and weigh daily for a weekly average. If the deficit is real but small, add 100–200 kcal of activity or cut 100–200 kcal of food. If you are already at the safety floor of 1,200 or 1,500 kcal, do not cut further — add activity instead, or accept the slower rate.
Is rapid weight loss dangerous?
It can be. Rates above 1.5 kg a week are associated with gallstones, muscle loss, hormonal disruption and a much higher chance of regaining the weight. Very-low-calorie diets below 1,200 kcal a day for women or 1,500 kcal a day for men should only be followed under medical supervision. If you are losing weight much faster than 1% a week without trying, see a doctor — unintentional rapid loss can be a sign of an underlying health problem.
How long will it take to reach my goal weight?
Divide the amount you want to lose by your weekly rate. Losing 10 kg at 0.5 kg a week takes 20 weeks; at 0.7 kg a week, about 14 weeks. Build in diet breaks — one to two weeks at maintenance every eight to twelve weeks — which adds a few weeks to the total but makes the plan far more likely to succeed. A realistic timeline is measured in months, not weeks.
Estimates only, not medical advice. Minimum safe intakes: 1,200 kcal/day women, 1,500 kcal/day men — consult a healthcare professional before a very-low-calorie diet.