What is a safe calorie deficit?
Who this guide is not for
This guide is for healthy adults aged 18 and over. If you are pregnant or breastfeeding, have a medical condition such as diabetes or kidney disease, take regular medication, are underweight, or have ever had an eating disorder, speak with a doctor or registered dietitian before you cut calories. Stop and get advice if you feel faint, unwell or unable to function.
A safe calorie deficit is a modest, steady one. The CDC describes losing about 1 to 2 pounds (0.5 to 1 kg) a week as a gradual pace. Our calculators add their own limits: never more than 25% below maintenance calories, and never below 1,200 kcal (women) or 1,500 kcal (men) a day.
Calculators for this guide: Calorie Deficit Calculator · Calorie Calculator (TDEE) · Protein Calculator
What is a calorie deficit?
Your body uses a certain number of calories a day to stay alive and active. That figure is your maintenance level, also called total daily energy expenditure (TDEE). A calorie deficit means eating less than that, so the body makes up the gap from its energy stores. Our calorie calculator estimates your maintenance calories, and the calorie deficit calculator turns a goal weight and timeframe into a daily target.
A common rule of thumb is that about 7,700 kcal is the energy in one kilogram of body weight. Worked example: at 2,400 kcal maintenance, eating 1,900 kcal is a 500 kcal deficit. Over a week that is 500 × 7 = 3,500 kcal, which predicts 3,500 ÷ 7,700 = about 0.45 kg (1 lb) of loss.
| Daily deficit | Daily target | Predicted loss a week | Within our limits? |
|---|---|---|---|
| 250 kcal | 2,150 kcal | 0.23 kg (0.50 lb) | Yes |
| 500 kcal | 1,900 kcal | 0.45 kg (1.00 lb) | Yes |
| 750 kcal | 1,650 kcal | 0.68 kg (1.50 lb) | No: more than 25% below maintenance |
| 1,000 kcal | 1,400 kcal | 0.91 kg (2.00 lb) | No: more than 25% below maintenance |
Calculated at about 7,700 kcal per kilogram. The highlighted row is the common starting point.
How big can a calorie deficit safely be?
Our calculators apply three limits at the same time, and whichever is strictest wins:
- A calorie floor. Never below 1,200 kcal a day for women or 1,500 kcal for men.
- A share of maintenance. Never more than 25% below your estimated maintenance calories.
- A pace limit. Never planning for more than about 1 kg (2 lb) of loss a week. The CDC describes about 1 to 2 pounds a week as a gradual, steady pace.
These are our own editorial limits, designed to be cautious. They are not a clinical protocol, and a doctor or dietitian can tailor a plan to you.
Woman A is held at the 1,200 kcal floor. For Woman B and Man A the 25% limit is the strictest.
View the chart data as a table
| Example | Value (kcal) |
|---|---|
| Woman A: maintenance | 1,500 |
| Woman A: lowest target | 1,200 |
| Woman B: maintenance | 2,200 |
| Woman B: lowest target | 1,650 |
| Man A: maintenance | 2,800 |
| Man A: lowest target | 2,100 |
Try it: how big a deficit?
Enter your maintenance calories (find them with the calorie calculator), then drag the slider. The limits below are the ones our calculators apply. For healthy adults aged 18 and over.
kcal/day
kg
Why is a bigger deficit not better?
A larger deficit does not buy a faster result without a cost. Eating much less can make it harder to meet your nutrient needs, can leave you tired, irritable or lightheaded, and is harder to keep up, which often matters more than the size of the deficit. Rapid loss can also include more lean mass. Very low-calorie diets, usually 800 kcal a day or less, are used only under medical supervision.
If you are cutting calories, protein deserves attention. Our protein calculator shows a daily range for your weight and activity level.
Why does weight loss slow down?
As you lose weight, your body needs fewer calories, so the same deficit shrinks. The 7,700 kcal per kilogram rule is a short-term approximation. Research by Kevin Hall and colleagues showed that it overstates long-term loss, because energy needs fall as weight falls. Re-run the calorie calculator every few kilograms, or about every four weeks, with your new weight, and treat projected dates as a guide rather than a promise.
A safe-deficit checklist
Before and during a deficit
Tick what applies. Your ticks are saved in this browser only.
Calorie deficit: myth or fact?
Myth The bigger the deficit, the better.
Fact A faster pace is harder to sustain and can mean eating too little to meet your needs. That is why our calculators cap the deficit at 25% below maintenance and about 1 kg a week.
Myth 1,200 calories a day is the right target for everyone.
Fact 1,200 kcal is the lowest intake our calculators will show for women, not a goal. Your target depends on your maintenance calories, and the floor for men is 1,500 kcal.
Myth 3,500 calories always equals one pound lost.
Fact It is a rough rule of thumb (about 7,700 kcal per kilogram). It works over a few weeks, but real loss slows as your body needs less energy.
Test what you have learned
Calorie deficit quiz
Five questions. Pick an answer for instant feedback.
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Show the answer
Answer: 7,700. About 7,700 kcal per kilogram, which is roughly 3,500 kcal per pound.
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Show the answer
Answer: 1,200 kcal. The floor is 1,200 kcal for women and 1,500 kcal for men. It is a limit, not a target.
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Show the answer
Answer: 25%. Targets are never more than 25% below estimated maintenance calories.
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Show the answer
Answer: A lighter body needs fewer calories, so the deficit shrinks. As weight falls, maintenance calories fall too, so the same food intake produces a smaller deficit.
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Show the answer
Answer: Only under medical supervision. Very low-calorie diets are used only with medical supervision.
Frequently asked questions
How many calories should I cut to lose weight?
It depends on your maintenance calories. A deficit of about 500 kcal a day predicts roughly 0.45 kg (1 lb) a week. The calorie deficit calculator works out a daily target for your goal and keeps it within safe limits.
Is 1,200 calories a day safe?
1,200 kcal is the lowest intake our calculators will show for women, and it is not right for everyone. Many people need much more, and the floor for men is 1,500 kcal. Eating below your needs for long periods without guidance can be unsafe, so ask a doctor or dietitian.
Is a 1,000 calorie deficit too much?
For most people, yes. A 1,000 kcal deficit is more than 25% below maintenance unless maintenance is 4,000 kcal or more, and it predicts nearly 1 kg a week, close to the fastest pace we plan for.
How fast can I safely lose weight?
The CDC describes about 1 to 2 pounds (0.5 to 1 kg) a week as a gradual, steady pace. Our calculators never plan for more than about 1 kg a week.
Does exercise count towards a calorie deficit?
Yes. Exercise raises the calories you use, which can widen the gap without eating less. Choose your activity level honestly in the calorie calculator, and avoid counting the same exercise twice.
Who should not use a calorie deficit?
Children and teenagers, people who are pregnant or breastfeeding, and anyone underweight should not. If you have a medical condition, take medication or have had an eating disorder, speak with a doctor or dietitian first.
Calculators that go with this guide
More guides
Sources
- Steps for Losing Weight (opens in a new tab) — Centers for Disease Control and Prevention (CDC)
- Quantification of the effect of energy imbalance on bodyweight (opens in a new tab) — Hall KD et al. The Lancet, 2011;378:826–837
- Very low-calorie diets — National Task Force on the Prevention and Treatment of Obesity, NIH. JAMA, 1993;270:967–974
Disclaimer and editorial note
For information only, not medical advice. This calculator gives general estimates from the numbers you enter. It cannot diagnose, treat or prevent any condition and does not replace advice from a doctor, midwife, registered dietitian or other qualified professional who knows your history.
Written and maintained by the HealthFitnessHQ editorial team. We name the source of every figure and formula, and we review each guide when guidance changes. Read how we work in our editorial policy and methodology.