Updated: October 2026
In short: A calorie deficit arises when you eat less energy than you burn. For healthy weight loss, the NHS and Verbraucherzentrale name a moderate deficit of about 500 to 600 kcal per day, which corresponds to roughly 0.5 to 1 kg of weight loss per week. Here's how to calculate it: estimate your basal metabolic rate, multiply by the activity factor to get your total requirement and subtract 500 to 600 kcal.
A calorie deficit sounds like maths, but it's done in three steps. We work it out for you with three examples, show you how much deficit makes sense and honestly say where the calculating reaches its limits.
What is a calorie deficit?
A calorie deficit means you take in less energy over the day than your body uses. The body gets the difference from its reserves. The Verbraucherzentrale puts it plainly on metabolism diets: a calorie remains a calorie, and special food combinations change nothing about that.
That is not a call to count every calorie. It just means: without a deficit, whether deliberate or through habits like fewer snacks between meals, you won't lose weight. How your energy use is made up is explained in our article How to Boost Your Metabolism.
How do you calculate your calorie deficit in 3 steps?
First the basal metabolic rate, second the total requirement, third the deficit. The basal metabolic rate is the energy your body uses at complete rest. Our calorie calculator uses the Mifflin and St Jeor formula for this.
- Basal metabolic rate: 10 times weight in kg, plus 6.25 times height in cm, minus 5 times age, then plus 5 (men) or minus 161 (women).
- Total requirement: basal metabolic rate times activity factor (PAL). Almost only sitting is 1.2, mostly sitting 1.4, walking or standing with some sport 1.6, regularly sporty 1.8.
- Deficit: subtract 500 to 600 kcal from the total requirement. The result is your daily amount for weight loss.
The value is an estimate. After two to three weeks, check on the scale and in daily life whether it fits, then correct it in small steps.
What does the calculation look like with three examples?
Here's the calculation for three profiles with a mostly sedentary daily routine (PAL 1.4). The values are rounded.
| Profile | Basal metabolic rate | Total requirement | For weight loss (minus 500 kcal) |
|---|---|---|---|
| Woman, 35 years, 70 kg, 172 cm | approx. 1,440 kcal | approx. 2,010 kcal | approx. 1,510 kcal |
| Man, 40 years, 90 kg, 180 cm | approx. 1,830 kcal | approx. 2,560 kcal | approx. 2,060 kcal |
| Woman, 50 years, 80 kg, 165 cm | approx. 1,420 kcal | approx. 1,990 kcal | approx. 1,490 kcal |
You can see: the deficit is the same for everyone, but the target amount differs markedly. There is no blanket figure like 1,200 kcal for everyone. Enter your values into the calorie calculator to get your number.
How big should the calorie deficit be?
The NHS advises losing weight steadily and aiming for about 0.5 to 1 kg per week. The Verbraucherzentrale names a deficit of about 500 to 600 kcal per day for this, combined with behaviour change and exercise. A bigger deficit puts weight on the scale faster at first, but part of it is water.
The NHS explicitly warns against crash diets because they are hard to stick to and often lead to the yo-yo effect. If you want to lose a lot of weight, talk to your doctor.
How do you put the deficit into practice in daily life?
Most simply through small, lasting adjustments instead of deprivation. The NHS recommends replacing sugary drinks with water, reducing sugar and fat, reading nutrition labels and not skipping meals, because that promotes cravings.
| Adjustment | Typical saving |
|---|---|
| Replace sugary drinks with water or unsweetened tea | 100 to 200 kcal per glass, depending on the drink |
| Slightly smaller portion on the plate | often 100 to 200 kcal per meal |
| Replace a snack with fruit or vegetables | often 100 to 250 kcal |
| 20 to 30 minutes of brisk walking | about 100 to 150 kcal, depending on weight |
The numbers are rough guides. You'll find more everyday ideas in the article Basic Rules of Weight Loss.
When should you not run a calorie deficit?
A deficit is not recommended during pregnancy and breastfeeding, with a past or present eating disorder, if you're underweight and for children and teenagers. With diabetes, heart, kidney and liver disease or regular medication too, planning belongs in medical hands.
The NHS advises talking to your GP if you suspect an eating disorder or are looking for support with weight loss.
How long can you stay in a deficit?
Until you've reached your goal, but without the expectation of being perfect every day. Occasionally plan maintenance phases in which you hold your weight. Many people keep a moderate deficit up well for weeks to months if it isn't too strict and there is room for enjoyment.
After that, it's about maintenance: the total requirement from step two is then your target. If you fall back into old habits, you usually gain weight again, as the Verbraucherzentrale also shows with the yo-yo effect.
Matching picks from frank.
If you'd like a short reset as a starting point: frank. Juice Cleanses provide 650 to 845 kcal per day depending on the level, and a fixed structure. Whether that's good for weight loss is covered in Can I Lose Weight With a Juice Cleanse?
You might also like
- How Many Calories Do You Need Per Day to Lose Weight Healthily?
- Basic Rules of Weight Loss
- How Useful Is Calorie Counting?
Frequently asked questions about calculating a calorie deficit
How many calories do I need to cut to lose 1 kg?
A fixed number is a rule of thumb and varies individually. The Verbraucherzentrale's guidance helps in practice: a deficit of 500 to 600 kcal per day leads to about 0.5 to 1 kg per week if you keep it up consistently.
Do I have to count calories to lose weight?
No, but a rough overview helps at the start. Many people manage without an app with fixed meals, smaller portions and fewer sugary drinks.
What is my basal metabolic rate?
It depends on weight, height, age and sex. The calorie calculator estimates it with the Mifflin and St Jeor formula.
Does a deficit of 1,000 kcal per day make sense?
Not for most people. It is hard to stick to and can lead to nutrient deficiency. The NHS advises steady weight loss of 0.5 to 1 kg per week.
Do drinks count towards the calorie deficit?
Yes, juices, soft drinks, milky coffee and alcohol contain calories. Water and unsweetened tea practically don't count.
How can I tell if my deficit is too big?
Warning signs are persistent tiredness, dizziness, cravings and irritability. If so, increase the amount a little and talk to a doctor if in doubt.
Note: This article is for general information and is not a substitute for medical or therapeutic advice. If you have complaints, pre-existing conditions, are pregnant or take medication, please talk to your doctor first.
