Calorie Deficit: How to Calculate One and Lose Weight Without Starving

A calorie deficit is when you eat fewer calories than your body burns. To calculate one, work out your daily calorie needs and subtract 300-500 kcal. This can help you lose about 0.3-0.5 kg per week without crash diets or running on empty.

Below, you’ll find a step-by-step guide, sample calculations, safe limits, and tips to help you stick with a calorie deficit beyond Thursday.

What is a calorie deficit?

Your body uses energy all the time—for breathing, keeping your heart and brain working, digestion, movement, and exercise. If it gets less energy than it uses, it makes up the difference from its reserves, mainly body fat.

It’s estimated that 1 kg of body fat equals about 7000-7700 kcal. This is a simplification, but it gives you an idea of the scale: to burn 1 kg of fat, you need a total deficit of around 7000 kcal spread over many days. You can’t do that over a weekend—and that’s a good thing, because crash diets rarely end well.

In the first week of weight loss, the number on the scale often drops faster than the calculations would suggest. This is mostly water and glycogen, not fat, so don’t judge your progress after just a few days, in either direction.

How do you calculate a calorie deficit?

1. Calculate your basal metabolic rate (BMR), for example using the Mifflin–St Jeor equation: 10 × weight (kg) + 6.25 × height (cm) - 5 × age, then subtract 161 (women) or add 5 (men).
2. Multiply your BMR by an activity factor: 1.2 if you have a sedentary job and don’t exercise, 1.375 if you work out 1-3 times a week, and 1.55 if you work out 3-5 times a week. The result is your daily calorie needs.
3. Subtract 300-500 kcal. That’s your daily calorie goal for weight loss.

Sample calculations:

The quickest way to calculate this is with the calorie deficit calculator—it also shows your estimated rate of progress and approximate date for reaching your goal. For a detailed explanation, including activity factor tables and examples, see our guide to calculating your daily calorie needs. We also explain how to review and adjust your goal after a few weeks in our guide to setting a calorie goal.

What is a safe calorie deficit?

A deficit of 300-500 kcal per day, or roughly 15-20% of your daily calorie needs, works well for most adults. A safe rate of weight loss is usually 0.5-1 kg per week—closer to the upper end for people with more excess weight and the lower end for leaner people.

A few guidelines to keep in mind:

• Without guidance from a specialist, don’t go below about 1200 kcal (women) or 1500 kcal (men),
• Don’t consume fewer calories than your BMR for a long time,
• If you lose more than about 1 kg per week for several weeks in a row, increase your calorie intake.

Talk to a doctor or dietitian about setting a calorie deficit if you have a chronic condition (such as diabetes or thyroid disease), take medication, are pregnant or breastfeeding, or have a history of eating disorders.

How much weight can you lose in a calorie deficit?

Assuming that 1 kg of fat equals about 7700 kcal, the estimated rate of weight loss looks like this:

In practice, weight loss can be faster in the first few weeks (due to water) and then slow down as you weigh less and burn fewer calories. So recalculate your daily calorie needs every few kilograms.

Calorie deficit and muscle: protein and training

When losing weight, you want to lose fat, not muscle. Two things can help:

• More protein—people who work out while losing weight usually need about 1.6-2.2 g of protein per kg of body weight per day, while people who don’t exercise need about 1.2-1.6 g/kg. Protein is also especially filling. Read more in our article on how much protein to eat per day.
• Strength training—2-3 workouts per week send your muscles a clear signal that they’re needed.

Add everyday movement, too: walks, stairs, cycling. Extra steps are an easy way to increase your deficit without taking food off your plate.

An example day at about 1500 kcal

Here’s what a day in a calorie deficit might look like for a woman whose daily calorie needs are about 1900-2000 kcal:

No going hungry: that’s four meals, plenty of protein and vegetables, and even a handful of nuts. If you don’t want to put together a meal plan yourself, the EatSee meal plan can build a day or a week around your calorie and protein goals, with recipes and a shopping list.

Why does a calorie deficit stop working?

After a few weeks of weight loss, your progress often slows down or stalls. This is normal and usually has one of these causes:

1. Underestimating — over time, you may become less accurate with logging, while oils, sauces, drinks, and snacking add up.
2. Lower calorie needs — a lower body weight means you burn fewer calories, so your previous calorie deficit gets smaller.
3. Less movement — when losing weight, we tend to move less without realizing it, which reduces energy expenditure.
4. Water — stress, salty foods, your menstrual cycle, or a new workout can hide fat loss for a few days.

What can you do? For two weeks, log absolutely everything, recalculate your daily calorie needs based on your current weight, and add more steps. If you've been losing weight for a long time, eating at your maintenance level for a week or two may also help — your mind needs a break, too.

How can you maintain a calorie deficit without feeling constantly hungry?

• Protein at every meal — eggs, dairy, meat, fish, and legumes.
• Plenty of vegetables — they add volume without many calories.
• Planning — when you know what you'll eat, you're less likely to reach for random snacks.
• Sleep — after a sleepless night, cravings for sweet and fatty foods increase.
• Fewer calories from drinks — juice, sugary drinks, and alcohol aren't very filling, and it's easy to go over your limit with them.

The most important rule: your calorie deficit should be sustainable for weeks at a time. It's better to lose weight more slowly than to experience a weight regain cycle.

This article is for informational purposes only and does not replace advice from a doctor or dietitian. Written by the EatSee editorial team. Editorial policy.