How many calories should I eat to lose weight?

Work out your maintenance calories, then eat 300 to 600 kcal a day less than that. For many women that lands somewhere between 1,400 and 1,800 kcal, and for many men between 1,800 and 2,300 kcal, but your own number depends on your size and activity. Our free calorie calculator works it out for you.

How many calories are in a pound of fat?

A pound of body fat stores roughly 3,500 kcal, and a kilogram roughly 7,700 kcal. That is where the common advice of a 500 kcal daily deficit to lose about a pound a week comes from, although real-world weight loss usually slows over time.

Is a 1,000 calorie deficit too much?

For most people, yes. A deficit of 1,000 kcal a day is hard to sustain, makes it difficult to get enough protein and nutrients, and increases muscle loss. The NHS suggests aiming to lose 0.5 to 1 kg a week, which for most people means a deficit of about 500 to 600 kcal.

Why am I not losing weight in a calorie deficit?

The most common reasons are under-recording food (especially oils, drinks and snacks), overestimating activity, and water retention hiding fat loss on the scales. Track carefully for two to three weeks and compare weekly average weights before changing anything.

Can I lose weight without counting calories?

Yes, if something else creates a deficit, such as eating more protein and vegetables, cutting down on drinks and snacks, or eating smaller portions. Counting calories lets you check that the deficit is there.

Calorie deficit: how to work out yours and lose weight

To lose weight you need to eat fewer calories than you burn. This guide covers how to work out your calorie deficit, how big it should be, and what to do when your weight stops going down.

By the Calori team · Updated 21 October 2026 · 8 min read

What is a calorie deficit?

A calorie deficit means eating fewer calories than your body uses. To make up the difference, your body draws on stored energy, mostly body fat, and over time you lose weight. Low-carb, intermittent fasting, slimming clubs and meal replacements all work by creating a calorie deficit; they just get there in different ways.

Step 1: find your maintenance calories

Your maintenance calories, also called your TDEE (total daily energy expenditure), are the calories you burn in a day. They are made up of:

Basal metabolic rate (BMR): the energy to keep you alive at rest. This is usually 60 to 70% of the total.
Everyday movement: walking, standing, fidgeting, housework. This varies more than anything else between people.
Exercise: workouts, sport, runs.
Digesting food: around 10% of what you eat, a little more for protein.

You can estimate yours in under a minute with our calorie calculator. As a very rough guide, the NHS uses 2,500 kcal a day for men and 2,000 kcal for women.

Step 2: choose the size of your deficit

A kilogram of body fat holds around 7,700 kcal (about 3,500 kcal per pound). So a daily deficit of:

Daily deficit	Weekly deficit	Expected loss per week
250 kcal	1,750 kcal	about 0.25 kg (½ lb)
500 kcal	3,500 kcal	about 0.45 kg (1 lb)
750 kcal	5,250 kcal	about 0.7 kg (1½ lb)
1,000 kcal	7,000 kcal	about 0.9 kg (2 lb)

The NHS recommends aiming to lose 0.5 to 1 kg (1 to 2 lb) a week, and its weight loss plan is built around cutting roughly 600 kcal a day. For most people a deficit of 300 to 600 kcal works well. It is enough to see progress every few weeks and small enough to keep eating normal meals. A good rule of thumb is to lose no more than about 1% of your body weight a week.

Step 3: eat enough protein

When you eat less, your body can break down muscle as well as fat. Eating plenty of protein, around 1.6 to 2.2 g per kg of body weight, and doing some strength training two or three times a week makes sure most of what you lose is fat. Protein is also the most filling macronutrient, which makes a deficit easier to stick to. See how much protein you need and our high protein meal ideas.

Step 4: track, then adjust

Your target is an estimate, so treat the first few weeks as a test:

Log everything you eat and drink, including cooking oil, milk in tea and weekend drinks.
Weigh yourself three or more times a week, first thing in the morning, and look at the weekly average.
After two to three weeks, compare the averages. If they are not falling, reduce your target by 100 to 200 kcal.

Day-to-day weight jumps around by a kilo or more with water, salt and carbs. A single high reading after a takeaway is not fat gain, so look at the trend.

Why weight loss slows down

The 3,500-calories-per-pound rule works well for the first few weeks but overestimates long-term loss. As you get lighter you burn fewer calories, both at rest and when you move, and many people unconsciously move less when eating less. That is normal. When progress stalls for three weeks or more, recalculate your maintenance calories at your new weight, check your tracking is still accurate, or add more daily steps.

Common calorie deficit mistakes

Forgetting the extras. A tablespoon of olive oil is around 120 kcal. A large latte can be 200. They add up quickly.
Weekend overshoots. Five careful days and two big ones can wipe out the week. Look at your weekly total, not just weekdays. Our guides to calories in alcohol and calories in British food help here.
Cutting too hard. Very low targets lead to hunger, low energy and bingeing. A smaller deficit is easier to keep up.
Eating back all your exercise calories. Fitness trackers often overestimate calories burned. See how accurate Apple Watch calories are.

Make tracking easy

A calorie deficit only works if you know roughly what you are eating, and the hardest part of that is logging meals day after day. Calori makes it quicker: photograph your plate and it logs the calories and macros for you, shows what is left of your daily target, and lets friends keep you accountable. If you prefer a fixed plan, start with one of our calorie-controlled meal plans.

When to get advice. If you are pregnant, under 18, have diabetes or another medical condition, or have a history of disordered eating, talk to your GP before starting a calorie deficit.

Frequently asked questions

How many calories should I eat to lose weight?: Work out your maintenance calories, then eat 300 to 600 kcal a day less than that. For many women that lands somewhere between 1,400 and 1,800 kcal, and for many men between 1,800 and 2,300 kcal, but your own number depends on your size and activity. Our free calorie calculator works it out for you.
How many calories are in a pound of fat?: A pound of body fat stores roughly 3,500 kcal, and a kilogram roughly 7,700 kcal. That is where the common advice of a 500 kcal daily deficit to lose about a pound a week comes from, although real-world weight loss usually slows over time.
Is a 1,000 calorie deficit too much?: For most people, yes. A deficit of 1,000 kcal a day is hard to sustain, makes it difficult to get enough protein and nutrients, and increases muscle loss. The NHS suggests aiming to lose 0.5 to 1 kg a week, which for most people means a deficit of about 500 to 600 kcal.
Why am I not losing weight in a calorie deficit?: The most common reasons are under-recording food (especially oils, drinks and snacks), overestimating activity, and water retention hiding fat loss on the scales. Track carefully for two to three weeks and compare weekly average weights before changing anything.
Can I lose weight without counting calories?: Yes, if something else creates a deficit, such as eating more protein and vegetables, cutting down on drinks and snacks, or eating smaller portions. Counting calories lets you check that the deficit is there.