How many calories should I eat to lose weight? (UK guide)

It is the most-asked question in weight loss: how many calories should I eat to lose weight? The honest answer is that there is a sensible starting estimate you can calculate in two minutes - and a more accurate number you can find from your own data within a couple of weeks. This guide covers both, so you start in roughly the right place and then dial it in.

The short answer

To lose weight, eat about 300–500 calories per day below your maintenance level (your TDEE). For many UK adults that lands roughly in the 1,500–2,000 kcal range for women and 1,800–2,400 for men, but it varies widely with size and activity, so treat any formula as a starting estimate. The reliable method is to log your food for one to two weeks while your weight is stable to find your true maintenance, then subtract 300–500. Aim to lose around 0.5–1% of body weight per week, and adjust in small steps based on your weekly weight trend rather than a single day.

What is maintenance (TDEE)?

Your TDEE - Total Daily Energy Expenditure - is the number of calories you burn in a day, including everything: your resting metabolism, daily movement, exercise, and even digesting food. Eat at your TDEE and your weight stays stable. Eat below it and you lose weight; above it and you gain. So every calorie target for weight loss starts from one question: what is your maintenance? Get that roughly right and the rest is simple subtraction.

How to estimate your starting calories

You can get a starting estimate from an online TDEE calculator, which uses your weight, height, age, sex, and activity level. It is a reasonable first guess, but remember it is an estimate - real-world expenditure varies a lot between people of similar stats. From your estimated maintenance, set your deficit:

• Modest, sustainable loss: subtract around 300–400 kcal from maintenance.
• Faster loss (if you have more to lose): subtract around 500 kcal - but watch energy and training quality.
• Avoid very aggressive deficits: cutting 750–1,000+ kcal tends to cost muscle, wreck your mood and sleep, and become impossible to sustain.
• Keep protein high throughout - it protects muscle and keeps you full in a deficit.

The accurate method: find your real numbers

Calculators are a starting hypothesis; your own data is the truth. The most reliable way to find your maintenance is to log your food honestly for one to two weeks while your weight is roughly stable. Whatever you averaged is close to your real maintenance - far more accurate than any formula, because it reflects your actual metabolism and movement. From there, subtract 300–500 kcal and you have a target tailored to you, not to a population average.

This is exactly why food logging is worth the effort: it replaces guesswork with personalised numbers. Our beginner's guide to calories and macros walks through how to log without obsessing.

How do you know if your calorie target is working?

Judge it by your weekly weight trend, not the daily scale. Weigh in on several mornings a week, average them, and compare week to week. If you are losing roughly 0.5–1% of body weight per week, your target is right - leave it alone. If the trend has been flat for two to three weeks and fat loss is the goal, reduce calories by a small 100–200 kcal step. If you are losing too fast or feeling drained, eat a little more. One change at a time, then reassess after two to three weeks.

Frequently asked questions

How many calories should I eat a day to lose weight?

Aim for about 300–500 calories below your maintenance (TDEE). The exact number depends heavily on your size and activity, so start from a TDEE estimate or - more accurately - from logging your food for a couple of weeks at stable weight. Then subtract 300–500 and adjust based on your weekly weight trend. For many UK adults the result falls somewhere between 1,500 and 2,400 kcal, but yours may sit outside that range.

Is 1,200 calories a day enough to lose weight?

For many people 1,200 calories is unnecessarily low and hard to sustain, often leading to muscle loss, low energy, and rebound eating. Unless you are very small or advised by a professional, a more moderate deficit from your actual maintenance is usually more effective because you can stick to it. Slower, sustainable loss beats an aggressive cut you abandon.

Why am I not losing weight in a calorie deficit?

The most common reason is that the deficit is not as big as it seems - untracked oils, drinks, sauces, and weekend meals add up quickly. Water retention can also mask fat loss for a week or two. Tighten your logging, give it two to three weeks of a consistent weekly average, and if the trend is still flat, reduce calories by a small step. Judge by the multi-week trend, not a single day.

Find your numbers in one app

Go Gym keeps food logging fast with barcode scanning and clear calorie totals, and sits it next to your weight trend so you can find your real maintenance and see whether your target is working - all in one all-in-one fitness tracker built in the UK, with no paywall on the basics. Join the UK waitlist on the home page for early access.