How to count calories:
a UK beginner's guide.

1. Know your number

Start with your maintenance calories, the amount that keeps your weight steady, then set a target a little under it to lose fat or a little over it to build muscle. The free calorie calculator does both in kg or stone, and the protein calculator gives you a protein target to go with it.

Body fat stores about 7,700 kcal per kg, so eating around 500 kcal a day under maintenance works out at roughly 0.5 kg a week. Slower is fine.

2. Read the label

UK food labels give energy and nutrients per 100 g (or 100 ml), and often per portion as well.

• Per 100 g or per portion. Per 100 g is always there, so it is the reliable one: weigh what you eat and work from that. The portion on the pack may not be the amount you actually have.
• kcal or kJ. Energy is shown in kilojoules (kJ) and kilocalories (kcal). Count the kcal: in the UK, "calories" means kcal. 1 kcal is 4.184 kJ, so 1,000 kJ is about 239 kcal.
• Reference intake. The "% RI" figures are based on 2,000 kcal (8,400 kJ) a day, a general figure for an adult. Your own target may be quite different.
• Traffic lights. The red, amber and green colours on the front of many packs are for fat, saturates, sugars and salt. They don't tell you how many calories to eat.

3. Weigh it, at least at first

A cheap digital kitchen scale makes counting far more accurate. Weigh food the way it is listed: if you log dry pasta, weigh it dry; if you log cooked rice, weigh it cooked. Pasta and rice soak up water as they cook and roughly double in weight or more, so mixing them up is one of the easiest ways to be out by hundreds of calories.

Oils, butter and spreads are easy to miss: a tablespoon of oil is about 120 kcal. Weigh them, or measure with a spoon. After a few weeks you will be able to judge your usual portions by eye and weigh only now and then.

4. Log as you go

Log each meal when you eat it, not at the end of the day from memory. Drinks count: milky coffees, juices, fizzy drinks and alcohol all add up. Food has 4 kcal per gram of protein or carbohydrate, 9 kcal per gram of fat, and alcohol has 7 kcal per gram.

5. Meal deals and supermarket food

Packaged food is the easiest thing to count, because it is labelled. For a meal deal, log the main, the snack and the drink as three items from their labels, and add them up. Supermarket websites list the nutrition for most products if you want to plan ahead.

6. Eating out and takeaways

In England, larger food businesses (those with 250 or more employees) have had to show calories on their menus since April 2022, so most chains now print them. At smaller places, or elsewhere in the UK, pick the closest match you can find and move on. One estimate won't make or break your week, and logging a guess is better than logging nothing.

7. The mistakes most beginners make

• Missing the small stuff: cooking oil, sauces, milk in tea, bites while cooking.
• Counting weekdays only. Two loose days can cancel out five careful ones.
• Trusting the pack portion instead of what is on your plate.
• Reacting to one weigh-in. Weight swings 1 to 2 kg a day with water and salt. Watch the weekly average.
• Cutting too hard. A big deficit is hard to keep up and costs muscle. About 0.5% of your body weight a week is plenty.

When counting isn't a good idea

If you have had an eating disorder, or counting makes you anxious about food, don't count. Talk to your GP, or contact Beat, the UK eating disorder charity. If you are pregnant, under 18 or have a medical condition, ask your GP or a registered dietitian first.

Counting calories without the admin

Most people give up counting because it takes too long. In Physiqo you type what you ate the way you'd say it, like 2 eggs on toast and a coffee, snap a photo of the plate, scan a barcode or send a screenshot of another app's food diary, and Ari works out the calories and macros.

It checks UK foods first: your usual foods, then UK chain menus, then more than 50,000 UK supermarket products stored on the phone, then the UK food table (CoFID). A confident match logs straight away with Undo; if she isn't sure, she asks you first. Fix a food once and it sticks. More in the calorie counter app guide.

Plans and availability

Physiqo is £14.99 a month, £29.97 for 3 months or £95.88 for 12 months, after a free trial whose length the App Store sets. There is no free plan. Pricing, the free trial and how to cancel

Physiqo is coming soon to iPhone. Join the waitlist and you'll get one email the day it's on the App Store.

Last updated: 31 October 2026