Understanding calories

NHS

The amount of energy in an item of food or drink is measured in calories.

When we eat and drink more calories than we use up, our bodies store the excess as body fat. If this continues over time we may put on weight.

As a guide, an average man needs around 2,500kcal (10,500kJ) a day to maintain a healthy body weight.

For an average woman, that figure is around 2,000kcal (8,400kJ) a day.

These values can vary depending on age, size and levels of physical activity, among other factors.

You can check whether you're a healthy weight by using the BMI Healthy Weight Calculator.

Calories and energy balance

Our bodies need energy to keep us alive and our organs functioning normally. When we eat and drink, we put energy into our bodies.

Our bodies use up that energy through everyday movement, which includes everything from breathing to running.

To maintain a stable weight, the energy we put into our bodies must be the same as the energy we use by normal bodily functions and physical activity.

An important part of a healthy diet is balancing the energy you put into your bodies with the energy you use.

For example, the more physical activity we do the more energy we use.

If you consume too much energy on one day, don't worry; just try to take in less energy on the following days.

Checking calories in food

Knowing the calorie content of food and drink can help ensure you're not consuming too much.

The calorie content of many shop-bought foods is stated on the packaging as part of the nutrition label.

This information will appear under the "Energy" heading. The calorie content is often given in kcals, which is short for "kilocalories", and also in kJ, which is short for "kilojoules".

A "kilocalorie" is another word for what is commonly called a "calorie", so 1,000 calories will be written as 1,000kcals.

Kilojoules are the metric measurement of calories. To find the energy content in kilojoules, multiply the calorie figure by 4.2.

The label will usually tell you how many calories are contained in 100 grams or 100 millilitres of the food or drink, so you can compare the calorie content of different products.

Many labels will also state the number of calories in "one portion" of the food. But remember that the manufacturer's idea of "one portion" may not be the same as yours, so there could be more calories in the portion you serve yourself.

You can use the calorie information to assess how a particular food fits into your daily calorie intake.

Calorie counters

There is a wide range of online calorie counters for computers and mobile phones. Many of these can be downloaded and used for free.

NHS Choices can't verify their data but they can be helpful to track your calories by recording all of the food you eat in a day.

Some restaurants put calorie information on their menus, so you can also check the calorie content of foods when eating out. Calories should be given per portion or per meal.

Burning calories

The amount of calories people use by doing a certain physical activity varies, depending on a range of factors, including size and age.

The more vigorously you do an activity, the more calories you will use. For example, fast walking will burn more calories than walking at a moderate pace.

If you're gaining weight, it could mean you've been regularly eating and drinking more calories than you've been using.

To lose weight, you need to use more energy than you consume, and continue this over a period of time.

The best approach is to combine diet changes with increased physical activity.

Useful resources

To avail of EA staff discounts for Council Leisure Centres: 1. Select a Leisure Centre...
Fun, fast food for less. This is a practical six-week nutrition programme aimed at...
The message boards are here to support you whether you are concerned about yourself or...
Cancer Focus NI, Keeping Well vans are mobile drop-in units which bring health checks,...
Kingfisher groups are a confidential, inclusive and welcoming space for anyone suffering...
Solace is a free video-based peer support group hosted over Zoom. It’s for anyone...
You can talk one-to-one with us using our secure instant messaging service. Beat’s...
Cancer Focus NI can provide a wide range of presentations to meet the needs of your...
Raising Resilience is a series of online workshops for carers that take place live over...
The Quick Fit programme offers positive steps to improve your health through diet and...
Nightingale groups are confidential, inclusive, and welcoming spaces for anyone with...
Solace is a free video-based peer support group hosted over Zoom. It’s for anyone...
Swan groups are a confidential, inclusive and welcoming space for anyone with anorexia to...
This idea is a walk in the park. It really is that simple, post a news item to see how...
Our free Easy Meals app is a great way to eat foods that are healthier for you. You’ll...
Fitness tracker
Fitness tracker
The Nike+ Run Club app tracks your run and helps you reach your goals, whether it’s...
Active 10 is a free and easy to use walking app that tracks your walking and shows you...
Fabulous! Is a motivational app that uses challenges to help build physically and...
Nutrition scanner
Develop healthier eating habits, be more active, and get on track to start losing weight...
It’s an easy to follow programme known the world over, and perfect for those new to...
Food diary, exercise tracker and diet coach
Find out if you're a healthy weight
The plan is designed to help you lose weight at a safe rate of 0.5kg to 1kg (1lb to 2lb) each week by sticking to a daily calorie allowance. For most men, this means sticking to a calorie limit of no more than 1,900kcal a day, and 1,400kcal for most women. The weight loss plan is broken down into 12 weeks. It is full of healthy eating, diet and physical activity advice, including weekly challenges. Each week contains a food and activity chart to help you record your calories, exercise and weight loss so you can see how well you're doing at a glance. If you're using the downloadable PDFs, print the chart out at the start of your week. Stick it somewhere you can see it, such as the fridge or a kitchen cupboard, and update it at the end of each day.