What are calories?
A calorie is a unit of energy. The word calorie is short for kilocalorie (kcal), which is why you’ll see calories displayed as ‘kcal’ on food packaging. You might notice kilojoules (kJ) shown on packaging too. Kilojoules are simply the metric units of calories.
1 calorie (kcal) = 4.2 kilojoules (kJ)
How many calories should you eat a day?
The number of calories your body needs every day can differ depending on things like your age, gender, size, the temperature and how active you are. But in general, the average man needs around 2,500 calories a day, while the average woman needs around 2,000 calories a day to maintain a steady weight. If you want to lose weight, you’ll need to create a calorie deficit in your body. You do this either by eating less, exercising more, or a combination of the two. If you want to gain weight, you’ll need to take in more calories than you’re using.
What foods are high in calories?
Fat contains more than twice as many calories per gram than carbohydrates and protein. But it’s important to remember there are different types of fat. Saturated fats can be harmful to your health and you should try to eat less of these. Saturated fats are found in red meat, full fat dairy products like butter and cheese, and cakes, biscuits and pastries.
Unsaturated fats on the other hand can help to keep your heart healthy. Good examples of unsaturated fats include oily fish like mackerel and salmon, unsalted nuts, seeds and avocado.
Although these good, unsaturated fats can be high in calories too, they’re also an important part of a balanced diet. So if you’re trying to keep an eye on how many calories you’re eating, don’t cut out fats altogether. Instead, choose healthy, unsaturated fats where possible and monitor your portion sizes of these.
Alcohol is also high in calories, with almost as many calories per gram as fat and very little nutritional value.
- Fat: 9 calories per gram.
- Protein: 4 calories per gram.
- Carbohydrates: 3.75 calories per gram.
- Alcohol: 7 calories per gram.
How to find calories on food labels
Calories and kilojoules are displayed on the back of food labels. They’re shown as kcal and kJ per 100g/ml or per portion of the product. If you’re looking at the nutritional value per portion of the product, take a look at the weight of the product too. For example, the nutritional label on your yoghurt might say there’s 100 calories per 120 gram portion and the tub is actually 150 grams in weight. So make sure to check and adjust the calories if you need to.
You can also use the traffic light labelling shown on the front of some food packaging to get a quick overview of whether a product is high in calories or not. Traffic light labels show the calories, sugar, fat, saturated fat and salt content of the food and categorise these into either green, amber or red depending on their nutritional value. So opt for as many green labels as possible.
Heres what approximately* 100 calories of some common foods looks like:
(Roughly 300 grams)
(About two large squares)
(About 250g–300g raw)
(Roughly one level tablespoon)
(One small 125ml glass)
(Roughly 250 grams)
Unsalted cashew nuts
(About half a handful, or roughly 15 grams)
(One medium sized banana)
Plain digestive biscuits
(One and a half biscuits)
(One 250ml glass)
(Roughly five level teaspoons)
(About 250g raw)
(One large handful – or just over 30g)
(About 20g – less than one packet)
*Portion sizes may vary slightly from those shown dependant on product and brand.
Are you interested in learning more about your health? Discover more about our range of health assessments.