What does 100 calories look like?

Calories are a well-known measure of the amount of energy in food. Keeping track of the number of calories in our food helps us to balance the energy we put into our bodies with the energy we use every day, leading to a healthy weight.

Calories and kilocalories

The term calorie is a commonly used shorthand for ‘kilocalorie’. On food packets you will find this written as kcal. Kilojoules (kJ) are the metric measurement of calories, and you’ll see both kJ and kcal on nutrition labels – 4.2kJ is equivalent to approximately 1kcal.

Energy throughout the day

Within a healthy balanced diet, women need on average 8,400kJ a day (2,000kcal), while men need on average 10,500kJ a day (2,500kcal).

A rough guide as to how your energy requirement can be spread throughout the day is as follows:

• Breakfast: 20% (a fifth of your energy intake)
• Lunch: 30% (about a third of your energy intake)
• Evening meal: 30% (about a third of your energy intake)
• Drinks and snacks: 20% (a fifth of your energy intake)

As you can see, any drinks or snacks you have count towards your daily energy total. If you eat more for your breakfast, lunch or evening meal, you may need to drop a snack later in the day to stay on track.

Comparing energy values: a visual guide

This guide shows energy values for 10 different foods. This will help you to visualise what 100kcal (420kJ) looks like and manage the number of calories you consume.

This amount, 100kcal, represents just 5% of a woman’s daily reference intake (4% for men), but this quickly adds up when adding ingredients during cooking or when we reach for a snack. High-fat foods have more energy per bite, while foods containing water, such as vegetables, have less.

These are not suggestions for snacks. They simply show how quickly calories can add up in certain foods. Some of the photos also show household objects, such as a pack of cards, to help illustrate the portion size.

Calories in oil, mayonnaise and butter

Oil is pure fat, which is why you only get a little over one tablespoon of olive oil; one level tablespoon of mayonnaise and just under one tablespoon of butter (a thick spread of butter on your bread) for 420kJ / 100kcal each.