There are guidelines to tell you if a food is high in fat, saturated fat, salt, sugar or not.
High: more than 17.5g of fat per 100g
Low: 3g of fat or less per 100g
High: more than 5g of saturated fat per 100g
Low: 1.5g of saturated fat or less per 100g
High: more than 22.5g of total sugars per 100g
Low: 5g of total sugars or less per 100g
High: more than 1.5g of salt per 100g (or 0.6g sodium)
Low: 0.3g of salt or less per 100g (or 0.1g sodium)
For example, if you're trying to cut down on saturated fat, eat fewer foods that have more than 5g of saturated fat per 100g.
Some nutrition labels on the back or side of packaging also provide information about reference intakes.
Most of the big supermarkets and many food manufacturers also display nutritional information on the front of pre-packed food.
This is very useful when you want to compare different food products at a glance.
Front-of-pack labels usually give a quick guide to:
These labels provide information on the number of grams of fat, saturated fat, sugars and salt, and the amount of energy (in kJ and kcal) in a serving or portion of the food.
But be aware that the manufacturer's idea of a portion may be different from yours.
Some front-of-pack nutrition labels also provide information about reference intakes.
Nutrition labels can also provide information on how a particular food or drink product fits into your daily recommended diet.
Reference intakes are guidelines about the approximate amount of particular nutrients and energy required for a healthy diet.
Some front-of-pack nutrition labels use red, amber and green colour coding.
Colour-coded nutritional information tells you at a glance if the food has high, medium or low amounts of fat, saturated fat, sugars and salt:
In short, the more green on the label, the healthier the choice. If you buy a food that has all or mostly green on the label, you know straight away that it's a healthier choice.
Amber means neither high nor low, so you can eat foods with all or mostly amber on the label most of the time.
But any red on the label means the food is high in fat, saturated fat, salt or sugars, and these are the foods we should cut down on.
Try to eat these foods less often and in small amounts.
Most pre-packed food products also have a list of ingredients on the packaging or an attached label.
The ingredients list can also help you work out how healthy the product is.
Ingredients are listed in order of weight, so the main ingredients in the packaged food always come first.
That means that if the first few ingredients are high-fat ingredients, such as cream, butter or oil, then the food in question is a high-fat food.
You're standing in the supermarket aisle looking at two similar products, trying to decide which to choose. You want to make the healthier choice, but you're in a hurry.
If you're buying ready meals, check to see if there's a nutrition label on the front of the pack, and then see how your choices stack up when it comes to the amount of energy, fat, saturated fat, sugars and salt.
If the nutrition labels use colour coding, you'll often find a mixture of red, amber and green.
So when you're choosing between similar products, try to go for more greens and ambers, and fewer reds, if you want to make a healthier choice.
But remember, even healthier ready meals may be higher in fat and energy than the homemade equivalent.
And if you make the meal yourself, you could also save money.