The health star rating system ranks food products on a scale from half a star (least healthy) to five stars (most healthy), allowing you to make healthier choices at a glance.
The rating is based on an algorithm which firstly takes into account kilojoules plus three 'negative' ('bad') nutrients – saturated fat, sodium and total sugars.
These four aspects of a food – kilojoules, saturated fat, sodium and sugars – are the basis for the rating because they're associated with increasing the risk factors for chronic diseases like type 2 diabetes, heart disease and obesity.
This is balanced against the 'positive' aspects of a food – its fruit, vegetable, nuts or legumes content (all valuable sources of a range of vitamins, minerals and antioxidants), as well as the protein and dietary fibre content in some cases.
The data used for calculations is per 100g or 100mL of a food.