What's really in your food? How to read a food label properly

The front of a food packet is marketing. The back is information. Most shoppers spend most of their time looking at the front - and food companies know it.

Understanding how to read a food label properly - particularly the ingredient list and the nutritional panel - is one of the most practical things you can do to make better choices at the supermarket. This guide breaks it all down.

The ingredient list: the most important part of any label

The ingredient list tells you exactly what is in a product. By law in the UK, Australia, and New Zealand, ingredients must be listed in descending order of weight - from the largest ingredient to the smallest. This means the first ingredient makes up the largest proportion of the product, and the last ingredient is present in the smallest amount.

What to look for first

The first three ingredients are the most important. They collectively make up the majority of the product. If the first ingredient is sugar, refined flour, or a fat, that product is primarily made of that ingredient - regardless of what the front of the pack says.

The short ingredient list rule

Minimally processed, whole foods generally have short ingredient lists. A tin of chickpeas might say: chickpeas, water, salt. A packet of almonds: almonds. When ingredient lists run to twenty or more items - particularly when many of those items are additives, emulsifiers, and flavour enhancers - it is a sign of a heavily processed product.

How to spot hidden sugar

Sugar appears under more than 60 different names on ingredient lists. Food manufacturers sometimes use several different types of sugar in a single product - which keeps each individual sugar lower on the ingredients list, even though the combined sugar content is significant.

Common sugar aliases to watch for: glucose, fructose, dextrose, maltose, sucrose, high fructose corn syrup, corn syrup, rice syrup, agave, agave nectar, evaporated cane juice, molasses, treacle, malt, malt extract, invert sugar, golden syrup, coconut sugar, fruit juice concentrate, maltodextrin.

The nutritional information panel

The nutritional panel shows you the quantity of key nutrients in the product - typically per 100g and per serving. The "per 100g" column is the most useful because it allows you to compare different products fairly, regardless of serving size differences.

Key values to check

• Sugars (per 100g): Under 5g is low, 5–15g is moderate, over 15g is high
• Saturated fat (per 100g): Under 1.5g is low, 1.5–5g is moderate, over 5g is high
• Salt/Sodium (per 100g): Under 0.3g salt is low, 0.3–1.5g is moderate, over 1.5g is high
• Fibre (per 100g): Over 6g is high, 3–6g is a source of fibre, under 3g is low
• Protein (per 100g): Context-dependent, but higher is generally better for satiety

UK traffic light labelling

Many products in the UK display a traffic light system on the front of pack - green, amber, or red - for fat, saturated fat, sugars, and salt. This is based on the UK Food Standards Agency reference intakes:

SustiScan's Health Indicator circles use these same UK FSA thresholds - so the colours you see in the app match the same standard you see on products in UK supermarkets.

Watch out for serving size manipulation

The "per serving" column is where labels can mislead. A manufacturer might define a serving as an unrealistically small amount - for example, a 30g serving of a product you realistically eat 80–100g of at a time. Always use the per 100g column to compare products, and then calculate realistically how much you will actually consume.

Front-of-pack health claims - what they actually mean

Understanding front-of-pack rating systems

Nutri-Score (UK, Europe)

Nutri-Score grades products from A (dark green, best) to E (red, worst) based on a nutritional algorithm considering beneficial nutrients (fibre, protein, fruit/vegetables) and less beneficial ones (saturated fat, sugar, sodium) per 100g. Widely used in France, Germany, and increasingly across Europe. Recognised by the UK Food Standards Agency.

Health Star Rating (Australia and New Zealand)

A voluntary front-of-pack labelling system used in Australia and NZ that rates products from 0.5 to 5 stars. Products with more stars are generally healthier choices within their category. Note that Health Star Ratings compare products within categories - a 5-star soft drink is not the same as a 5-star vegetable.

A faster way to check what is actually in your food

Reading every label on every product during a weekly shop is genuinely time-consuming. SustiScan was built to make this practical - scan a barcode and get an instant breakdown of everything in a product: ingredient flags, health score, nutritional analysis, and additive classification - all in the time it would take you to locate the ingredient list in small print on the back of a packet.