The Importance of Reading Food Labels
Every week, patients tell me they are trying to eat better. I ask what they check on a food label. Fat content. Calories. Everything else gets a pass. The label is there, and most people are not sure what to do with it.
UK food labelling law requires manufacturers to display accurate nutritional information, allergens, and ingredients on the pack. Marketing claims on the front, whether it is ‘100% natural’, ‘high protein’, or ‘low fat’, are not held to the same standard. Knowing how to read the back of the pack matters more.
The Building Blocks of a Food Label
Ingredients List
This is where you find out what the food is made of. The Food Standards Agency requires ingredients to be listed in descending order of weight, so the first ingredient makes up the biggest share of the product.
A scan of the top three ingredients tells you a lot. Whole foods near the top, fruit, oats, chicken, olive oil, are a good sign. Sugar, salt, glucose syrup, or hydrogenated fat near the top is a red flag. A long ingredients list is not a problem on its own, but if most of what is listed are not recognisable foods, that is worth pausing on.
Serving Size
Every number on the label relates to one serving, and the manufacturer sets what that serving is. A sharing bag of crisps might list values for a 25g portion, when most people eat 50g or more in one sitting. Check the serving size before comparing products or calculating your intake.
The more useful column, on most UK labels, is ‘per 100g’. This lets you compare products on equal terms, because you are looking at the same quantity regardless of how the manufacturer has defined a portion. Two products with different serving sizes become comparable per 100g.
Calorie Content
Calories measure the energy in food. Are all calories equal? No. 100 calories from oats and 100 calories from a biscuit have different effects on satiety, blood sugar, and hunger an hour later. The calorie count is a useful indicator, but the nutritional context matters as much.
Most UK labels now include a Reference Intake (RI) percentage alongside each nutrient. This shows what proportion of the recommended daily amount a single serving provides. An RI% under 5 means the food is low in that nutrient; over 20 means it is high. Use these as rough benchmarks rather than precise targets, but they are a fast way to compare products at a glance.
Macronutrients
Carbohydrates, proteins, and fats are the three macronutrients that provide energy. Getting a reasonable balance across the day matters, but the source matters more than the ratio. Complex carbs from whole grains, legumes, and vegetables have a different effect on blood sugar to refined carbs from white bread and sugary drinks. Unsaturated fats from olive oil, nuts, and oily fish differ from the saturated fats in processed meat and pastry. Aim for variety from whole food sources, and the ratios tend to take care of themselves.
Sugar Content
Added sugars appear under many names: glucose syrup, dextrose, fructose, maltose, evaporated cane juice. The figure listed as ‘of which sugars’ covers both the sugars in fruit and dairy, and added sugars. The ingredients list is the more useful check, because it shows how many sugar synonyms are present and how high up the list they appear.
The NHS recommends adults consume no more than 30 grams of free sugars per day. That number sounds manageable until I mention to patients that a single 330ml can of fizzy drink can contain around 35 grams. Over the limit in one drink. A medium apple contains about 11 grams of sugar, for comparison.
Sodium (Salt) Content
Most adults in the UK eat more salt than the recommended 6 grams per day, with the excess coming from processed foods, bread, and ready meals rather than the salt shaker. If you have high blood pressure, or a family history of it, checking salt content on labels is a practical step worth taking.
UK labels show both sodium and salt content. Salt is sodium multiplied by 2.5. A RI% of 20 or above for salt means the food is high in salt. Less than 1.5g of salt per 100g is a reasonable guide to a low-salt product, and keeping your daily total below 6g is the NHS target.
Fibre Content
Fibre supports gut health and helps with satiety. Most adults in the UK eat around 18 grams a day, below the recommended 30 grams. Foods with 3 grams or more of fibre per 100g are a good source. Look for whole grains, pulses, and vegetables in the ingredients list, not the fibre figure in isolation.
Step by Step Guide to Reading Food Labels
Many products on UK supermarket shelves carry a traffic light on the front of the pack, colour-coded for fat, saturated fat, sugar, and salt. Green means the nutrient is at a low level per 100g; amber means medium; red means high. A green-heavy result is a strong choice. Lots of red is a signal to eat it less often, or in smaller amounts.
For a practical read: check the serving size first, then scan the traffic light or RI% figures for salt and sugar (the two most people underestimate), then look at the first three ingredients. That is a 30-second check covering most of what you need to know before the item goes in the basket.
Common Traps to Avoid When Reading Food Labels
A common mistake is focusing on one nutrient while ignoring the others. A ‘low fat’ product can be high in sugar; a ‘high protein’ one can be high in salt. Front-of-pack labels like ‘natural’, ‘wholesome’, or ‘made with real fruit’ are marketing terms, not regulated nutritional claims. Check the back regardless.
Portion sizes catch people out. A bag of crisps listed as two servings gets eaten as one, which means you need to double the calorie and sugar figures. Measure out a single serving, at least once, to see what the label is describing.
A few other traps worth knowing:
- Front-of-pack health claims: phrases like ‘made with whole grains’ or ‘contains real fruit’ may refer to a small fraction of the product. Check where these ingredients sit in the list.
- Missing fibre and protein: most people check fat, sugar, and calories, then stop. Fibre affects satiety and gut health; protein affects fullness and muscle maintenance. Both are on the label.
- Skipping the ingredients list: reasonable RI% figures do not guarantee a good product. Two items can have identical nutritional panels and very different ingredients. Check both.
Making Sense of the Label
No food is perfect, and reading labels is not about finding the perfect product. A varied diet based on whole foods will be nutritious regardless of whether you have scrutinised every RI% figure. Labels are most useful for comparing similar products, spotting hidden salt and sugar, and seeing through front-of-pack claims.
The next time you are at the supermarket, give a label 30 seconds before it goes in the basket. Check the serving size, scan the traffic lights, read the first three ingredients. Eating well does not require becoming a nutritionist. Knowing where to look is enough.
