- Compare products per 100 g. Portion sizes vary and are often smaller than what people eat.
- Traffic lights show fat, saturates, sugars and salt as low, medium or high.
- Reference intakes are for an average adult, not a training target. Protein at 50 g is too low for lifters.
- Ingredients are listed by weight, heaviest first. Allergens are highlighted.
- 'High protein' and 'high fibre' have legal definitions. 'Natural' and 'clean' do not.
Front of pack: the traffic lights
Many UK products use a front-of-pack label with red, amber and green colours for fat, saturated fat, sugars and salt, plus the energy content. It is voluntary, so not every product has it, but most supermarkets use it on their own-brand ranges.
The colours are based on the amount per 100 g of food. For foods, the thresholds are:
- Fat: green 3 g or less, red more than 17.5 g
- Saturates: green 1.5 g or less, red more than 5 g
- Sugars: green 5 g or less, red more than 22.5 g
- Salt: green 0.3 g or less, red more than 1.5 g
Anything in between is amber. Drinks have lower thresholds per 100 ml, and a large portion can also push a nutrient into red. As a rule of thumb, more greens is better, ambers are fine most of the time and reds are best as occasional choices.
Traffic lights have limits. Nuts, olive oil and oily fish often show red or amber for fat, but they are healthy foods. And the labels say nothing about protein or fibre. Use them to compare similar products, not to judge a food in isolation.
Back of pack: the nutrition panel
The nutrition table on the back gives the full picture. It always shows values per 100 g or 100 ml, and often per portion too.
- Energy: in kJ and kcal. Kcal is what most people mean by calories.
- Fat, of which saturates: total fat and how much of it is saturated.
- Carbohydrate, of which sugars: total carbohydrate and how much is sugar. This includes natural sugars from milk and fruit, not just added sugar.
- Fibre: not always shown, but useful when it is.
- Protein: the number people who train usually care about most.
- Salt: in grams. Adults should have no more than 6 g a day.
Reference intakes are not your targets
Many labels show a percentage of the reference intake, often written as RI. These are based on an average adult eating 2,000 kcal a day:
- Energy: 2,000 kcal
- Fat: 70 g, of which saturates 20 g
- Carbohydrate: 260 g, of which sugars 90 g
- Protein: 50 g
- Salt: 6 g
They are a useful yardstick, but they are not personal targets. A 90 kg man training five times a week needs far more energy than 2,000 kcal, and anyone who lifts needs much more protein than 50 g. See how much protein you need for a figure based on your body weight.
The sugars figure of 90 g is total sugars, including those in milk and fruit. The limit for free sugars is much lower at 30 g a day, as explained in our guide to sugar.
The ingredients list
Ingredients are listed in order of weight, from most to least. If sugar, or one of its many names, appears in the first two or three items, the product is likely to be high in it. Some ingredients also show a percentage, such as 'chicken (32%)', which is useful when comparing ready meals and sausages.
By law, the 14 major allergens, including milk, eggs, peanuts, tree nuts, gluten-containing cereals, soya, fish and sesame, must be highlighted in the ingredients list, usually in bold. Food made and pre-packed on the premises where it is sold must now carry a full ingredients list with allergens highlighted too.
A long list of unfamiliar ingredients often signals a highly processed product. That is not automatically bad, but it is worth knowing. Our guide to ultra-processed food explains why.
What claims actually mean
Nutrition claims on packs have legal definitions in the UK. Here are the ones people who train see most:
- 'Source of protein': at least 12% of the product's energy comes from protein.
- 'High protein': at least 20% of the product's energy comes from protein.
- 'Source of fibre': at least 3 g of fibre per 100 g.
- 'High fibre': at least 6 g of fibre per 100 g.
- 'Low fat': no more than 3 g of fat per 100 g for food.
- 'Low sugar': no more than 5 g of sugar per 100 g for food.
- 'Reduced' or 'light': at least 30% less of that nutrient than a similar standard product. It may still be high.
Terms like 'natural', 'clean', 'guilt-free' and 'wholesome' have no nutritional definition. A 'high protein' cookie can still be high in sugar and calories. Always turn the pack over.
Dates, and a 30 second routine
'Use by' dates are about safety. Do not eat food after its use by date, even if it looks and smells fine. 'Best before' dates are about quality, so food is usually safe to eat afterwards, though it may not be at its best. Freezing food before its use by date stops the clock.
When you are comparing two products in the shop, this routine takes about 30 seconds:
- Turn the pack over and find the per 100 g column.
- Check calories, protein and fibre, depending on your goal.
- Check saturates, sugars and salt against the traffic light thresholds.
- Glance at the first three ingredients.
- Choose the one that fits your goals better, then stop overthinking it.
Once you have done this for the products you buy every week, you rarely need to do it again. If you are tracking food for fat loss, the per 100 g figures also make weighing much easier, as explained in tracking calories without obsessing. If you would like help building better shopping habits alongside your training, nutrition and accountability coaching is one of the services at Lycan Strength.
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Questions
Should I look at per 100 g or per portion?
Use per 100 g to compare products fairly. Use per portion only if you actually eat that portion, which is worth checking with scales once or twice.
What does RI mean on food labels?
RI stands for reference intake, the amount of energy and nutrients an average adult needs in a day. It is a guide, not a personal target.
Is a red traffic light always bad?
No. Nuts, cheese and oily fish often show red for fat but are nutritious foods. Traffic lights are best used to compare similar products.
General guidance for healthy adults. If you have a medical condition, injury or are pregnant, check with a health professional before changing your training or diet.
