Reading a nutrition label properly
Always read the per-100 g column, not per serving. Serving sizes are chosen by the manufacturer and are frequently smaller than anyone eats. Per 100 g is the only figure that lets you compare two products or check what a tracker told you.
Per 100 g versus per serving
Almost every labelling problem comes back to this distinction.
Per 100 g is legally required in the UK and EU and is standardised. It lets you compare a cereal against another cereal, or check whether a "high protein" claim means anything.
Per serving is whatever the manufacturer decided a serving is. A cereal serving might be 30 g, which is a small bowl. A pizza might be labelled per half. Crisps come in bags that say two servings.
The ten-second method. Look at per 100 g for protein and calories, check the stated serving weight, then multiply by what you actually eat. That is the whole skill.
US labels differ: serving sizes are more regulated and per-100 g is often absent, so you work from serving size and servings per container. The principle is the same — find the weight, then scale.
What each line means
| What it says | What it means | What to watch for |
|---|---|---|
| Per 100 g | Legally required in the EU and UK. The only comparable figure. | Use this to compare products, always. |
| Per serving | The manufacturer's chosen portion. | Frequently smaller than anyone eats. Check the gram weight. |
| Of which sugars | Total sugars, added and natural combined. | Fruit and dairy products look high for harmless reasons. |
| Of which saturates | Saturated fat within the total. | Relevant to heart health, not to weight. |
| Fibre | Optional on UK/EU labels. | Its absence does not mean zero. |
| Salt vs sodium | Salt = sodium × 2.5. | US labels use sodium; UK/EU use salt. |
| “Light” or “reduced” | 30% less of something than the standard version. | Reduced fat often means added sugar, and similar calories. |
| “No added sugar” | None added; naturally occurring sugars remain. | Fruit juice qualifies and is still calorie-dense. |
Two extra notes. In the UK and EU, the carbohydrate figure excludes fibre; in the US it includes it, which is the origin of "net carbs". And the calorie figure is calculated from the macronutrients rather than measured, so small inconsistencies are normal.
The ingredients list, which tells you more
Ingredients are listed in descending order by weight, which makes the list more informative than the front of the pack.
- The first three ingredients are most of the product. If sugar or a syrup is among them, that is what you are mostly eating.
- Sugar has many names. Sucrose, glucose-fructose syrup, dextrose, maltodextrin, invert sugar, fruit juice concentrate, honey, agave, molasses, rice syrup. Split across several names, each appears further down the list.
- "Wholegrain" must be the first ingredient to mean much. "Made with wholegrain" often means a small proportion.
- Percentages are given for named ingredients. A "chicken and mushroom pie" must state the chicken percentage, and it is often lower than expected.
- A long list is not inherently bad. Many entries are vitamins or harmless stabilisers. Length is a weak signal.
Front-of-pack claims, decoded
- "High protein" — in the EU/UK, at least 20% of energy from protein. A chocolate bar can qualify while still being mostly sugar and fat.
- "Source of protein" — 12% of energy. A low bar.
- "Low fat" — 3 g or less per 100 g. Often compensated with sugar.
- "Reduced sugar" — 30% less than the standard version, which may still be a lot.
- "No added sugar" — none added; natural sugars remain. Fruit juice qualifies.
- "Sugar-free" — under 0.5 g per 100 g.
- "Light" / "lite" — 30% less of some nutrient. Sometimes 30% less of something you did not care about.
- "Natural", "clean", "artisan", "wellness" — no legal meaning.
- Protein bars — check calories per gram of protein. Many are 200 kcal for 10 g of protein, which is a confectionery product with a claim on it.
Where the numbers are simply wrong
Labels have a legal tolerance, and it is wider than most people assume.
- Tolerances of roughly ±20% are permitted on many declared values. A 200 kcal bar may legitimately be 240.
- Whole foods vary naturally. A "medium" banana ranges considerably; cuts of meat differ in fat content by a lot.
- Raw versus cooked weights matter enormously. 100 g of raw chicken becomes about 75 g cooked with the same calories. Whether your entry says raw or cooked can distort protein by 30%.
- Cooking added fat is often forgotten. A tablespoon of oil is 120 kcal, and it is the single most commonly omitted entry in food logging.
- Restaurant figures are estimates, and typically understate — see eating out while tracking.
- Crowd-sourced database entries are frequently wrong. Prefer entries with a verified barcode, and check them against the pack.
None of this makes tracking useless. It makes tracking a consistent estimate rather than a measurement — which is all it needs to be, because you adjust based on your weight trend rather than on the arithmetic. See calories: how to estimate your maintenance.
Common questions
Should I weigh food raw or cooked?
Raw is more consistent, since cooking loss varies. Whichever you choose, match the database entry to it.
Are calorie counts on labels accurate?
Close enough, within a tolerance of roughly ±20%. Consistency matters more than precision.
What is the difference between salt and sodium?
Salt = sodium × 2.5. UK and EU labels use salt; US labels use sodium.
Do I need to count vegetables?
Leafy and non-starchy vegetables contribute little. Starchy ones — potato, sweetcorn, peas — count.
Is "high protein" on the front reliable?
It meets a legal threshold that is easy to clear. Check the grams per 100 g yourself.
Why does my tracker disagree with the packet?
Database entries are often user-submitted and wrong. Trust the packet and correct the entry.
Do fibre grams count as carbohydrate?
Not in the UK/EU labelling convention; yes in the US. See fibre and why lifters under-eat it.
The practical version
- Read per 100 g. Serving sizes are chosen by the manufacturer.
- Check the stated serving weight, then scale to what you actually eat.
- The ingredients list is ordered by weight and tells you more than the front of the pack.
- Front-of-pack claims meet low legal thresholds — verify the grams yourself.
- Labels carry roughly ±20% tolerance; raw versus cooked weight is a bigger error source.
- Cooking oil is the most commonly forgotten entry in any food log.
Key takeaways
- Per 100 g is the only comparable figure; per-serving sizes are set by the manufacturer.
- The ingredients list is ordered by weight and is more informative than front-of-pack claims.
- Sugar appears under many names, which pushes each one further down the list.
- "High protein" in the EU/UK means 20% of energy — a chocolate bar can qualify.
- Labels carry roughly plus or minus 20% tolerance, so tracking is a consistent estimate.
- Raw versus cooked weight and forgotten cooking oil cause larger errors than label tolerance.
Related reading
General information, not medical or individualised advice. Speak to a doctor before starting a new programme, especially if you have a medical condition, are pregnant, or are returning from injury. If you train with a coach, their guidance takes precedence.
Track it, or none of this applies
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