How to Read Nutrition Labels Like a Dietitian

Learning to read nutrition labels like a dietitian takes about five minutes once you know what to look for. Most people scan the calories, glance at the traffic light colours (red, amber, green), and move on. But the real story is in the details — hidden sugars, serving size sleight-of-hand, and marketing claims that sound health-conscious but aren't. This guide walks you through each section of a nutrition label so you can compare products, spot the tricks, and make choices that actually match your goals.

Why Nutrition Labels Exist (And Why Food Companies Make Them Hard to Read)

Food labeling is mandatory in the UK — manufacturers must show calories, fat, saturated fat, carbohydrates, sugars, protein, and salt per serving. The law exists because decades of research showed people can't guess the nutritional content of food. A muffin looks smaller than a burger, so you'd guess it's healthier. Spoiler: it often isn't.

But here's the trick: companies choose the serving size. A 200g chocolate bar might be labeled as "four servings" so each serving looks less bad. The "serving size" on the label is not the serving size you'd actually eat — it's the serving size that made their marketing numbers look best. That's why the first thing a dietitian does is check the serving size and multiply the other numbers by how much you'd actually eat.

Example: A 500ml bottle of "low-sugar" juice claims 5g sugar per serving. Looks good. But if the serving size is 200ml and you drink the whole bottle, you're actually getting 12.5g sugar. Always check: "servings per package" × "serving size" = your likely intake.

The Five Numbers That Actually Matter

Most UK labels use the traffic light system as a quick visual guide, plus a percentage of the reference intake. Here's how to read each one:

1. Calories

This is straightforward: it's the energy content of one serving, measured in kilocalories (kcal). Your daily target depends on age, sex, activity level, and goals. How your age affects calorie needs matters more as you get older, and alcohol affects your calorie intake more than most people realise. If you want a personal target, work out your TDEE (total daily energy expenditure) — that's the single most useful number for weight management.

2. Serving Size (and Servings Per Package)

Check this first, every time. A 300g pack might be "2 servings" (so 150g per serving) or "4 servings" (75g per serving). Every number on the label applies to whichever serving is listed. If you eat the whole pack and it says "2 servings," you need to double every figure.

3. Sugars (and "Added Sugars" if shown separately)

The label shows total sugars first, then (on newer labels) added sugars separately. The distinction matters:

• Natural sugars come from fruit, milk, or whole foods — your body processes these differently because they come with fibre, protein, or fat that slows absorption.
• Added sugars are sugar added during manufacturing — a biscuit or yogurt might list 15g sugar per serving, most or all of which is added.

The NHS recommends no more than 30g of free sugars per day for adults. That includes honey, syrups, and fruit juice (not whole fruit). If a single serving of breakfast cereal has 12g added sugar, you've used up 40% of your daily budget in one bowl.

4. Fat (Total, Saturated, Trans)

Fat isn't the enemy — but saturated fat in excess is linked to cardiovascular risk. The label breaks it down:

• Total fat — all fat in the product
• Saturated fat — the kind you want to limit
• Trans fat — artificial fats; avoid these completely

Saturated fat should be no more than 30g per day for women, 35g for men. That 100g pack of biscuits with 8g saturated fat per serving (2 servings per pack) contributes 16g — more than half your daily limit in a snack. For muscle building or general health goals, remember that protein from food also matters for satiety. Read more about how macros affect your diet.

5. Sodium

The NHS recommends no more than 6g salt per day (about 2,400mg sodium). Ready meals, sauces, bread, and breakfast cereals are often the hidden culprits. A single tin of soup can contain 40% of your daily salt allowance. The label shows sodium in milligrams — remember 1g salt equals 400mg sodium, so divide by 400 if that helps.

The Ingredients List Is Where the Real Information Hides

The label on the front of the pack is marketing. The ingredients list on the back is the truth.

Ingredients are listed by weight, so the first three make up the bulk of the product. A breakfast cereal that lists "wheat flour, sugar, honey" has a lot of sugar. One that lists "oats, whole wheat, flax seed" is a different product even if the calories look similar — because the fibre content is different, and fibre changes how your body processes the food.

Watch out for:

• Multiple types of sugar — if sugar appears three times in the first five ingredients under different names (glucose, honey, dextrose), the product is much higher in sugar than it looks.
• Hydrogenated oils — avoid these. Mostly banned now, but check anyway.
• Long lists of additives — more E numbers don't necessarily mean bad, but simpler foods tend to be nutritionally simpler too.

Marketing claims on the front ("high in fibre," "no added sugar," "natural") don't have to match the ingredients list. "No added sugar" doesn't mean low-sugar — a drink with only fruit juice is labeled "no added sugar" but can have 20g of natural sugars per serving. "Natural" has no legal definition.

How to Compare Two Products (The Dietitian's Method)

You're standing in the supermarket with two cereals, two yogurts, or two protein bars. Here's how to compare them fairly:

1. Check the serving size first. If one is 40g and one is 50g, you can't compare them directly.
2. Compare sugar content per 100g, not per serving. This removes the serving-size trick. Divide grams of sugar by serving size in grams, multiply by 100.
3. Check the ingredient list. Does one list whole grains or fruit first? Does one have added sugar?
4. Calculate satiety. If Product A has 200 calories and 15g protein, it'll keep you fuller longer than Product B with 200 calories and 5g protein. Protein, fibre, and fat increase satiety; sugar and refined carbs don't.

Example: Comparing two breakfast cereals.

• Cereal A: 200 calories, 7g sugar, 2g fibre, first ingredient is whole wheat
• Cereal B: 180 calories, 12g sugar, 1g fibre, first ingredient is refined wheat

Cereal B looks lower-calorie, but Cereal A will keep you full longer (more fibre, less sugar). Over a week, Cereal A might help you eat fewer total calories, even though one serving has more.

Common Label Tricks and How to Spot Them

Food companies spend millions on labeling design. Here are the tricks most of them use:

1. Tiny serving sizes — A chocolate bar might be labeled as "1.5 servings." Nobody eats exactly 1.5 biscuits.
2. Highlighting good numbers, hiding bad ones — Large, colourful calorie count on the front; small-print sugar on the back.
3. Using "per 100g" when it helps them — Some labels show "per serving" when the serving is tiny, and "per 100g" when it looks better.
4. Front-of-pack marketing vs back-of-pack truth — A cereal claims "whole grain" in big letters, but the ingredient list shows refined wheat first.

The fix: always read the back of the pack, always check the serving size, always compare per-100g when comparing two products.

Frequently Asked Questions

How much sugar is too much? The NHS recommends 30g of free sugars per day (about 7 teaspoons). Added sugars, honey, syrups, and fruit juice all count. Whole fruit doesn't, because fibre slows absorption. If you're trying to lose weight, keeping under 15g added sugar per day makes a bigger difference than almost any other single change.

What's the difference between added sugars and natural sugars? Natural sugars come with fibre, fat, or protein that slows how fast your body absorbs them. A banana has 27g sugar but also 3g fibre, so it doesn't spike blood sugar the same way 27g of table sugar does. Added sugar in a drink hits your bloodstream fast. Check the label for "sugars" (total) and "of which sugars" (added, if shown).

Should I worry about fat? No — but saturated fat, yes. Fat is calorie-dense (9 calories per gram vs 4 for protein and carbs), so it adds up fast. But fat also increases satiety and is essential for hormones. A product with 10g fat from olive oil is different from 10g fat from trans fats. Check the label and ingredients.

What does "daily value %" mean? It's how much of the NHS/WHO recommended daily intake that serving provides. So if a yogurt says "calcium 20%," that serving gives you 20% of the 1,000mg calcium you're supposed to eat per day. Useful as a quick guide — you can even use our percentage calculator to work out exact amounts — but remember the percentages assume 2,000 calories per day. Your actual target might be higher or lower.

How do I tell if a product is actually high in fibre? Look for "3g or more per serving" as a reasonable threshold. A cereal with 3g fibre per 200-calorie serving is better than one with 1g, even if the latter looks lower-calorie. Fibre isn't a bad carb — your body doesn't digest it for energy, and it slows down the absorption of sugar and fat.

Is organic always healthier? No. An organic chocolate bar is still a chocolate bar. Organic means it's grown without synthetic pesticides, which is good for the environment and possibly good for you, but it doesn't change the calories, sugar, or fat. Read the label on an organic product the same way you'd read a conventional one — don't assume it's healthier just because the label looks nice.

What's the deal with "low-fat" or "diet" versions? Companies often remove fat and add sugar to keep the product tasting decent. A low-fat yogurt with 12g sugar per serving isn't automatically healthier than a full-fat yogurt with 6g sugar. Full-fat versions keep you fuller longer and often have less added sugar. Always compare side by side; don't trust the marketing term.

Are artificial sweeteners okay? Probably fine in moderation. They have zero calories and don't spike blood sugar, so they're better than sugar if you're trying to lose weight. But if you're drinking three diet sodas a day, you're spending money on something with no nutritional value. Water, tea, or coffee are better if you can manage it. The research is ongoing, but nothing in the artificial sweetener category is flagged as dangerous at normal intake levels.