How to Read a Nutrition Label Like a Pro (UK Guide)

Nutrition labels are supposed to help you make informed food choices. In practice, they’re designed to be just confusing enough that most people give up and throw the item in the trolley anyway.

“Per serving” vs “per 100g.” Traffic light colours that don’t mean what you think. “High in protein” labels on products that are 70% sugar. Health claims that technically aren’t lying but definitely aren’t telling the full truth.

Once you know how to read labels properly, though, they become the most powerful tool in your macro tracking toolkit. Here’s your complete guide.

UK Labels vs US Labels

If you’re reading this from the UK (or anywhere in Europe), you’re in luck. UK/EU nutrition labelling is more standardised and consumer-friendly than US labelling.

UK labels must include (per 100g and often per serving):

• Energy (kJ and kcal)
• Fat (and saturated fat)
• Carbohydrate (and sugars)
• Fibre
• Protein
• Salt

US labels show:

• Calories
• Total fat, saturated fat, trans fat
• Cholesterol, sodium
• Total carbohydrate, dietary fibre, sugars (and added sugars)
• Protein

The critical difference: UK labels always show values per 100g, which makes comparing products straightforward. US labels only show values per “serving,” and manufacturers get to define what a “serving” is (more on that problem shortly).

The Per-100g Trick: Your Most Powerful Tool

Forget the “per serving” column. Look at the per 100g column every time. This is the only way to compare products fairly.

Why? Because “per serving” is manipulated. A chocolate bar might list its serving as “half a bar” so the calorie count looks lower. A bag of crisps might define a serving as 25g when you know perfectly well you’re eating the entire 150g bag.

Per 100g levels the playing field. Here’s how to use it:

Quick Reference: Per 100g Benchmarks

High protein (good for macro tracking):

• 20g+ protein per 100g = excellent protein source
• 10 to 20g per 100g = good protein source
• Under 10g per 100g = not a meaningful protein source

Fat levels:

• Under 3g per 100g = low fat
• 3 to 17.5g per 100g = medium fat
• Over 17.5g per 100g = high fat

Sugar levels:

• Under 5g per 100g = low sugar
• 5 to 22.5g per 100g = medium sugar
• Over 22.5g per 100g = high sugar

Fibre:

• Over 6g per 100g = high fibre
• 3 to 6g per 100g = source of fibre

These benchmarks come from UK Food Standards Agency guidelines and are the basis for the traffic light system on front-of-pack labels.

The Traffic Light System Explained

UK products often display front-of-pack traffic lights:

• 🟢 Green: Low in that nutrient
• 🟡 Amber: Medium
• 🔴 Red: High

The catch: traffic lights are based on per-portion values, not per 100g. If a manufacturer uses a tiny portion size, they can keep the lights green even for junk food.

Traffic lights are a useful quick glance, but always check the per-100g figures on the back for the real picture.

Decoding “Health” Claims

Food marketing is designed to make you feel good about buying the product. Here’s what common claims actually mean:

“High in Protein”

Under EU regulations, a product can claim “high in protein” if protein accounts for at least 20% of its energy value. Sounds strict, but this allows products with 15g of sugar per serving to call themselves “high protein” as long as the protein percentage hits 20%.

What to check: Look at the actual protein per 100g AND the sugar content. A protein bar with 20g protein but 25g sugar is not a health food; it’s a candy bar with a whey protein supplement.

”Low Fat”

Must contain less than 3g of fat per 100g. But “low fat” products often compensate by adding sugar for flavour. A low-fat yoghurt might have 15g of sugar per pot. That’s nearly 4 teaspoons.

What to check: When fat goes down, check if sugar went up.

”No Added Sugar”

This means no sugar was added during manufacturing. It does NOT mean the product is low in sugar. Fruit juices, dried fruits, and honey-based products can be “no added sugar” while containing 30g+ of natural sugars per serving.

What to check: Look at total sugars on the label, not just the claim on the front.

”Light” or “Lite”

Must be at least 30% lower in a specified nutrient (usually fat or calories) than the standard version. But 30% less than “extremely high” can still be “quite high.”

What to check: Compare the “lite” version to a genuinely healthy option, not just to the original.

”Natural” / “Clean” / “Wholesome”

These terms have virtually no legal definition in food labelling. Any product can call itself “natural.” It’s pure marketing.

The Serving Size Trap

This is the most common way labels mislead you.

Example: A bottle of smoothie says “120 calories per serving.” Reasonable, right? But the bottle contains 2.5 servings. If you drink the whole thing (and you will), that’s 300 calories, mostly from sugar.

Example: A bag of “healthy” granola lists 45g as a serving (about 3 tablespoons). Nobody eats 3 tablespoons of granola. A realistic bowl is 80 to 100g, nearly doubling the listed calories.

The fix: Always calculate based on how much you’ll actually eat, not the listed serving size. If you eat 150g of cereal, multiply the per-100g values by 1.5.

What to Actually Look For (Macro Tracking Edition)

When you’re tracking macros, you only need to focus on a few things:

1. Protein Per 100g

This is your first check. Is this product actually contributing meaningful protein, or is it a carb/fat source masquerading as “high protein”?

• Greek yoghurt: ~10g protein per 100g ✅
• “Protein” cereal: ~12g per 100g but also 25g carbs and 15g sugar ⚠️
• Chicken breast: ~31g per 100g ✅✅

2. Total Calories Per 100g

Cross-reference with your planned portion. If a product is 450 calories per 100g and you eat 200g, that’s 900 calories from one food item.

3. Sugar Content

Sugar contributes to your carbohydrate total. High sugar foods aren’t “bad” by default, but they’re less satiating than complex carbohydrates. If a product has more sugar than protein per 100g, it’s probably not helping your goals.

4. Fibre

Fibre is the unsung hero. It fills you up, supports gut health, and slows digestion. Most people get less than half the recommended 30g per day. Choosing higher-fibre versions of bread, cereals, and pasta makes a real difference.

Practical Label Reading: Three Examples

Example 1: Comparing Two Yoghurts

	Brand A “Protein Yoghurt”	Brand B “Plain Greek Yoghurt”
Calories/100g	95	66
Protein/100g	10g	10g
Carbs/100g	8g	3.8g
of which sugars	7g	3.8g
Fat/100g	2.5g	0.7g
Price per 100g	55p	20p

Same protein. Brand B has fewer calories, less sugar, less fat, and costs less than half the price. The “protein” label on Brand A is marketing, not value.

Example 2: “Healthy” Granola Bar

Front of pack says: “High in fibre! Only 98 calories per bar!” Back of pack per 100g: 440 calories, 5g protein, 56g carbs (24g sugars), 22g fat.

The bar weighs 22g. Of course it’s “only 98 calories,” it’s tiny. Per 100g, it’s essentially a biscuit. The fibre claim is technically true (6g per 100g) but buried under sugar and fat.

Example 3: Supermarket Bread

White sliced: 1.3g fibre, 7.9g protein per 100g Wholemeal sliced: 5.1g fibre, 10.1g protein per 100g

Same calories, similar price. The wholemeal has nearly 4x the fibre and more protein. This is where label reading pays off; small switches that compound over time.

Using Labels with Your Macro Tracker

Once you know how to read labels, you can cross-check your tracking app’s estimates. Snap a photo of your meal with Chowdown and compare the AI’s estimate with the label data on your packaged ingredients. This helps you calibrate both the AI and your own portion estimation skills.

For home-cooked meals, check the labels on individual ingredients (chicken, rice, oil, sauces) and you’ll build an intuitive understanding of what your macros look like.

If you’re new to tracking, use our free macro calculator to set your targets first. Then use label reading and food scanning together to hit them consistently.

The Bottom Line

Nutrition labels are your best friend once you know how to read them. The rules are simple:

1. Always check per 100g, not per serving
2. Ignore front-of-pack marketing claims and flip to the back
3. Compare protein, sugar, and fibre to separate genuinely nutritious products from dressed-up junk food
4. Watch for the serving size trap: calculate based on what you actually eat

These skills compound over time. After a few weeks of conscious label reading, you’ll be able to glance at a product and know within seconds whether it fits your macro targets.

Track your food with Chowdown, read your labels, and make every choice an informed one. That’s the foundation of sustainable nutrition, no gimmicks required.