If you've spent any time in low-carb circles, you'll have heard the phrase "net carbs". It's one of the most talked-about ideas in keto, and one of the most misunderstood. Even better, most of the advice online is written for American labels, which work differently from the ones on British shelves.

Here's what it all means, and how to count with confidence.

What Are Net Carbs?

Net carbs are the carbohydrates your body is expected to digest and absorb. The idea is simple: some carbohydrates, such as fibre, pass through largely undigested, so they're subtracted from the total to give a more useful number.

The usual formula is:

Net carbs = total carbohydrates minus fibre (and, for some people, certain sugar alcohols)

It's a handy way to compare foods, but the maths depends entirely on how your label is written.

The UK Label Twist

Here's the part most people miss. In the UK and the EU, the "carbohydrate" figure on the back of a pack generally already excludes fibre. Fibre is listed separately, on its own line.

In the US, total carbohydrate includes fibre, so subtracting it is the right thing to do. On a UK label, doing the same thing counts the fibre twice and leaves you with a number that's lower than the real one.

So before you reach for the calculator, ask one question: is fibre already left out of this figure? On most British packaging, the answer is yes.

What About Sugar Alcohols?

Sweeteners such as erythritol are sugar alcohols, or polyols, and they're treated differently across labels. Some brands and countries include them in the carbohydrate figure, while others handle them separately. Many people on a low-carb diet choose to subtract them, but that's a personal decision, and it's worth checking how the label you're reading treats them.

If you're unsure, the ingredients list and the "of which polyols" line, where present, will help you see what's going on.

A Simple Way to Count

1. Find the carbohydrate figure on the nutrition table, and check whether it's per 100g or per serving.
2. Check the fibre line. On a UK label, it's usually already excluded, so there's normally no need to subtract it again.
3. Look for polyols. Decide whether you want to include them in your count, and stay consistent.
4. Scale to your portion. Work out the figure for the amount you'll actually eat.

Why Net Carbs Aren't the Whole Story

Net carbs are a useful tool, but they're not perfect.

1. Not All Fibre Behaves the Same Way

Different fibres are fermented and absorbed to different degrees, so the result is an estimate rather than an exact figure.

2. Individual Responses Vary

Two people can eat the same food and see different blood sugar responses. If you're managing a health condition, speak to your GP or dietitian rather than relying on a formula alone.

3. Whole Foods Beat Clever Maths

A meal built around vegetables, protein and healthy fats keeps counting simple. The more processed a product is, the more careful label-reading becomes.

Keep It Simple

You don't need a degree in nutrition to eat low-carb well. Pick one method for counting, stick with it, and choose foods with clear, honest labelling. That way, the numbers work for you rather than against you.

Want a hand building a plan that suits your goals? Book a consultation with our nutritionist, or explore our low-carb pantry essentials to get started.