Counting carbohydrates; why and how

At a bare minimum, low-carbohydrate diets are an excellent strategy for;

  • maintaining smooth energy levels throughout the day,

  • maintaining a healthy neuroregulation of appetite (managing cravings, avoiding irritability and ‘hangriness’),

  • remaining sensitive to insulin (the opposite of diabetes),

  • increasing overall nutrient intake, and

  • slowing the effects of ageing [1-5].

Also, mounting evidence – and many experts – now suggest that certain varieties of carbohydrates greatly influence the development of chronic, age-related and neurodegenerative diseases [1, 4-8].

If any of that were even half true, a lower-carbohydrate eating strategy is perhaps something you might be interested in.

And here’s an essential tool to help you implement one.


Potatoes – a case study

After ingestion, carbohydrates – excluding the fibrous type – are broken down first into glucose, then stored in the body in the form of glycogen [9-11].

So what is glycogen?

Human starch is a term I have heard before, and I like this way of thinking about it.

Potatoes are loaded with carbohydrates, but if you want to get more specific, we could also refer to some of the carbohydrates contained within as starches.

Starch is a synonym for sugar. A particular arrangement of sugar, but sugar nonetheless [12].

After being eaten by a human, the potato is broken down – and if not immediately used – it is stored in the body as glycogen, aka, human starch – a form which the human body can preserve, and later use, as energy.

Mark Sisson, from, tells a story of Tour de France cyclists who would carry with them a baked potato in order to sustain their energy levels. This was way back before the days of Gatorade and fast-absorbing energy gels [13].

I realise that a potato is not generally regarded as a high-sugar food. It’s carbohydrate, with very little sugar, someone might point out upon consultation of their nutrition label.

And they’d be half right. Let’s have a look at an example.

russet potato.jpg


According to the label, there is only 2.3g of ‘sugar’ in this potato.

But the body doesn’t care about the words we use. The body only cares about the type of energy contained within the foods you just ate.

In this case, your body is able to extract over 60g of carbohydrates from this potato, which will then readily turn straight into glucose (sugar) once eaten.

This will then cause an extremely rapid increase in blood sugar levels – almost as quick as pure glucose (sugar) itself [14].

If the energy from the potato is not immediately used as energy, it will be stored in the body as glycogen.

This is perhaps the best case scenario.

Worst-case scenario might be that there is no storage space left for the glycogen, so your body will convert it to fat and store it on your hips, or somewhere you probably want it least.

In this context, there is little difference between a donut and a freshly-baked potato.

Sure, they are not identical to a molecule, and you could argue whether or not one is ‘healthier’ than the other, and that they effect the microbiome in different ways.

But at the end of the day, 60g of carbohydrate is 60g of carbohydrate.

And that’s not a small amount of carbohydrates in anyone’s book.


Counting carbohydrates; example scenarios

So this brings us here;

As far as the body is concerned, there are pretty much only two types of carbohydrate; fibre, and ‘usable’ carbohydrate [5,9].

‘Usable’ carbohydrate refers to the effective amount of glucose (sugar) that your body will be able to extract from a given food item. Usable carbohydrates are sometimes referred to as ‘net’, ‘effective’ or ‘impact’ carbs.

I like the term ‘usable’ carbohydrates.

Taking this into account, we get this equation;

Usable Carbohydrates = Total Carbohydrates - Total Fibre.

Just remember to ignore the subsection that reads ‘sugar’ or ‘added sugar’, as it’s irrelevant. And don’t be fooled by the polyols – the sugar alcohols – they should also be counted in your carb totals as well, or simply avoided.

Scenario 1: food item has no fibre

We just look for the total amount of carbohydrates listed and we’re done.

white rice.jpg


One serving of this rice delivers almost 80g of straight up glucose.

Scenario 2: food item contains fibre

We subtract fibre from the total carbohydrate count to get usable carbohydrates.




Usable carbohydrates = 27.2 – 4.9, which equals 22.3.

So, while the seller of this product would perhaps like you to think there is only 1.8 g – less than half a teaspoon – of sugar in a serving of this product, to your (infinitely more intelligent) body, there is actually over a tablespoon (22.3g) of sugar to work with.

That’s 12 times more usable sugar that the label would have you think.


Relevant tangents; why we subtract fibre from the total, ‘natural sugars’ and resistant starch

Fibre is technically a carbohydrate, but behaves very differently from the carbs derived from a ripe banana, or a donut, for that matter.

Fibre is fermented by our gut bacteria into a form of fat called Short Chain Fatty Acid’s, which then feed the beneficial bacteria in the gut [9,16].

At this point – I expect someone may bring up the matter of resistant starch.

While an intriguing topic – resistant starches have a very similar effect to fibrous carbohydrates – they should be of little concern to the average person, because it’s probably not the majority of what you are eating [15].

Unless you’re running around eating raw potatoes and unripe, acid-green bananas…?

Didn’t think so.

And I know people who say that unprocessed sources of carbohydrates – sources of so-called ‘natural sugars’ in fruits and starchy vegetables – just cannot be bad for you.

There is indeed substantial difference between processed and unprocessed carbohydrates; most notably, the ways in which they interact with the microbiome [17, 18].

But you can’t sit around and eat bananas all day and be at your best.

The carbs are still usable to the body. And again, perhaps more importantly, your storage space for carbohydrates is finite.

So earn your carbs through the right types of exercise, or steer well clear of them most of the time.


Common sources of usable carbohydrates

Just like our potato, grains of any type that constitute bread, pasta, rice, and cereals are dense sources of carbohydrates.

Starchy vegetables, and fruits are next on the list of obvious sources.

Following on from there, the suffix ‘–ose’ can be a big clue.

Aldose, ketose, lactose, sucrose, fructose, and galactose are all words from the carbohydrate family.

And then there are the polyols, aka, the sugar alcohols; erythritol, isomalt, lactitol, maltitol, mannitol, sorbitol and xylitol.

You probably don’t have time to memorise them all, and that’s ok.

That’s why we can just learn to count carbs.


Summing up

Low carbohydrate diets are not a fix-all for everyone’s health problems.

And neither is counting carbohydrates.

It is simply a strategy that you may find useful, if your goal is to successfully implement a lower-carbohydrate diet, in order to potentially gain some of the above-listed benefits.

This method will work on most nutrition labels.

Give it a try and see how much sugar you are actually consuming.





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