A lot of people get hung up with how many grams of carbohydrates they need per kg of body weight.

Thing is

You can only really metabolize 60g of carbohydrates per hour, however there are studies to show that if you mix and match carbohydrate sources such as glucose/maltodextrin and fructose then you can exceed that intake to 90g.

Now I’m not going to get into too much geeky detail here,

but here’s a great way of understanding WHY you don’t need to

cram in as much carbohydrate as you can when racing.

First things first. (Sorry I lied about the geeky bit)

You have carbohydrate transporters within your small intestine.

SGLT1 is the transporter for glucose but throw too much glucose at it (60g + per hour) and the transporter becomes saturated.

This can cause an accumulation of glucose in the GI tract

causing all sorts of gastric upsets which trust me, you don’t want.

That’s good to know because 60g per hour of glucose is your absorption rate LIMITER, you don’t need to take any more per hour.

It’s important to point out here that although Maltodextrin (10 – 20 chains of glucose molecules) has a fast rate of absorption NO carbohydrate in isolation can be oxidized for energy above 60g. Carbohydrates taken above that and IMPORTANTLY in isolation and or high does can cause GI issues.

So can you increase the energy intake from carbohydrates per hour without causing GI distress.

Well yes you can, by combining the carbohydrate source such as glucose/Maltodextrins and fructose.


You also have a transporter for Fructose within the GI tract called GLUT5. It also has an absorption rate limit per hour of 30g. But here’s the deal with Fructose. It gets metabolized almost exclusively by the liver into glucose, fats and lactate as fuel.

That’s good to know because, fructose delays energy delivery, and you don’t need to take any more than 30g per hour.

The desired ration of glucose and fructose is 2/1

The good news is that there are plenty of gels out there with this ratio and blend.

So the take home is this

* NO carbohydrate in isolation can be oxidized for energy above 60g.

* Consuming a glucose/maltodextrin and fructose mixture increases carbohydrate absorption to 90g per hour.

* Gels with Maltodextrin have a fast absorption rate.

* If your buying energy bars make sure that the carb content is as close to 60g as possible.

* Over consumption carbohydrates in the form of gels is unnecessary and may well cause GI distress.

Thanks for reading

Simon de Burgh

2 X Winner of Gym Based PT 

Level 2 British Triathlon Coach 

Performance & Nutrition Director


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