Researcher says new data kills the 10g carbs an hour claim

Researcher Javier Gonzalez says the claim that 10 grams of carbohydrate per hour is enough to prevent hypoglycaemia during exercise has been disproved. Hypoglycaemia is blood sugar dropping too low, the thing a bonk feels like from the inside.

In his post, Gonzalez writes that some have argued 10 grams per hour is sufficient, and that the latest data from @HenryJMartyn and @JamesyMorton clearly disprove it. He credits the finding to those two researchers rather than his own work.

Javier Gonzalez

@Gonzalez_JT

X

Absolute statements only need a single observation to be disproved.

He also makes the logic explicit. An absolute statement, the kind that says a number is always enough, falls apart the moment one case shows otherwise. That is the whole argument he is making, and it is a narrow one.

What it actually means

This is one researcher reading one dataset and pushing back on an absolute claim. He is not proposing a replacement number, and nothing here tells you what to put in your flask on Sunday. The useful takeaway for a marathoner is smaller and more boring than the headline sounds. If you have heard that a very low hourly carb intake is all anybody needs to stay out of trouble, at least one researcher says the data do not support stating that as a rule.

It is worth keeping the scope straight. Gonzalez's post is about preventing low blood sugar, not about performance, not about gut training, and not about the much higher hourly intakes that race-day fuelling guides tend to talk about. Those are different questions with different evidence behind them.

The reaction so far has been short. Brady Holmer replied with a single line, "Bad day to be 10 grams of carbs."

Brady Holmer

@Brady_H

X

Bad day to be 10 grams of carbs.

So treat this as a claim being knocked down rather than a new target being set up. Until the data behind it get read and argued over by more people in the sport, the honest summary is that one well known carbohydrate researcher says the 10 grams an hour line should not be stated as an absolute. If someone quotes it back at you as settled science, that is now the part that is in question.