Holmer posts study where 10g of carbs an hour beats placebo

Brady Holmer posted a study summary saying 10 grams of carbohydrate per hour, which he calls a fraction of what endurance guidelines recommend, beat a placebo for endurance fueling.

The detail that makes it land is the size of the effect. In Holmer's summary, that tiny dose stopped blood sugar from crashing and extended time to exhaustion by 22 percent. It did that in athletes adapted to a very-low-carb diet and in athletes adapted to a high-carb diet, so it was not just a rescue for people running on empty by design.

Why the number is loaded

Ten grams an hour is a number that has been argued over all week. It came up earlier in the opposite direction, which is exactly why Holmer dropping a study pointing the other way got the reaction it did.

David Roche replied that it was the rare moment when posting an objective study summary can also be scientific trolling. That is the whole temperature of the thread in one line. Nobody in it argued that 10 grams an hour is a race-day fueling plan.

David Roche

@MountainRoche

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The rare moment when posting an objective study summary can also be scientific trolling

What it actually means

Time to exhaustion in a lab is not a marathon. It is a test where you hold an effort until you cannot hold it any more, and 22 percent longer in that setting does not translate to 22 percent more anything at goal pace over 26.2 miles. The finding is that a very small amount of carbohydrate is not the same as nothing, not that a very small amount is enough.

So if you are fueling a fall marathon, this changes nothing about your plan. What it does change is how you read the next person who tells you a low dose is pointless. Holmer's post is the counterexample, and it covers low-carb and high-carb adapted athletes alike.