We are talking about how much carbohydrate you need to eat to fule an Ironman or similar endurance event. In most casses the answer to this is probably yes but more through luck more than judgement.

The truth of the matter is that while your energy expenditure while running is proportional to body weight unfortunately the current best research shows there is a poor correlation between body weight and your ability to absorb carbohydrates without being sick.

How does this make sense? I’d suggest that a 5’2″ athlete will have a smaller gut and be able to absorb less than a 6’2″ athlete this is fairly obvious.

However it is also obvious that every athlete that is say 6’0″ is not the same weight and this can vary hugely from mid 60 to 100+ kg. In this situation there is certainly going to be a poor correlation.

This plot is meta-analysis data which means basically all the relavent studies have been put together and combined to give a more complete picture of whats happening. The result is that there is NO correlation between body weight and your ability to use ingested carbohydrate.

So the rule of thumb 1-2g of CHO per kg per hour is nice but in reality for most of us we are looking at a more absolute number irrespective of weight.

For most people this is 30-90g of carbs per hour and more is better but it needs to be well tolerated.

Fortunately you can train your gut in a similar way you can train your muscles so in workouts approaching a big race start working on your nutrion.

Start modestly maybe with a gel every 40 or 60 min and try to increase this ideally to a gel or the equivalent every 20-30min.

If you find it too much, reduce it, but do try and increase it again in the future because the “training” effect means your capacity will increase.

Finally, dont try and increase your intake on race day…. just as with pacing stay within your limits. Push your limits in training and sit just under this level for your race.