How Many Carbs Do You Actually Need?

gels, bars, blocks and a banana

Most endurance athletes are consuming more carbohydrate than they need during training and racing. Not by a little. By a lot.

The 90 grams per hour recommendation that became standard in endurance sports over the last decade was built on research conducted with elite athletes doing sustained high-intensity work. It got applied to everyone else regardless of size, intensity, duration, or individual metabolism. The result is a generation of athletes with complicated fueling plans, chronic GI distress, and no clear sense of whether any of it is actually helping.

A 2025 study published in Performance Nutrition found that when carbohydrate intake was personalized based on individual oxidation capacity, athletes averaged 65 grams per hour, not 90, with identical performance outcomes, lower perceived effort, and significantly less stomach discomfort. Individual capacity ranged from 42 to 80 grams per hour across the group. Feeding everyone the same number guarantees that some athletes are taking in far more than they can use.

Registered dietitian Uri Carlson of Innerwild Nutrition, who works with endurance athletes from weekend gravel riders to Unbound and Ultra competitors, sees this play out constantly. Her approach is simple: find your baseline, add 10 grams per hour at a time, and assess how you actually feel during the effort, in recovery, and the next day. Most athletes, she says, perform just as well or better at 40 to 60 grams per hour once they find their individual ceiling.

The bigger issue is that fueling is a skill, not just a number. Athletes who struggle on race day with nutrition are almost always athletes who never practiced their fueling strategy in training. What you eat, how much, and how you execute it under pressure all need to be trained the same way everything else is.

I sat down with Uri to dig into all of this, the history of how recommendations got so inflated, what the newer research is showing, how to figure out what you actually need, and how to build the habit of fueling with intention rather than just reacting when you remember.

The full conversation and article are on Substack.