120g of Carbohydrates Per Hour — Really?

Somewhere in the past few years, 120g of carbohydrates per hour became a number that endurance athletes started throwing around like a target. You hear it on group rides, in training forums, in race reports. It comes from legitimate research and real-world data from professional cycling. It also may be the wrong number for most of the athletes using it.

Where 120g Comes From

The push toward very high carbohydrate intake during exercise is grounded in solid science. Research has consistently shown that athletes can oxidize more carbohydrates than was once believed — particularly when those carbohydrates come from multiple sources that use different intestinal transporter pathways (Rowlands et al., 2015). Early studies capped useful carbohydrate intake at around 60g per hour for glucose-based products. Later work on multi-transporter carbohydrates pushed that ceiling significantly higher.

In elite sport, this translated into professional cyclists consuming 100–120g of carbohydrates per hour during grand tours. The results were compelling. The question is what those results actually tell us.

What Those Athletes Have That Most Don't

Professional cyclists spending five or six hours in the saddle at high intensity have two things that most everyday athletes don't.

The first is years of gut adaptation. The gastrointestinal system responds to training just as muscles do. Athletes who have consistently consumed high volumes of carbohydrates over many years develop greater intestinal tolerance and absorption capacity. A trained gut at 120g per hour is a different system than an untrained one attempting the same intake.

The second is team nutrition infrastructure. Professional athletes have dietitians, sports scientists, and support staff managing their fuelling in detail. Their protocols are individually calibrated. The number that works for a Tour de France rider at their specific intensity, bodyweight, sweat rate, and gut capacity is not a universal prescription.

The Efficiency Argument

Here's what the research actually shows when you look at oxidation rather than intake volume.

At 90g per hour using a 2:1 glucose-to-fructose formula, approximately 86% of ingested carbohydrates are oxidized and utilized as fuel. At 120g per hour using a less optimized ratio, oxidation efficiency drops — meaning more of what you consume passes through without becoming usable energy, and the excess sits in the gut creating the conditions for distress (Podlogar et al., 2022).

More carbohydrates consumed does not automatically mean more carbohydrates utilized. The formula and the athlete's adaptation level determine that.

The Right Question

The question isn't what the maximum carbohydrate intake in elite sport has been demonstrated to be. The question is what your gut can actually absorb and convert to usable energy at your training intensity, with your current level of adaptation, and at a rate you can sustain for hours without discomfort.

For most everyday athletes training at moderate to high intensity, 60–90g per hour from a 2:1 formula is the evidence-based target. It's achievable, it's efficient, and it's a level that can be trained toward systematically.

Chasing 120g before you've built the gut tolerance for it tends to produce one outcome: a long ride home with a very unhappy stomach.