TOOLBOX: Cyclists are being encouraged to consume more carbohydrates than ever, with some professionals reporting 100–150 grams per hour. But does ultra-high carbohydrate intake improve performance—or simply send more unabsorbed sugar through your gut? Recent research challenges the assumption that more fuel always means more speed.
~I follow a mix of sports and nutrition accounts on Instagram, and it seems that every week another professional cyclist or triathlete posts the fueling numbers from a major stage or race. Increasingly, those numbers exceed 90 grams of carbohydrate per hour—and sometimes climb as high as 120 or even 150 grams.
I’ve also been increasing my carbohydrate intake during longer and harder rides this year. If I’m honest, seeing what the professionals consume makes it tempting to keep pushing that number higher. If 60 grams per hour is good and 90 grams is better, surely 120 grams must produce even more performance.
That assumption sits at the centre of endurance sport’s current “carb revolution.” But a recent opinion paper published in Sports Medicine examined the research behind ultra-high carbohydrate intake—and found that the evidence may not support the idea that more fuel always means more speed.
I get the logic. I wrote about bonking not long ago – fueling with enough carbs so you don’t run your tank dry mid-ride – and the takeaway was simple: under-fuel and you’ll pay for it. So if 60 g/hr is good & 90 g/hr is better, surely 100, 120, even 150 g/hr (what’s now called Ultra-High Carbohydrate, or U-HC, intake) must be better still?
That’s the logic behind the current “carb revolution.” A recent opinion paper in Sports Medicine (Plews et al., 2026) decided to actually test that assumption against the research. Their answer consolidates a variety of studies far better than any anecdotal evidence – and I found it worth sharing, because I think a lot of us (myself included) have been quietly assuming more carbs equals more performance, without checking whether that’s actually true.
The Carb Ceiling!
The case for eating more carbs has typically rested on three ideas: it spares your body’s own glycogen stores, it keeps blood sugar steady, and more of it gets burned as fuel the more you eat. As it turns out, all three ideas top out well before U-HC territory.
On glycogen-sparing: the research shows this effect is small & doesn’t keep scaling up with higher doses. Blood sugar, too, can be kept steady on fairly modest amounts – you don’t need to be guzzling 3+ gels per hour for that. And several controlled studies found that increasing from 90 up to 120 g/hr did increase how much of the carbohydrate you ate got burned, but it did not reduce how much of your own stored carbohydrate you burned in the process. That was the whole point of eating more carbs in the first place – and the evidence suggests it’s not happening.
There’s a second issue I hadn’t appreciated before this paper: the more you eat, the worse a job your gut does actually absorbing. One study found that at 90 g/hr, your body actually uses about 86% of what you swallow – but at 120 g/hr, that drops to 76%. That’s roughly 30 grams an hour just… passing through, doing nothing, while potentially contributing to gut trouble along the way.
And performance – the most important aspect for riders who race? The few studies that tested performance directly (such as TT’s) found performance gains from carbs up to somewhere around 60-90 g/hr, then the curve goes flat. So beyond 90 g/hr, more carbs didn’t directly relate to any improved performance.
So to these authors, the traditional case for eating beyond 90 g/hr simply doesn’t hold up.
Three Unproven Ideas
The paper’s authors (to their credit) go looking for why professionals still swear by huge carb numbers, and offer three ideas. They’re upfront that none of these are proven; they are simply educated guesses.
- Burning carbs is perhaps more “fuel efficient” than burning fat. True, in a lab sense – carbs give you slightly more energy per breath of oxygen than fat does. The theory is that flooding your system with carbs might lower your body’s oxygen cost during a long ride. Nice idea, in theory, but when researchers pooled the data across sixteen studies, there was no real effect either way (not to mention pretty wide variability in those studies).
- Lactate as extra fuel. Fructose (a type of sugar) gets converted to lactate in the liver, and lactate itself can be burned for fuel, especially by well-trained athletes. Interesting, except your gut can only absorb so much fructose per hour (roughly 30–60g), so at true U-HC doses, a lot of the fructose you’re drinking may never even get used this way.
- A mental/brain effect. Just having carbohydrate in your mouth (before you even swallow it) can measurably improve performance in some studies, likely by tricking your brain via taste receptors. But this effect shows up mostly in shorter, harder efforts, not the long, steady rides where U-HC often gets used. The researchers speculate it may play a smaller role over many hours.
All three ideas are plausible (at least on paper), but none are yet proven.
You Are (Probably) Not the Exception
For me, this was the most interesting & applicable part of the paper, especially to most amateurs: not everyone processes carbs the same way. In one study, athletes given the exact same 120 g/hr dose burned wildly different amounts of it – some used almost all of it, others could only actually use about 78 g/hr worth, with the rest going to “waste” and potentially leading to GI discomfort if the study’s sessions were a bit longer. Bigger athletes also tend to have a higher absolute ceiling. So yes, there’s likely a small group of genetically gifted, heavily gut-trained elite athletes for whom huge carb numbers (100+ g/hr) makes sense.
One caution worth flagging: the researchers noted that consistently elevated daily carb intake (the kind of habitual diet that “gut-training” for higher tolerance requires) was linked to pre-diabetic blood sugar patterns in about 30% of athletes studied over a month, though this reversed once intake came back down. That’s a different exposure than fuelling one big event now and then, but it’s a good reminder that chasing a higher carb intake might affect more than just your training.
To help wrap this article up & as a practical starting point, I would refer you to Jeukendrup’s well-known 2014 fuelling chart:
The current evidence doesn’t suggest that cyclists should fear carbohydrates. Under-fueling remains a reliable way to undermine a long or difficult ride. But avoiding the bonk and maximizing carbohydrate intake are not necessarily the same goal.
For most recreational and competitive cyclists, 60–90 grams per hour remains a sensible target for long, demanding rides. Going beyond that may work for some large, highly trained and carefully gut-trained athletes, but the performance advantages remain uncertain – and the gastrointestinal consequences can be very real.
The smartest fueling strategy isn’t the largest number you can tolerate. It’s the amount your body can absorb, use and consistently handle while allowing you to perform at your best.
So, next time I’m tempted to nudge my own numbers up past 90 g/hr because “it’s what the pro’s do”, I’ll remind myself I’m not chasing the same engine, or the same gut-training, they’ve spent years building. Sixty to ninety grams an hour, mixed well, is still the smart bet for the rest of us.
Stay safe, ride fast, & see you next time!
FAQs
How many carbs per hour should I consume while cycling?
For long or intense rides, approximately 60–90 grams of carbohydrate per hour is a practical target for many trained cyclists. Shorter or easier rides may require considerably less.
Do cyclists need more than 90 grams of carbs per hour?
Most cyclists probably do not. Some elite, larger or extensively gut-trained athletes may tolerate and use more than 90 grams per hour, but research has not consistently demonstrated additional performance benefits.
Is 120 grams of carbohydrate per hour too much?
It may be too much for many cyclists. Research suggests that the percentage of ingested carbohydrate that is absorbed and used can decline as intake increases, potentially leaving more carbohydrate in the digestive system.
Why do professional cyclists consume so many carbohydrates?
Professional riders compete at exceptionally high intensities for several hours and often train their digestive systems to tolerate large carbohydrate intakes. Their requirements and tolerance may not translate directly to recreational cyclists.
What is gut training?
Gut training involves gradually practising a race-day fueling strategy during training. This may improve comfort, carbohydrate absorption and tolerance, but it should be introduced progressively.
What type of carbohydrate is best during cycling?
At higher intakes, products combining glucose or maltodextrin with fructose are generally used because the body can absorb these carbohydrates through different intestinal transport pathways.
Can too many carbs cause stomach problems while cycling?
Yes. Consuming more carbohydrate than your digestive system can tolerate may contribute to bloating, nausea, cramping, gas or diarrhea.
Do I need carbohydrates for a one-hour bike ride?
Most cyclists beginning a normal one-hour ride with adequate energy stores do not require significant carbohydrate during the ride. A carbohydrate mouth rinse or small amount may still be useful during short, very intense competition.
References:
Plews DJ, Booth PD, Krieger T, Maunder E. Fuelled or Fooled? Examining the Evidence and Mechanisms Behind Ultra-High Carbohydrate Intake in Endurance Athletes. Sports Med. 2026 Jun 8. doi: 10.1007/s40279-026-02462-z. Epub ahead of print. PMID: 42258036.
Jeukendrup A. A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Med. 2014 May;44 Suppl 1(Suppl 1):S25-33. doi: 10.1007/s40279-014-0148-z. PMID: 24791914; PMCID: PMC4008807.
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