NEW STUDY CONFIRMS MOST CYCLISTS FUEL WRONG — DR SAM IMPEY | ROADMAN CYCLING PODCAST
with Sam Impey — World Tour performance nutritionist and researcher in carbohydrate metabolism; works with professional cyclists including Tom Pidcock and Filippo Ganna
Dr Sam Impey is one of the WorldTour-facing performance nutritionists most relevant to the modern fuelling conversation — working with Tom Pidcock and Filippo Ganna at the elite level, advising Exo Analytics, and publishing on carbohydrate metabolism. His usefulness for the Roadman audience is that he is the rare practitioner willing to publicly say: stop copying the 120g/hr pro number — that protocol is built for 8–12 g/kg/day workloads across 20–30 hours of training and is the wrong starting point for amateurs.
01The mistake isn't on the bike, it's across the week. Most amateurs fuel every session the same way. The pro pattern is to match carbohydrate to the demand of each specific session — big on the hard and long days, lighter on the easy ones. That whole-week matching is "fuel for the work required."
02Amateurs mostly under-fuel the sessions that matter. The hard intervals and the long endurance rides are where fuelling changes the outcome, and they're exactly the ones riders skimp on — then wonder why the legs are flat and the progress has stalled.
03Stop copying the 120g/hr number. That figure is built for professionals doing huge daily energy outputs across 20–30 hours of training a week. For most amateurs a starting point of around 60 grams an hour — one gram a minute — is more appropriate, then build from there as the gut adapts.
04Above threshold, glycogen burn goes exponential. The reason fuelling targets climb for hard efforts isn't intensity for its own sake — it's that at and above FTP you deplete glycogen far faster, so the cost of under-fuelling those sessions is much higher.
05Protect training quality above all. If a fuelling or weight-loss choice makes your key sessions worse, it's the wrong choice. The scale is a poor master; the quality of the work you can actually do is the thing that moves fitness.
The headline is a bit of a wind-up, and Sam Impey knows it. "Most cyclists fuel wrong." You've heard some version of that a hundred times, usually right before someone tries to sell you a gel. So when I got Sam — who fuels riders like Tom Pidcock and Filippo Ganna at the very top of the sport — back on the podcast to talk about a new study confirming it, the first thing he did was tell me the mistake isn't where you think it is.
Key Takeaways
Here's the part that surprised me. When we say cyclists fuel wrong, everyone immediately pictures the bike. Not enough gels. Wrong drink mix. The bonk 60k from home. And sure, that happens. But that's not the pattern the research is pointing at. The real mistake plays out across the whole training week, off the bike as much as on it.
Most amateurs fuel every session roughly the same. Easy ride, hard intervals, long endurance day — same rough approach to food around all of them. The essence of how the pros eat is the opposite: they match the carbohydrate to the demand of the specific session in front of them. Big fuelling for the hard days and the long days, lighter on the genuinely easy ones. That's it. That's the whole idea the sports-science world calls "fuel for the work required," and it's the thing that quietly separates amateur fuelling from professional fuelling.
And here's the sting in the tail: when amateurs get it wrong, they almost always get it wrong in the same direction. They under-fuel the sessions that actually matter — the hard intervals, the long rides — and over-fuel the easy ones. Which is exactly backwards. Then they wonder why the legs are flat and the progress has stalled.
Why It's Not A Gel Problem
The reason this matters is that the "eat more gels" framing lets you off the hook. It turns fuelling into a shopping problem — buy the right product, stuff it in your pocket, done. But if the real issue is how you fuel across a whole week, no product fixes it. Only a change in how you think does.
Impey's framing is that fuel changes the cost of the work. How much carbohydrate you have available doesn't just top up the tank — it changes how much stress a given session puts on your body, and how well you adapt from it. Turn up to your hardest session of the week under-fuelled and you don't just feel worse. You do worse work, and you adapt less to the work you managed. The session was the point, and you blunted it before you started.
That's why the direction of the amateur mistake is so costly. Under-fuelling the easy day doesn't cost you much — your body handles a steady spin on fat and stored carbohydrate just fine. Under-fuelling the hard day costs you the one session that was going to move your fitness.
The 60 Versus 120 Question
If you've spent any time on cycling social media, you've absorbed the number: 120 grams of carbohydrate an hour. It's what the pros are doing, it's plastered over every fuelling brand's marketing, and it has quietly become the amateur's target too.
Impey's been clear on this for a while, and he was clear again here: that number is not your starting point. It's built for professionals producing enormous daily energy outputs across twenty to thirty hours of training a week, with guts trained over years to absorb that volume of carbohydrate. Lift it straight into an amateur's ride and you're as likely to end up hunched over with gut distress as flying.
A sensible starting point for most riders is around 60 grams an hour — one gram a minute — and then building up from there as your gut adapts. The gut is trainable, which is the good news, but it's trained over weeks, not bolted on the morning of your big event. Start sensible, protect your key sessions, and earn the higher numbers.
The reason the target climbs at all for hard efforts is worth understanding, because it's not arbitrary. At and above your threshold, glycogen depletion goes exponential — you burn through stored carbohydrate far faster than you do on an easy ride. So it's not that intensity magically demands more food for its own sake. It's that the harder you go, the quicker you empty the tank, and the more it costs you to have turned up half full.
What This Means For Your Riding
You don't need a spreadsheet and you don't need to copy a pro's numbers. You need to stop fuelling every ride the same.
Look at your week and sort your rides into the ones that matter and the ones that don't. The hard interval sessions and the long endurance rides are where fuelling changes the outcome — fuel those properly, starting around 60 grams an hour and building as you adapt. The genuinely easy days need far less, and that's fine. Match the food to the job.
And keep the scale in its place. If a fuelling or weight-loss decision is making your key sessions worse, it's the wrong decision, full stop. Training quality is the thing that makes you faster, and it's the thing your fuelling should protect above all.
If you're already training hard and the results aren't following, fuelling is one of the first places the leak usually hides — but it's rarely the only one. That's exactly what the Plateau Diagnostic is built to find. Three minutes, free, and it looks at the whole picture rather than one symptom.
You Might Also Like
For Sam's full reset on in-ride fuelling — the 60-grams-an-hour starting point and why eating more is usually the upgrade — read The World Tour Fuelling Reset. For the wider view of how the best nutritionists in the sport actually think, the World Tour nutrition guide pulls it together. And if you want to hear the fuelling conversation from another angle, We Got Fuelling Wrong is the natural next listen.
Want to put this into practice with people who actually train seriously? That's what the Roadman community is for.
CLAIMS FROM THIS EPISODE
Each tagged with the strength of evidence behind it.
EXPERT
Dr Sam Impey is a World Tour performance nutritionist who works with professional cyclists including Tom Pidcock and Filippo Ganna and researches carbohydrate metabolism.
Source: Sam Impey, Roadman Cycling Podcast; guest profile and public records
STUDY
"Fuel for the work required" describes matching carbohydrate intake to the specific energetic demand of each training session rather than fuelling uniformly.
Source: Carbohydrate periodisation research ("fuel for the work required"), discussed by Sam Impey on the Roadman Cycling Podcast
EXPERT
Impey's guidance is that a sensible in-ride fuelling starting point for amateurs is around 60 grams of carbohydrate an hour, rather than the roughly 120 grams an hour that professionals target.
Source: Sam Impey, Roadman Cycling Podcast
STUDY
At and above threshold intensity, glycogen depletion accelerates sharply, which is why fuelling demands rise most for hard efforts.
Source: Exercise physiology of glycogen utilisation, as explained by Sam Impey on the Roadman Cycling Podcast
FREQUENTLY ASKED QUESTIONS
What do most cyclists get wrong about fuelling?+
According to Dr Sam Impey, the biggest mistake isn't on the bike with gels or drink mix — it's a pattern across the whole training week. Most amateurs fuel every session roughly the same, whereas the essence of how pros eat is matching carbohydrate intake to the demand of each session. That means fuelling the hard intervals and long rides properly while easing off on genuinely easy days, rather than treating every ride the same.
What does "fuel for the work required" mean?+
"Fuel for the work required" is the principle of matching your carbohydrate intake to the specific energetic demand of each session rather than eating the same amount regardless. Big fuelling for the hard and long days when your body needs the carbohydrate to perform and adapt; lighter fuelling on easy days. It's the framework behind how professional teams periodise nutrition across a training week.
How many carbs per hour should an amateur cyclist eat?+
Impey's guidance is to start at around 60 grams of carbohydrate an hour — one gram a minute — rather than copying the roughly 120 grams an hour that professionals target. That pro number is built for enormous daily training loads and a gut trained over years to handle it. Start at 60 grams, protect your key sessions, and build up gradually as your gut adapts.
Why do hard sessions need more fuelling than easy ones?+
Because glycogen depletion accelerates sharply at and above threshold intensity. On an easy ride your body leans more on fat and burns through stored carbohydrate slowly; on hard efforts you deplete glycogen far faster. That's why under-fuelling your hardest sessions is so costly — it's exactly when carbohydrate availability changes what you can produce and how well you adapt.
Does under-fuelling stall training progress?+
It can, and Impey argues most amateurs are under-fuelling rather than over-fuelling. When you consistently under-fuel your hard and long sessions, you compromise the quality of the work and the adaptation that follows — flat legs, stalled progress, and sessions that don't deliver what they should. Fuelling the important sessions properly is usually the upgrade.
Should you fuel for weight loss or for performance?+
Impey's position is that training quality should be the thing your fuelling protects. Chasing the scale by under-fuelling wrecks the sessions that actually make you fitter. A modest, sustainable approach that keeps your key sessions fuelled — rather than an aggressive deficit that degrades them — is what works over time. The quality of the work you can do matters more than a number on the scale.
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