NutritionAnswer

SHOULD I EAT LOW-CARB OR HIGH-CARB FOR CYCLING?

By Anthony WalshRoadman CyclingUpdated 26 May 2026

WHO THIS IS FOR

IS THIS YOU?

The rider tempted by low-carb for weight loss

You have heard low-carb burns more fat and are wondering whether to cut carbs to get leaner without wrecking your riding.

The cyclist confused by conflicting online advice

One source says carbs are king, another says fat adaptation is the secret, and you cannot tell which applies to your training.

THE ROADMAN VIEW

This debate is mostly settled at the top of the sport, and it went the way of carbohydrate. Anthony has had World Tour nutritionists on the podcast describe how the pro peloton went the opposite direction to the low-carb trend — fuelling rates climbed from 60g an hour to 90, 120, even Ben Healy's reported 140g an hour. You do not push fuelling that hard if carbs are the enemy. They are the fuel that lets the best riders in the world hold the power they hold.

The low-carb case rests on a real fact: train your body without carbohydrate and it gets better at burning fat. The problem is that fat is a slower fuel. It cannot release energy fast enough for threshold efforts, sprints, or hard climbs. So you become superbly efficient at the intensity that does not matter and worse at the intensities that decide races. Dr Sam Impey has made this point plainly — you train one energy system while competing on another.

Where it gets useful is periodisation, not picking a team. The smart move is high-carb when it counts and lower-carb when it does not — full carbohydrate on hard and long days, leaner on easy and rest days. That is fuel for the work required, and it gives you the metabolic flexibility benefits people chase with low-carb without paying the performance tax on the days that actually build fitness.

EXPERT EVIDENCE

WHAT THE EXPERTS SAY

Dr Sam ImpeyWorld Tour nutritionist
Carbohydrate availability is the single biggest dietary lever on high-intensity performance. Fat-adaptation strategies reliably increase fat oxidation but blunt the ability to produce power at race intensities, because fat simply cannot be metabolised fast enough. For any rider who trains or races hard, high carbohydrate availability around the key work is non-negotiable.
Hear it: Why Pros' 120g Carb Rule Fails Amateurs | Roadman Cycling
Dr Tim PodlogarNutrition consultant to Tudor Pro Cycling
The trajectory of professional fuelling has moved firmly toward higher carbohydrate intake, not lower. Riders now train their guts to absorb 90g an hour and beyond because more available carbohydrate translates directly into sustained power. Low-carb approaches are reserved, at most, for low-intensity sessions where fat oxidation is the deliberate target.
Hear it: Race Weight & Carb Timing Mistakes | Roadman Cycling Podcast

PRACTICAL APPLICATION

DO THIS WEEK

Periodise daily carbs to the work
Set carbohydrate by the day's demand: 5–6g/kg on easy and rest days, 7–8g/kg on moderate days, 10–12g/kg on hard sessions and race days. For a 75kg rider that ranges from roughly 375g to 900g. The total follows the training, not a fixed daily rule.
Fuel hard sessions and races with 60–90g per hour
Any session over 90 minutes or with hard intervals gets in-ride carbohydrate at 60–90g per hour using a glucose-fructose mix. This is the practical end of high-carb — keeping blood glucose and glycogen available so power holds to the finish.
Use lower-carb only on short, easy rides
If you want the fat-oxidation stimulus, restrict carbs only on a short, genuinely easy zone 2 ride — under 90 minutes, fully conversational. Keep carbs high everywhere else. This captures the metabolic upside of low-carb without sacrificing the hard-day power that builds fitness.

COMMON MISTAKES

WHAT CYCLISTS GET WRONG

MISTAKEGoing low-carb across the board to lose weight.
FIXWeight loss is driven by total calories and protein, not carb cutting. Stay high-carb around training, run a small deficit elsewhere, and you lose fat without losing power.
MISTAKEDoing hard intervals on a low-carb diet.
FIXFat cannot fuel high intensity fast enough. Carb up before and during hard sessions so the power and the adaptation are there.
MISTAKEEating the same high carbs every day regardless of training.
FIXPeriodise. Full carbs on hard and long days, leaner on easy and rest days — fuel for the work required rather than a flat daily number.

FAQ

FREQUENTLY ASKED QUESTIONS

Is low-carb ever better than high-carb for cycling?

Only for a narrow purpose: short, easy sessions where you want to nudge fat oxidation up. For anything hard, long, or competitive, high carbohydrate availability produces more power and better adaptation. Low-carb does not improve race performance — it improves fat burning at intensities that do not decide races.

Will eating high-carb make me gain weight?

Not if total calories are controlled. Carbohydrate fuels training and refills glycogen; it only adds fat if you eat more energy than you burn. Plenty of lean pros eat very high carb because they periodise it around heavy training loads. Manage total calories and protein, and high carb intake supports performance without adding fat.

What is fat adaptation and does it work for cyclists?

Fat adaptation is training the body to rely more on fat for fuel by chronically restricting carbohydrate. It reliably increases fat oxidation, but research shows it impairs exercise economy at high intensity and reduces the ability to use carbohydrate when you need it. For performance-focused cyclists, the trade-off is a net negative.

How many carbs should I eat per day for cycling?

Between 5 and 12g per kg of bodyweight, scaled to the day's training. Easy and rest days sit at the low end, hard sessions and race days at the high end. A 75kg rider might eat 375g on a rest day and 750–900g before a big event. The total tracks the work, not a fixed figure.

Can I cycle on a ketogenic diet?

You can ride easy on keto, but high-intensity and prolonged hard efforts suffer because the body cannot access carbohydrate quickly when it matters. Studies on keto in endurance athletes consistently show reduced economy and power at race intensities. For recreational easy riding it is workable; for performance it is a handicap.

Does low-carb training improve metabolic flexibility?

Occasional low-carb easy sessions can improve the body's ability to use fat at low intensities. But you do not need a full low-carb diet for this — periodising a few easy rides with low carbohydrate availability captures most of the benefit while keeping hard days fully fuelled, which protects performance.

RELATED EPISODES

HEAR THE CONVERSATIONS

Why Pros' 120g Carb Rule Fails Amateurs | Roadman Cycling

Race Weight & Carb Timing Mistakes | Roadman Cycling Podcast

Ben Healy's 140g/hr Fueling Strategy | Roadman Cycling