What does an ultra-endurance cyclist eat?

jill
October 21, 2024

Be honest, have you clicked on this expecting mars bars and gummies, or gels and chews, with the odd banana thrown in?

To race non-stop over 24, 40 or 100+ hours does raise the question – what the hell does an ultra-endurance cyclist eat to keep going? 

I’ve managed many ultra-endurance cyclists over races of various lengths and times, including World Champ and ultra-cycling World Cup winner Joe Barr. I’ve been roadside for many of them, looking at tired faces, sore muscles and swollen guts.

Mistakes? I’ve made them, but I’ve learned, and I’ve crossed the finish line, more than a few times, with my rider on the podium.

Here’s how I approach it, and while this guide is mainly for a supported ultra-cyclist, who has a crew, much of it is equally applicable to the unsupported rider who stops in towns and villages to source food.

An ultra-endurance cyclist eats like this pre-start line

As a rider, your goal is to get to the start line as rested as possible with ample stores of macro and micronutrients. Never underestimate the nutritional cost of an ultra-endurance cycling race. You don’t want to finish injured or sick.

Nutritional resilience is built over time, so talk to a nutritionist who specialises in endurance, do some reading, and get your general (what I call off-bike) nutrition plan organised.

You might want to think about doing a carbohydrate load pre-race as you’re going to need every bit of stored, accessible energy you can get your hands on.

You’re not in Kansas anymore!

But as soon as you swing your leg over the bike, stop thinking about nutrition or micronutrients, and start thinking about fuel.

Fuel comes in the large macronutrient blocks of carbohydrate, protein and fat.

These are the substrates that generate chemical energy, Adenosine Tri-Phosphate or ATP. This is the energy you need to keep the bike moving forward.

During the race you can only get these fuel substrates from;

1. what you eat and drink

2. your stores – which come in three forms – glycogen (the storage form of carbohydrate), body fat, and protein, in the form of muscle (but let’s not use that).

How much should an ultra-endurance cyclist eat?

Your goal is not to match calorie output with input. 

First of all, that’s close to impossible and second, even if you matched calorie output, your gut would simply refuse to process that much, hour after hour.

Your gut is a muscle too. 

It’s a long and complicated one so when you fold it over the handle bars of a bike, divert blood supply away from it, it can get grumbly in the form of nausea, bloating, and gas.

As an ultra-endurance cyclist, you must treat your gut with respect.

A rough rule of thumb is to ingest 50% of your calorie output per hour. If you’re getting that consistently and comfortably, you’re in good shape.

Likely your Garmin, or whatever head unit you’re using, will give you a calorie output estimate. While this number is not specific, it’s the best you’ve got, so start there, assess, and modify.

What does an ultra-endurance cyclist eat?

Your tastes will change over time and can be very unpredictable. 

Sometimes you won’t be able to tolerate a bar you’ve been using for the last 6 months. Having options in the crew car, or your pocket, is critical.

The macronutrient breakdown of fuel options would usually equate to 60% carbohydrate (with an equal blend of simple and complex carbohydrate), 30% fat, and 10% protein.

All carbohydrate, both simple and complex, is eventually broken down or converted into glucose. The important thing is to manage the speed with which that glucose hits the blood stream.

Simple carbohydrate is absorbed quickly and hits the blood stream quickly.

Complex carbohydrate is absorbed slowly. It’s released into the blood stream in a more sustained manner, which is vital for ultra-endurance cyclists as sustained speed over time requires a steady supply of glucose.

An ultra-endurance cyclist should know their carbohydrates

You’ll get simple carbohydrate through your bottle mix. There are a multitude of different formulas and tastes out there. Sometimes it helps to have a couple of different flavours to choose from.

Some use glucose, others glucose and fructose, and a fair number use maltodextrin. Many formulas add electrolytes, amino acids and other performance aids, like caffeine.

Remember, all sugars eventually end up as glucose, which is your body’s basic unit of currency when it comes to creating energy (ATP).

I rarely recommend gels. Instead I prefer the steady supply of simple carbohydrate through the consistent sipping of bottle mix, versus a highly concentrated shot of 25-30 grams carbohydrate.

Smaller amounts delivered consistently is more friendly on the gut and more supportive of brain, muscular, and digestive function. 

Think of your bottle mix as your background energy operating system.

Complex carbohydrates – an ultra-endurance cyclist’s companion

The rest of your hourly carbohydrate intake comes from more complex sources, sources that contain fibre.

I use foods containing soluble fibre such as oats or rice. I buy bars, and I make bars. Check out the book by Biju Thomas and Allen Lim, Feed Zone Portables for some great bar recipe ideas.

Remember, having options with different tastes and textures are key. When it comes to fibre intake, it’s a balance, you don’t want to stop often for toilet breaks but you also don’t want to have an unstimulated gut that backs up.

I use croissants or more processed breads packed with salted butter, jam or nut butter.  On occasion I’ll even use thin sliced deli meats to give the palate a change from that overwhelming sweet taste.

The reason I recommend more processed breads is to offload some of the digestive ‘work’ from the gut, remember the gut gets fatigued too. We only ever use them during a race, in general life it’s high fibre all the way!

Blended soups are easy to pre-make and carry. They can also be found in cafes or even gas stations if you are an unsupported rider. They are rapidly absorbed and score high on the gut friendly scale. My favourite is this sweet potato and coconut milk. The complex carbohydrate from sweet potato, mixed with a medium chain fat like coconut milk, with some warming spices like ginger and coriander – performance heaven especially in the night time hours, and yes, you can drink it on the bike.

And finally, don’t rule out good old mashed potato and butter. Again, it’s relatively easy to make roadside with a gas stove or find a café that does baked potatoes.

These more complex foods become vitally important on a multi-day race.

Ultra-endurance cyclists eat fat!

Fats account for around 30% of total calories. I primarily use short chain fats like butter, medium chain fats like coconut, and long chain fats like nut butter and chocolate.

 All 3 fats have different absorption rates meaning some are more useful when the going gets tough versus a recovery window. At 9 calories per gram, versus 4 calories per gram of carbohydrate, fat is the most energy rich substrate, which makes it a valuable substrate.

Have a look at the fat grams in the bars that you buy, you want the carbohydrate to fat ratio to be around 2:1 (carb:fat) or at the very least 3:1 (carb to fat).

Protein power – not so much when you race

That leaves 10% of ingested calories coming from protein. 

Protein is not my first or second choice as a fuel substrate but it does provide an important function. 

Certain amino acids, the branch chain kind, are easily converted to glucose. 

They also are supportive of brain function and spare muscle breakdown.

And talking of brain function, I should say that coffee is a constant!

An ultra-endurance cyclist eats on the hour

Carbohydrate is the only macronutrient that I would have an hourly goal for. Remember, it’s your primary energy source.

The amount of carbohydrate is determined by average heart rate, gut comfort, and environmental conditions. 

A higher heart rate comes with a bigger energy cost, with carbohydrate meeting most of the burden.

A lower heart rate is a lesser energy cost, and with more oxygen available a significant portion of the effort can be met using energy stores like body fat.

When it comes to determining your hourly goal, a rough rule of thumb is 0.5-1.0 gram of carbohydrate per kilogram of body weight, although your nutritionist should determine where you are on that scale.

I always remain flexible, and never force feed a cyclist. The ability of the gut to take in volume changes over time, under different environment conditions, and as fatigue or sleep deprivation kicks in. It’s not about how much volume you can ingest, it’s about how much volume your gut can comfortably process.

It’s much easier to fix an under-fuelled situation than an over-fuelled one. Ask anyone who has over-fuelled how long it takes for gut distress to resolve!

Top-up feeds? Now you’re talking…

If the race is long, hourly feeds will not sustain performance without regular top-up feeds.

Top-ups feed are feeds ‘in addition’ to your hourly carbohydrate intake.

I plan them every 6-8 hours in the form of an extra 35-60g carbohydrates, primarily complex carbohydrates.

I often use single serving oatmeal pots as they can be taken on the bike and I’ve been known to add jam, nut butter or even chocolate to dial up the carbohydrate and fat content.

In the night time I go to blended soups. Again, it all depends what facilities you have in the crew car. 

Regular top-up feeds will help you manage the inevitable fuel depletion curve. We want a managed, slow, downward curve, not a fall off the edge of the cliff scenario!

A pre-sleep feed, an ultra-endurance cyclist’s recovery opportunity

The pre-sleep feed is the only opportunity to replenish those all-important stores and reverse the depletion curve. Most ultra-cyclists will sleep for 1-4 hours every 24-36 hours. 

The pre-sleep feed is all about high glycemic index foods that are broken down quickly to glucose.

This has the effect of spiking blood sugar levels quickly.

Once you step off the bike, your hormonal environment is primed to shunt glucose from the blood into muscles, to restore glycogen. We want to use this to our advantage, and encourage as much glycogen replenishment as possible.

The shunt of glucose to muscles results in a corresponding drop in blood sugar levels, called post-prandial depression. 

Ever felt sleepy or groggy after a big meal? This is exactly what we’re going for. 

Your glycogen levels can be completely restored while you sleep.

I often use a big bowl of mashed potatoes with added salt and butter, and at times I cook them in a rich stock to add electrolytes. It’s soft, savoury and salty which is the perfect taste compliment after all the sweet stuff. 

This is the one time where you can push the boat out with regards to food volume. 

When you wake up, be prepared to move your bowels! This can take some ultra-cyclists by surprise so make sure you’re parked or stopped in a place that can accommodate your needs.

Have a coffee, a carbohydrate-based snack to top up your blood sugar, and you’re ready to race again!

An ultra-endurance cyclist’s stored energy bank

You will inevitably rely on stored forms of energy.

Glycogen is the storage form of carbohydrate. It’s found in muscles and the liver. 

It’s limited to roughly 1800-3000 calories in muscles (dependent on muscle mass) and 400-500 calories in the liver.

Every athlete should go to the start line with as much glycogen as possible. This is why you do that carbohydrate load before the start line.

Glycogen is easily converted to glucose, the primary currency for energy creation. During the race you will draw on some of your glycogen stores each hour. The trick is not to make a significant withdrawal quickly. The hourly feeds plus the top-up feeds are designed to spare glycogen for as long as possible.

While glycogen is limited, body fat is not. Most cyclists have hundreds of thousands of calories stored, even lean ones!

Muscles (or the mitochondria in muscle, to be accurate) are well equipped to metabolise and oxidise fatty acids to create energy.

Burning body fat for energy – eureka!

Oxidising, or burning, body fat to create energy occurs under a particular set of conditions. Here’s what you need to know to make the most out of this valuable and unlimited energy source.

1. Fat oxidises more efficiently with some carbohydrate present – this is the function of the consistent carbohydrate sips from the bottle. 

2. It also oxidises better in medium to lower heart rate zones and in an oxygen rich environment. Most endurance athletes spend the majority of race here, making body fat a valuable source of energy.

3. The rate of fat oxidation can be trained. The best fat oxidisers can generate about 65% of their calorie needs in the above environments. Women are genetically more equipped to utilise fatty acids than men.

4. It takes more time to oxidise body fat, covert to glucose, and generate energy so if you need energy in a hurry, carbohydrate is still your best bet.

5. It’s better to utilise both carb and fat pathways when it comes to generating energy, so the goal really should be metabolic flexibility.

6. The best strategy to spare glycogen is to be highly efficient at oxidising body fat. You can work with your nutritionist to become a better fat oxidiser.

You’ve got muscle in your energy bank too

The last substrate that can be used to generate energy is protein in the form of muscle mass. 

When carbohydrate is low the body can release protein, in the form of amino acids, from muscles, and convert them to glucose.

This truly is a last resort. 

You muscle mass is your strength, vitality, and your performance. Using muscle as a fuel source is akin to having a beautiful wooden cabin and breaking it down for firewood.

If you have a good fuelling strategy in place, you should be able to avoid losing muscle mass in an ultra-endurance race.

You’re doing it right if…

You’re doing it right if you’re sipping consistently from your bottle, fuelling consistently with bar bites, topping up regularly with various solid foods, craving salty foods like pizza, drinking lots of coffee, getting those pre-sleep feeds in, experiencing taste fatigue, getting tired of eating and drinking, and even losing all sense of appetite.

But if I leave you with anything, let me leave you with this… you are more likely to get into trouble with over-fuelling.

Ultra-cyclists over-fuel for a multitude of reasons, which deserves a separate blog. Over-fuelling will eventually lead to gut distress, which can take hours to ease. 

Under-fuelling can be fixed in 20-30 minutes by taking on more fuel.

The moral of the story comes down to three little words – trust your gut.


I’m Jill – BarrUltra’s performance nutritionist. I work with ultra-endurance athletes who love to ride and race over distance. I create general nutrition plans, as well as training and race plans.

If you’ve got ultra-ambitions and want to dial in your nutrition and fuel. Contact me and let’s get going.