Fuelling Joe

Jillian Mooney
May 8, 2021

How do you fuel a man who is planning to ride for 100+ hours using approximately 500-700 calories per hour and who is only planning to stop for 60-90 minutes every 24-36 hrs?

It’s a scary prospect, even for me. I’ve managed Joe’s nutrition for races of similar length and intensity. I’ve made mistakes, learned and I’ve got it right at times too.

If you’re interested, here’s how I approach it.

Joe heads to the start line as rested as possible with ample stores of macro and micronutrients built up methodically over time. That is the job of off-bike nutrition.

(Note: It’s very difficult to ‘rest’ an elite athlete before a start line. The race is in their blood and it’s oh so tough to get him to S…L…O…W down).

As soon as Joe swings his leg over the bike I stop thinking about nutrition – I think FUEL.

I think only in large macronutrient blocks (carbohydrate, protein and fat), which are the substrates he needs to generate energy (Adenosine Tri-Phosphate) to keep the bike moving forward.

During the race he can only get these macronutrient fuel substrates from 2 sources:

1. what he eats

2. what he has stored in the form of glycogen, body fat and muscle

What he eats

The goal is not to match calorie output with input. First of all, that’s impossible to do and second, even if you got that amount of calories in, the gut simply can’t process and absorb that much hour over hour.

The gut is a muscle too. It’s a long and complicated one so when you fold it in two (assume race position) and divert blood supply away from it and to the muscles, it can get grumbly – nausea, bloating, gas, diarrhea.

You have to treat the gut with respect and flexibility. Push it too hard and it will simply rebel.

I run a small, a la carte menu from the service car. It’s usually service with a smile, however I do allow myself 10% grumpiness – coffee, no smile!

Joe’s tastes and preferences will change over time and can be very unpredictable. Sometimes his gut won’t tolerate a bar we’ve been using for the last 6 months.

Frustrating? Yes! I’ve learned that options are critical.

If you look at my food options they break down to 60% carbohydrate, which consists of 50% simple carb and 50% complex carb. The ratio of simple to complex changes depending on heart rate, perceived effort, gut function and outside conditions.

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

Simple carbohydrate is absorbed and used immediately, complex in a more sustained manner, which is vital when you consider just how far Joe is riding. Sustained speed over time needs a sustained blood sugar over time.

Our consistent source of simple carbohydrate is through the bottle mix – TRIFUEL. We don’t use gels, ever. We prefer the steady sipping and dripping of simple carb over time.

A steady low-medium supply of simple carb (20-30g per hour for Joe at 55kg) supports brain, muscular and digestive function while also supporting fat oxidation (more on that later).

The rest of our hourly carb goal (another 35-40g) comes from solids. I use foods with mainly soluble fiber. Oats, home made bars made from oats, blended sweet potato or lentil soups are my old faithfuls. They are rich in complex carbohydrate, easy to digest and the soluble fibre means they are less abrasive on a working gut. I run some extremely low fiber foods too (like mashed potatoes). When the body enters the extreme fatigue phase low fiber is less work for a tired gut. This is when some processed foods, like a broth or noodle soup, become a viable option. It’s probably the only time we ever use them but they really do work well.

When it comes to fiber it’s a balance, you don’t want to be stopping often for toilet breaks but you also don’t want to have an unstimulated gut that backs up.

Fats account for around 30% of total calories. We use short chain (butter), medium chain (coconut) and long chain (nut butter and chocolate) fats. All 3 fats have different absorption rates meaning some are more useful when the going gets really tough versus a recovery window. At 9 calories per gram versus 4 calories per gram of carbohydrate, fat is the most energy rich substrate. It’s a valuable macronutrient to understand.

That leaves 10% for 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 more easily converted to glucose, which is of course the most basic energy substrate of all. They also are supportive of brain function (excellent when you really get sleep deprived) and to prevent muscle breakdown.

This is why we love our TRIFUEL by BRL Sports Nutrition so much as it contains carb, electrolytes and branch chain amino acids.

I should say coffee is a constant.

How Much He Eats

We have a flexible hourly goal, which is determined mainly by average heart rate, the most valuable reflection of effort.

All endurance athletes should do the work of understanding what kind of calorie in versus calorie out ratio sustains performance and is achievable on the gut hour over hour. We’ll be trialing the Supersapiens performance biosensors under extreme race conditions for the first time. I’ll be able to scan Joe to see his live blood glucose levels! It’s always exciting to look at a new presentation of data and assess its usefulness in managing Joe and the race.

I work from a flexible hourly goal because it’s so much easier to fix an under-fuelled situation than an over-fuelled one. Ask anyone who has over-fuelled how long it takes for GI distress to resolve!

This next bit is important. The hourly feeds will not sustain performance by itself for long without regular top-ups (TU’s). Top-ups being in addition to the hourly feeds. And ‘for long’ I mean more than 5-6 hours.

The TU’s are critical and I am ruthless about them. Depending on average heart rate they will come every 3 or 4 hours in the form of 35-40g complex carbs, using oatmeal with added nut butter/honey/chocolate & coconut mix. In the nighttime I will likely go to blended soups.

These TU’s allow me to manage what I call the fuel depletion curve. A race of this length will have a depletion curve no matter how you fuel. Even if Joe doesn’t feel the immediate need for more fuel in that 3-4 hr window it still happens because we want a managed downward curve, not a fall off the edge of the cliff scenario.

The last kind of feed I work with is the pre-sleep feed. This one is super specific as it is the only time I have to replenish Joe’s glycogen stores. I focus on high glycemic index solids that are broken down to glucose quickly.. This has the effect of spiking blood sugar levels. When Joe is in a depleted state and off the bike, his hormonal environment is primed to shunt this glucose immediately into muscles to restore glycogen. This shunt causes a corresponding drop in blood sugar levels called post-prandial depression. Ever felt sleepy or groggy after a big meal? We roll Joe over and he’s gone to la la land. While he’s sleeping his glycogen levels are being restored, it does happen that quickly when the conditions are right.

We use simple mashed potatoes and add the best short chain fat there is, butter. Mashed spuds and butter, the ultimate comfort food! I add salt and at times cook them in a rich stock to add electrolytes. It’s mushy and salty which is the perfect taste compliment after all the sweet stuff. Joe looks forward to this feed about 2-hours out!

When he wakes he has a small complex carb based snack to top up his blood sugar and he’s off again.



For the endurance cyclist, reliance on storage forms of carb, fat and protein is a must.

Glycogen is the only storage form of carbohydrate found in muscles and liver. It’s pretty limited to around the equivalent of 1800-3000 calories in the muscles (dependent on muscle mass) and around 400-500 calories in the liver.

Every athlete wants to go to the start line with as much glycogen as possible. We do our own form of endurance carb-loading pre-race by running nutrition-light towards the end of some strategically planned training sessions and then bumping up carb recovery in the 12-hours post-session and following days. And by the way the pre-sleep feed is a highly effective race from of carb loading.

Glycogen is easily converted to glucose to make ATP. Joe will certainly draw on his glycogen to some extent each hour. The trick is not to make a significant withdrawal quickly. That’s why the hourly feeds plus the 3-4 hour TU’s is vital. It spares glycogen for emergency use.

When you’ve completely run out of it you’re in a very bad place so we pay attention to every hour, every TU and every pre-sleep feed.


While glycogen is a limited form of stored energy body fat is not! Muscles (well to be exact, the mitochondria in muscles ) are well equipped to oxidize fatty acids to generate energy.

A couple of things about oxidizing body fat;

1. fat oxidizes better with some carbohydrate present (this is the hourly feed and sips from the bottle working). Think about a candle needing a wick to burn. Carb is the wick needed to burn your body fat.

2. fat oxidizes better in medium-lower heart rate zones and in an oxygen rich environment so think sustainable power where you can breath deeply. Most endurance athletes spend the majority of race time here.

3. fat oxidation can be trained and current research tells us that the best fat oxidizers can generate about 60% of their calorie needs in the above environments.

4. it takes more time to oxidize body fats, covert to glucose and generate energy so if you need energy in a hurry and you’ve run out of carb….this is not a good place.

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

Joe will be relying on body fat stores for a significant proportion of his energy generation. The best strategy to spare glycogen is to be efficient at oxidizing body fat.


The last substrate that can be used to generate energy is protein in the form of muscle mass. This truly is a last resort. The body prefers to use carbohydrate and fat in either ingested or storage form to generate energy.

The use of muscle mass is something we try to prevent by having a good fuelling strategy in place.

Last thoughts

Hydration is critical. Joe has a small frame and overall mass so I’m comfortable in the 500ml per hour mark in average Irish temperatures.

I watch and calculate it carefully as dehydration will often lead to GI distress first due to an over concentration of glucose in the gut. This is usually the first sign. I know we’re told to watch for headache, cramping, etc., but I bet you’ve felt mild-moderate gut disturbance long before that.

One of the reasons we use so much homemade food is that it naturally holds more water content. Look at one of our average plumb date squares and then a CLIF bar. Homemade foods add to hydration, pre-packed foods tend to subtract.

In longer races and this one qualifies I’ll be doing the usual bodyweight check to assess hydration changes. Simple. Effective.

Electrolytes – I never worry about it because TRIFUEL has significant amounts of all 5 electrolytes. Again because we don’t really experience high temperatures in Ireland I am not anticipating an extreme loss through sweat. TRIFUEL should see us though just fine. I do carry extra electrolyte capsules just in case.

I really thought I could write a short blog on this but alas my passion for performance nutrition took over…again…

Interested in performance nutrition coaching? Check me out or email me Jill@teamjoebarr.com