You spoke. We listened. The ultimate high-carb fueling platform is born.


Carbs have always been king in endurance athletics, and that’s more true now than it’s ever been. Working with athletes we sponsor directly (and pros with other sponsors who still clandestinely use the FE system), we hear a LOT about carbs.

The group includes WorldTour pros, LifeTime privateers, IRONMAN champions, Olympians – the most demanding group of endurance athletes you can imagine. And their top demand? Lifting the ceiling on carb intake. 90g per hour, 120g – sometimes even 130g. Or more. They wanted us to develop a tool that would erase carb limits.

So we did.

The all-new EFS-PRO is engineered and tested to deliver 60g, 90g, or even 120g of liquid carbs in a single bottle. (Yeah, you read that right: 120g of CHO.) It’s virtually limitless fueling, able to scale up as much as you need it to for the hardest days and the biggest races. If a given day is circled in red on your calendar, then EFS-PRO is made for it.

What the pros said

Here’s a sampling of the feedback we got. We’ll keep it anonymous, because some of our collaborators are long-time FE enthusiasts with conflicting sponsor obligations to maintain. (If that’s you, don’t worry – your secret’s safe with us.)

“If it’s a really hard training day or race, I target 120g+ of carbs per hour.”

“I target 120-130g per hour on big fueling days.”

“Depending on intensity, I target 80-120g of carbs per hour.”

We also gleaned a critical preference: getting at least half of those carbs from a hydration mix, which is more convenient when an athlete’s at threshold and choking down solid food isn’t ideal.

“I try to get about 1/3 to 1/2 of my carbs from drink mix and the rest from gels or bars.”

“The more and more races I do in gravel, the harder and harder it is to eat food vs. drinking.”

“Taking in half of my carbs from mix and half from other sources would be ideal.”

So for those keeping score, that’s triple digits of CHO, at least half of which needs to be from the bottle.

Traditionally, that’s impossible. Bellyache city, followed by a calamitous, messy DNF. But we’re not into tradition – we’re into technology and breaking barriers. So breaking the carb ceiling was no problem, and the new EFS-PRO pushes the limit out to 120 liquid grams per hour, leaving plenty of room to supplement with solid fuel.

Here’s why (and a little bit of how) we did it.

What the research says

So of course this is where we started. Pros told us what they wanted, and we did the legwork to figure out how to do it. It turns out that the carb craze also happens to align with recent research, which has pushed target carb intake levels for endurance athletes from 30-60g per hour up to those lofty numbers so many of our guinea pigs – err, professional athletes cited.

The biggest concern with big carb loads is, of course, GI distress, so we created a belly-friendly, isotonically balanced solution that can double or triple in concentration without punching you in the gut.

A secondary (but still important) concern? Flavor. Fuel does no good if you literally can’t stomach it, and high-performance carb/electrolyte mixes need to be palatable for three+ hours or they aren’t worth their salt.

In response to this and other feedback we’ve received from you, we engineered a new electrolyte and fuel system formulated for professionals – an EFS-PRO, if you will – that delivers huge carbs with less GI distress and a light, unobtrusive flavor. It’s also got all five electrolytes for industry-leading, clinically studied cramp prevention, and it’s finished with… 

Nothing else. A minimalistic formula engineered for pure performance.

The ultimate performance carbohydrates

Brass tacks time. The carb mix is a 50/50 split of highly branched cyclic cluster dextrin (CCD) and sucrose – all told, it’s effectively a 6:1 ratio of glucose to fructose that unlocks every possible avenue for feeding glucose into your cellular ATP threshers.

When it comes to delivering CHO, CCD is the premier form of carbs for endurance performance. Its unique molecular structure absorbs into your GI tract without brick-in-the-belly side effects and your body breaks it down easily into glucose to feed the ATP cycle. It can also be mixed at high concentrations – up to double – and still not blow up your gut. It digests faster, it’s easier on overworked GI tracts, and it boosts uptake of other critical performance nutrients like electrolytes.

Many of our testers also had questions about fructose, which can be sticky for exercise, but we unlock its potential by using sucrose (which contains one glucose and one fructose molecule).

Here’s the extremely short version: When conditions and administration are correct, fructose is an effective way to sneak more glucose into your system through a dedicated backdoor receptor. Once there, your body turns it into glucose – but only if your system is also saturated with glucose to begin with. Since every fructose you’re ingesting is paired with a glucose (sucrose = glucose + fructose), and you’re turbo-loading glucose with CCD, then the conditions are correct.

Here are some of your notes on carbs:

“Personally, I have found that glucose and sucrose seem to work best on my stomach.”

“I’m a fan of cluster dextrin – the formulation that you have in EFS-PRO is amazing!”

“I don’t have a strong preference, as long as there is a good blend to prevent carbohydrate fatigue in the gut.”

Industry-leading cramp prevention

Electrolyte content is one area where our testers surprised us, responding with, essentially, a lot of shrugs. But don’t worry – that’s why we’ve got resident sci-guy Dr. Luke Bucci!

Carbs are all the rage, for good reason, but electrolytes are critical for preventing cramps, especially in the high heat and extreme efforts of summer A races. By including all five electrolytes instead of just sodium and potassium, EFS-PRO takes advantage of every avenue for electrolyte absorption.

While all five electrolytes are important, we’re sliding magnesium into the spotlight. Even though it’s literally medical-grade cramp prevention, it’s largely overlooked by the endurance supplement industry for exercise applications. But not by Dr. Bucci, who always insists that we emphasize the point: including all five electrolytes – especially the clinically studied magnesium – isn’t just a way to treat cramps; it’s a way to prevent them altogether.

Here’s a sampling of the mixed bag of responses about electrolytes and cramping:

“I don’t really know much about electrolytes.”

“I don’t feel like I have enough knowledge on electrolytes to have an opinion.”

“Electrolytes have become one of the most forgotten conversations as carbs have come to the forefront.”

“Honestly, this isn’t something I watch closely.”

“I know when I’m bonking, but lack of electrolytes seems harder to diagnose on any given ride.”

“According to my sweat test, I target consuming 500 - 600mg of sodium.”

“I focus on taking in 500 - 800mg of sodium per hour.”

Limitless scalability

This is what CCD unlocks. A standard serving provides 60g of carbs, so you can take a bottle of mix, a bottle of water, and supplement with Liquid Shots or something like toaster pastries or peanut candy every hour. But we didn’t stop there, because many of the athletes we work with want a higher percentage of carbs to be from GI-friendly, easily consumed hydration mix. The magic of CCDs makes it so.

Go ahead, double the concentration. Each bottle can scale up to become a 120g warhead of superlative CHO fueling – and since it’s so easy on the belly, there’s no need to “train” your gut before leveling up your carb intake.

“I like to carry between 60-100g of carbs in a single bottle for hard training days.”

“I’d prefer to run one bottle with all of the mix and one bottle of plain water.”

“I would like to see the ability to take in up to 60g of carbs from a drink mix with less sweetness so that it can be mixed stronger.”

Aggressively minimalist

One of our key takeaways from the responses we got throughout this process was that a hydration mix should be simple. Carbs. Electrolytes. Done.

In response, we’ve worked to evolve the First Endurance system so that performance-boosting additives like nootropics (caffeine, theobromine, etc.) can be supplied with supplemental pieces like PreRace or OptygenHP. That lets us keep the hydration mix as simple as possible, maintaining an isotonic solution and reducing the risk of high carbs leading to high alert in the GI tract.

“For anything outside of carbs and/or electrolytes, I’d like to use those on my own terms outside of a drink mix.”

“Less is more in a drink mix for me.”

“I’d like to see a product with fairly simple ingredients.”

Palatable for hours

We designed this mix for use in sessions and races that are longer than three hours, like the gravel epics that are beginning to define North American cycling, grand tour stages, and IRONMAN events. As mentioned above, it’s also designed to be mixed at double concentration for the most extreme carb targets.

That means it can’t be too sweet, so we gave it our lightest flavor yet – a subtly bright citrus profile that doesn’t fatigue your palate after hours of use or explode with cloying sweetness when mixed at higher concentrations. Like with running shoes or saddles, a hydration mix’s flavor is best when you don’t notice it at all.

“I prefer subtlety in both flavoring and sweetness.”

“Ideally, keep the sweetness low so that it can be mixed at a higher concentration for maximum CHO content.”

“I prefer my drink mix to be flavored, but I would prefer no flavor over too much flavor.”

“It is really important that the sweetness does not go up with increases in concentration.”

You speak. We’re still listening.

Whether you’re a pro, a privateer, or a recreational pursuer of PRs, we’re always dead serious when we ask for your feedback, because no one knows what elite athletes need more than elite athletes themselves. While engineering EFS-PRO, we combined that feedback with clinical studies on endurance performance. This is the result.

And it doesn’t end now. Keep sending us feedback, keep emailing your comments, keep telling us what we’re doing right – and, more importantly – where we can improve to better support your efforts.

Together, we’re making the best endurance nutrition in the world.

May 16, 2024 — First Endurance


Joseph said:

Will you be making this in Sour Watermelon flavor, please!!!

Michael said:

Thanks for taking the time to let us know what you think David. We’re honored to have you fuel with First Endurance!

David said:

Always Innovating great projects into better for athletes looking for the best from both themselves and these products the crew at FE puts out. I love the fact you provide the how, why and what in these releases, I believe it shows brains 🧠 and truthfulness in a market where that’s a rare commodity now days. Thanks for all your amazing support of me and in return I’m always going to support First Endurance Sports Nutrition Co. So looking forward to this new product.

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