Updated for 2024

Summarizing the critical differences between the two formulas.


We recently updated the formulas for the EFS and EFS-PRO hydration mixes, streamlining them to dial the focus on what really counts: fueling, hydration, and cramp prevention. In other blogs, you can learn about how EFS and EFS-PRO provide scalable, osmotically balanced, GI-friendly carbs and far outpace the competition with a full suite of all five electrolytes to prevent – not just alleviate – cramping.

But here, we’re explaining the differences between the two formulas themselves, listing the ways that EFS-PRO represents an upgrade over standard EFS and helping you identify when EFS will suffice or when extreme conditions warrant the extreme performance of EFS-PRO.


  • 1,160mg of all five electrolytes (sodium, potassium, calcium, chloride, and magnesium)
  • 30g of carbs (maltodextrin, glucose, and sucrose)
  • Osmotically balanced with multiple carb sources
  • Palatable flavor profile for multi-hour intake
  • Use for exercise lasting under three hours and/or temperatures below 85F

EFS isn’t EFS-PRO, but its carb delivery and electrolyte count are competitive with – or simply outpace – every other endurance hydration mix. If EFS were produced by any other company, it’d be the “PRO” version. It combines three carb sources with a huge load of electrolytes in a formula tailored by research and refined through real-world testing.

The best conditions for EFS are about time and output – for training sessions or races under three hours or for longer days at low intensity, EFS is plenty.


  • 1,400mg of all five electrolytes (sodium, potassium, calcium, chloride, and magnesium)
  • 60-120g of scalable carbs (cyclic cluster dextrin and sucrose)
  • Faster stomach emptying, scalability, and proven performance benefits
  • Minimalist flavor for unlimited, all-day palatability
  • Use for exercise lasting over three hours and/or temperatures above 85F

EFS-PRO was engineered for professional athletes – that “PRO” appellation isn’t just marketing hype. If you’re pushing high intensity output for longer than three hours, you want to scale carbs above 60g per hour, or temperatures are above85F, then we recommend EFS-PRO.  It’s also perfect for athletes who have sensative stomachs.

The scalability of EFS-PRO’s primary carb source – CCD – means the concentration can be ramped up to match the hardest days in the hottest conditions; but even at its basic concentration, EFS-PRO delivers more Gi-friendly carbs and cramp-preventing electrolytes than any other formula. Period.


That covers the overview of both formulas, but here are two more things to keep in mind while planning your fueling and hydration strategy: the source of the carbs and the flavor of the mix itself. Given its PRO status, it’s not surprising that EFS-PRO does have an edge in both categories.


If you’re leaning towards EFS-PRO, it’s probably because of cyclic cluster dextrin, the key to EFS-PRO’s ability to jump up to 100+ grams of carbs per hour. Your gut loves it, and it has also been shown in clinical studies to actually improve performance beyond simply providing fuel – CCD really does change the CHO game.

Athletes with sensitive stomachs who want to hit triple-digit CHO intakes may also experience better results with EFS-PRO, because CCD is isotonically aligned with your body’s internal chemistry. It doesn’t overload the osmotic balance in your GI tract, even when mixed at double or triple concentration, and CCD’s characteristics help eliminate the need to train your gut for higher carb loads.


Both of the revised formulas have lighter flavor footprints, because a hydration mix is only useful if you can keep drinking it for as long as you need it, and flavor fatigue over three, five, or 12 hours is a real obstacle.

For those who prefer a minimal palate profile, EFS-PRO High Carb has a lighter, refreshing taste that doesn’t linger with cloying sweetness or beat you over the head with obnoxiously overstated flavors in order to mask electrolyte content. EFS isn’t overly sweet by any means, but its flavor is slightly more pronounced than EFS-PRO – that may be a critical consideration for longer events.


Chances are good, the answer to that question is: Both.

The defining difference between EFS and EFS-PRO is largely one of scale, with EFS-PRO blowing the lid off of electrolyte levels and hourly carb limits. Depending on the day’s demands, EFS may carry all of the carbs and electrolytes you need. On those longer, harder, hotter days, you may need the electrolyte boost and scalable, performance-enhancing carbs of EFS-PRO.

May 23, 2024 — First Endurance


Jeff said:

This post is very timely for First Endurance users. As a shorter distance triathlete (Olympic) I was struggling to understand how to determine when you needed EFS vs EFS Pro with the new formualtions (hydration + fueling) after being a former EFS Pro loyalist focused on hydration due to sweat loss. I was not sure about the high calorie count in the new EFS Pro formulation and was not sure about diluting the mix. I tried the new EFS formulation and was struck upside the head by its sweatness, …not good. My dilema now was what is First Endurance's solution for me? Not to fear, as is true with First Endurance, they must have listened to other athletes and produced the answer with their new EFS. I recently received their new Lemon-Lime EFS formulation and was told it would solve my dilema. True to the company's commitment to athletes it did. Balanced sweetness, all the hydration elements I trust from experience, and fueling in line with the original EFS Pro. Bullseye! EFS will be my new 'go to' formula for 2024 race season and beyond. Thx First Endurance!
Jeff Gordon, 2023 USAT Age Group M55-59 Olympic Distance National Champion

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