EFS Drink Mix

$34.99 USD

NEW FOR 2024!

Our award winning EFS mix has been redesigned to help you train and race like never before.  With a scientifically validated 2:1 glucose: fructose ratio of carbohydrates, the new EFS formula stands at the forefront of carbohydrate fueling.  The lightly flavored, isotonic formula delivers a clinically effective dose of all 5 electrolytes (sodium, potassium, chloride, calcium, magnesium) in the levels shown to prevent cramping and keep you hydrated.

✓30g Carbohydrates
✓ Clinically effective dose of 5 electrolytes to prevent cramping
✓ Streamlined Formula for Faster Uptake




The all-new, scientifically formulated EFS is engineered to maximize performance by delivering a precise combination of Multiple Transportable Carbohydrates (MTC’s) so you can consume more carbohydrates without GI distress.

It's so effective, you’ll notice the difference first time you use it.

"When you nail your fueling it's pretty remarkable to see that you can actually get stronger as the race unfolds."
Hannah Otto

8th Place Unbound (2024)



Unlike most drink mixes, EFS delivers a clinically effective dose of all 5 electrolytes (sodium, potassium, chloride, calcium, magnesium) in the levels shown to prevent cramping.

Total electrolyte content (Na, Ca, Mg, Cl, K+) in mg
Based on 1 serving (12/23)


“The latest EFS formula is a breakthrough in fueling and hydration. With more carbs and electrolytes than competitors, you’ll finish the race as strong as you started.”

Phil Gaimon (2x World Hillclimb Champion)

Pro Tip: For best results have a serving of EFS 30 minutes prior to training and racing.

Rapid rehydration


We spared no expense upgrading the EFS drink mix, investing in the latest research-driven innovation and technology. Our scienficially formulated, isotonic formula quickly replaces the fluid and electrolytes lost during exercise to ensure optimal hydration, preventing the onset of fatigue, and improving peak performance.



Beyond simply enhancing exercise performance, EFS helps you improve endurance, go faster, and gives you the confidence to conquer the most daunting distances.


Delivers immediate & sustained energy-for peak performance

Prevents cramping and dehydration—delivers 1175mg of electrolytes

Ideal carbohydrate ratio-for immediate and sustained fuel

7% osmolality ensures bioavailability and reduces GI distress

Citric and malic acids promote oxygen uptake and energy production

New taste profile eliminates the flavor vs function compromise


EFS provides everything you need to maximize endurance and performance. Our industry-leading electrolyte levels help you stay hydrated and avoid cramping.

With the latest amino acid technology and ideal carbohydrate sources, EFS refuels working muscles faster than ever. Plus, the new flavor technology eliminates the formula over flavor compromise.

With EFS, you can train and race with confidence knowing you don’t have to worry about gaps in your nutrition.

"Beyond the increase in carbs/serving, I think the new flavors are the biggest advancement."
Jeffrey Rocco, MD


EFS is for use during exercise to prevent cramps, maintain fuel levels, and support mental toughness when it’s needed most. It can be supplemented with Liquid Shots before and during an event, and Ultragen helps consolidate gains during recovery between sessions. 

Regardless of your training load, a daily dose of our MultiV and Optygen lines help you lay a foundation to achieve your goals.

"On-the-bike taste was great. I felt amazing on the bike today! I had a PR on the top half of the climb. Surprised by this, because I had skied hard the day before."
Doug Davis

Cat I Cyclist


From the carbohydrates (osmotically balanced with your body in a 7% solution) to the electrolytes (20-100% better absorption rates), every ingredient in EFS is selected and portioned for faster and easier absorption without GI distress.

The inclusion of citric acid encourages oxygen uptake and production of ATP (the body’s energy source), helping your cells use the fuel once it’s delivered.


Delivering nutrients means nothing if your body can’t sign for the package, so we sourced every ingredient for purity and bioavailability.The carbs’ low osmolality provides superior fluid absorption and reduces GI distress.

We also omit ingredients with no value—even the ubiquitous vitamin C, which features in virtually every other mix despite research that shows it reduces endurance when taken during exercise.


Our approach to product design eschews unexamined ingredients, traditional processes, and trendy minimalism in favor of research-based innovation, premium ingredient sourcing, and the uncompromising expectations of elite athletes. We’re always ready to show our work and support our products with the scientific literature that informs our design choices, but we also know what virtually every athlete and publication using or reviewing our products learns firsthand: First Endurance products speak for themselves, and you can feel the difference right away.


30 servings per container

Serving size one scoop (35g)

Amount per serving

Calories 120

% Daily Value•

Total Fat Og


Saturated Fat Og


Trans Fat Og

Cholesterol 0mg


Sodium 300mg


Total Carbohydrate 30g


Dietary Fiber Og


Total Sugars 25g

Includes 25g Added Sugars


Protein Og

Vitamin D Omcg


Calcium 100mg


Iron 0mg


Potassium 160mg


Magnesium 150mg


Chloride 465mg


*The % Daily Value tells you how much a nutrient in a serving of food contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.

INGREDIENTS: Cane Sugar, Dextrose, L-Glutamine, Citric Acid, Maltodextrin, Salt, Dimagnesium Malate, Dipotassium Phosphate, Dicalcium Malate, Natural Flavor.


Q:What are the main differences between this formula and the prior version?

A: The new EFS delivers more carbs and electrolytes (possible because of new technology), no longer contains Suntheanine (because of athlete & customer requests), or BCAA's (the latest research shows they can delay carb absorption and digestion). We also reduced the flavor and sweetness (because of athlete & customer requests).

Q: How is EFS different than EFS-PRO?

 A: Though EFS is itself a step above the competition, EFS-PRO supports the most demanding efforts in the most extreme conditions by providing 2x more carbs and more electrolytes/serving. 

Q: Are there other benefits to drinking EFS or EFS-PRO, besides for training and racing?

A: Absolutely. EFS and EFS-PRO can be used to top off glycogen and electrolyte levels before an event or race.

 Q: Is EFS gluten free?

A: Yes, EFS and EFS-PRO are both gluten free.

 Q: Do EFS or EFS-PRO have any artificial flavors or colors?

A: No, but it tastes so good you’d be forgiven for thinking we were cheating.

 Q: Do I need to take a full serving of EFS or EFS-PRO to get a benefit? 

A: No. A higher concentration increases calories and electrolytes. In other words, if you are a smaller person and normally consume a somewhat reduced amount, you will still get the same benefits.

 Q: How much EFS should I use during my training and racing?

 A: For best results, have one serving 30 minutes before exercise & use as needed during exercise. Additional calories and electrolytes can be added with Liquid Shots.

Q: Is EFS vegan friendly?
A: Yes.

Q: What's the glucose:frucose ratio in the formula?

A: The glucose: fructose ratio in the EFS formula is  2:1 Glc:Fru.

Q: Does EFS or EFS-PRO help me hydrate better than water?

A: We won’t name them, but there’s a growing list of competitors in the sports hydration game making the claim that their product hydrates better or faster than water alone. This is a so-what claim predicated on evidence that not only doesn’t apply to endurance athletics, but actually hampers performance during long-term endurance events. For their rationale and claims support these companies cite WHO and other medical guidelines for treating serious dehydration in disease and severe exposure conditions, not the sports nutrition guidelines for healthy athletes in endurance competitions. Also important is the need for more fuel, and these drinks fall short in the fuel department. Check out Dr. Bucci’s extended consideration of these claims here.

 Q: I’ve heard that there are benefits to having protein during exercise. Why doesn’t EFS contain protein?

A: EFS contains 2g of the free form amino acid glutamine per serving which is the equivalent of 9g whey protein. Protein naturally contains glutamine.

Clinical evidence supporting the use of glutamine during exercise dates back to 1991. These clinical studies clearly indicate supplementing with as little as 1g free form amino acids improved performance, reduced post-exercise muscle damage, improved muscle glycogen resynthesis, reduced central fatigue and improved rate of perceived exertion. These are the same claims made by the most recent protein study and clearly support a mechanism for improved performance.

In addition to the clinical support, other factors lead to a decision to use these free form amino acids over complete proteins.

Proteins are more difficult to digest than amino acids during exercise, they don’t taste very good during exercise, and they can reduce the glycemic index of a drink, further reducing its ability to be quickly absorbed. There is considerably more evidence supporting free form amino acids than complete protein

 Q: Are EFS and EFS-PRO safe for kids?

Yes. Just make sure they pay it back during their turns at the front. 

 Q: I am prone to cramping during longer training and racing. Will EFS help me with cramping and dehydration problems?

A: Yes, cramping stems from electrolyte imbalance, electrolyte depletion and/or dehydration. EFS provides a clinically-effective dose (of all 5 key electrolytes) to prevent cramping and dehydration. The combination of all five electrolytes delivers a potent 1175 mg per serving, helping to prevent cramping. The 300mg sodium per serving also aids in maximum fluid absorption so you stay hydrated throughout your training and racing. Supplementing with additional salt tabs, electrolyte tabs, or salty snacks is not necessary with EFS.