More carbs, a streamlined formula, and increased performance

By Luke R. Bucci, PhD CCN CNS

EFS has been leading the industry for endurance fueling for almost two decades, breaking the electrolyte, flavor fatigue, and GI tolerability barriers – and then adding upgrades to keep your head in the game. It’s time for EFS to leap ahead yet again, taking advantage of recent clinical research and real-world practices on ever-increasing carb intakes to capitalize on what really works in the field.

The reformulation of EFS has been drastic – drastically good! It’s streamlined with fewer ingredients. The triple carbs (sucrose, glucose, and maltodextrin) are the same ones, but the ratios have changed to take advantage of fructose benefits without its downsides. There are also more carbs per serving, and the amount of carbs is rounded off to 30g, making it easier to calculate your specific carb intake goals to reach 60, 90, or 120 grams per hour – just add more scoops. Also returning is the same total amino acid amount, 2,000mg. We also didn’t tamper with the electrolyte contents – they’re as high as ever.

Key omissions include Stevia, monk fruit, or artificial sweeteners. 

As usual, the new formula is all based on clinical human research and science, and even more importantly, the prototypes were worked out in field testing by top athletes, covering all the real-life factors that make a winning formula, not just a formula that looks good on paper.

More Carbs, More Fructose

EFS has always had fructose – but not free fructose – as one half of the sucrose molecule (sugar – it’s just glucose and fructose). With increased performance demands for longer, more brutal events, hourly carb intakes have dramatically increased from 30-60 to 60-120 grams per hour, with good tolerability, with weeks of gut training. With increased carbs per hour, performances have improved, and recovery is easier.

EFS still utilizes sucrose to increase fructose intakes, which increases carbs per hour by opening a backdoor delivery avenue. Because of the known long-term downsides of fructose, sucrose is the best delivery vehicle for fructose itself without having to deal with free fructose issues. Forgotten human studies have shown that sucrose – by itself – is as good as (and usually better than) 1:1 ratios of glucose:fructose or pure fructose itself. No GI side effects and even better performance. So we upped the sucrose as the main carb in EFS, which has the added benefit of solving other factors important to keep taking EFS for the entire length of endurance and ultra-endurance events – taste fatigue and making electrolytes tasty.

Glucose and maltodextrin are still in the carb mix, so EFS is MTC – Multiple Transportable Carbohydrates. Those GLUT5 receptors ares still upregulated by the 2:1 Glucose:Fructose ratio in EFS, and following the research, additional fructose works best when glucose transport into the gut is maxed out. EFS accomplishes this by keeping enough maltodextrin and glucose to maintain excellent stomach emptying with less stomach feelings of fullness, so that in effect, the sucrose becomes a 1:1 Glc:Fru bomb. The GI tract has enormous capacity to split sucrose into free fructose and glucose (sucrase enzymes), right on the surface of absorptive endothelial cells. To your gut, it sees the same carbs as if you ingested 1:1 Glc:Fru. And after glucose is loaded, that carb bomb tops off glycogen for later use when needed most.

“It is concluded that in the healthy state the absorption capacity of fructose given alone ranges from less than 5g to more than 50g. The absorption capacity of fructose given as sucrose is much higher. Glucose stimulates fructose uptake in a dose dependent fashion.” (Rumessen Gut 1986; p.1161).


The Fructose Backstory

Why are we down on free fructose? First of all, it delays stomach emptying and is less well tolerated – important real-life issues for endurance training. This makes gut training easier, and race days, too.

Second, fructose has a long-term dark side that most people will not worry about because those problems are in the future. Simply put, any fructose that is not immediately absorbed or that piles up in the bloodstream will react with proteins, called glycation, forming non-self targets for your immune system. That’s a low incidence event, but it does add up over time into one of the more important causes of aging and worse, like your body silently rusting and amping up overall inflammation. While not noticed or felt during racing, it adds up over time and you’ll feel it later.

If you care about your health, you’ll care about keeping free fructose under certain limits – limits that are breached with the current high-fructose products. Just look at what’s happened to high fructose corn syrup (basically a 1:1 free Glc:Fru carb source). HFCS is the current champion of the what’s-bad-for-you of current diets. So is excess sugar, but for couch potatoes getting too much carbs without burning them for exercise performance, sugar is over-consumed, and that free fructose swamps the liver and enters the bloodstream.

During serious, long-term exercise, free fructose from sucrose is converted to glucose in the gut cells themselves, and any fructose escaping the gut gets sucked up by the liver and converted to glucose and glycogen (or fatty acids) and does not get into the bloodstream. Couch potatoes are maxxing out lazy livers’ ability to get rid of fructose fast enough, and the resulting free fructose in the bloodstream happens, with all its known evils.

Flavor Matters

Taste has been tweaked to not be overwhelming, cloying, or obnoxious during longer exercise sessions, because if you don’t drink it, it can’t help performance. Feedback from top athletes guided the best, most practical (and actually enjoyable) flavor/sweetness profiles, from pre-race to the final kick. One less thing to worry about so you can keep up and adapt your race strategy.

More Carbs, Less Belly Ache

The new EFS fuels bigger carb intakes during an event, bringing more than just superior exercise performance – faster pace, faster times, longer distances. In the 100-mile ultramarathon, faster runners consumed more carbs and maintained their blood glucose (meaning less lactate buildup and less glycogen depletion). Second, less GI issues during a race indicate you’re getting more glucose to your working muscles and brain. Third, you feel better and are not as wiped out after a grueling event. (Arribalzaga 2021; Berger 2023; Inamura 2024; Martinez 2023; Ryan 2023).


Arribalzaga S, Viribay A, Calleja-González J, Fernández-Lázaro D, Castañeda-Babarro A, Mielgo-Ayuso J. Relationship of carbohydrate intake during a single-stage one-day ultra-trail race with fatigue outcomes and gastrointestinal problems: A systematic review. Int J Environ Res Public Health. 2021 May27;18(11):5737.

Berger NJ, Best R, Best AW, Lane AM, Millet GY, Barwood M, Marcora S, Wilson P, Bearden S. Limits of Ultra: Towards an Interdisciplinary Understanding of Ultra-Endurance Running Performance. Sports Med. 2023 Sep26:1-21.

Inamura N, Taniguchi H, Yoshida S, Nishioka M, Ishihara K. A comparative observational study of carbohydrate intake and continuous blood glucose levels in relation to performance in ultramarathon. Sci Rep. 2024 Jan11;14(1):1089.

Martinez IG, Mika AS, Biesiekierski JR, Costa RJ. The Effect of Gut-Training and Feeding-Challenge on Markers of Gastrointestinal Status in Response to Endurance Exercise: A Systematic Literature Review. Sports Med. 2023 Apr 15:1-26.

Rumessen JJ, Gudmand-Hoyer E. Absorption capacity of fructose in healthy adults. Comparison with sucrose and its constituent monosaccharides. Gut. 1986;27:1161-8.

Ryan T, Daly E, Ryan L. Exploring the Nutrition Strategies Employed by Ultra-Endurance Athletes to Alleviate Exercise-Induced Gastrointestinal Symptoms—A Systematic Review. Nutrients. 2023 Oct11;15(20):4330.

May 21, 2024 — Luke Bucci

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