This is an extended A for a Q&A in response to a tendency for some hydration mix companies to make spurious claims about how their products hydrate faster than or better than water. In this extended Q&A, Dr. Luke R. Bucci explains why the science behind those claims doesn’t apply to endurance athletics.

Q: Does EFS help me hydrate better than water?

A: That’s complicated. 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 and/or faster than water alone. This claim is not only misleading, it’s also predicated on evidence that not only doesn’t apply to endurance athletics, but actually hampers performance during endurance events and can even contribute to deleterious tissue damage.

There are three aspects to a traditional endurance hydration mix: supplying fuel, replenishing electrolytes, and—of course—hydrating a body at work. The “hydrates better than water” claim is usually proffered by companies who focus almost exclusively on hydration with a lesser focus on electrolytes and a minimal focus on fueling. They base their formulations on World Health Organization (WHO) guidelines for hydration therapies on sick people—mostly children with severe diarrhea—being treated in medical settings.

The WHO’s recommendations are, of course, not applicable to healthy adults exercising, which has very different implications than serious dehydration caused by medical conditions and diseases. The “science” and/or “research” data informing these claims is contrived to inflate success for their products or formulas by using unrealistic comparators (i.e., no hydration, only water, IV rehydration)—again, this is a highly misleading and irrelevant comparison for endurance athletics, largely because it ignores the context in which the mix is being used and the need for carbs as fuel.

The mixes based on medical dehydration guidelines instead of endurance exercise guidelines do promote faster water and electrolyte uptake, but they don’t support faster glycogen recovery with their measly carb allotment. The universally accepted guidelines covering carbohydrates during long-term exercise are a lot higher than what these hydration-only companies are advocating, making them uniquely unsuited for endurance athletics. You’ll be hydrated but you’ll bonk.

These companies tout their mixes’ very low carbohydrate content because it produces a lower osmolality in your stomach, which in turn means faster absorption of water and electrolytes. This is true, but it’s also a technicality, and—per the discussion of carbs above—it’s definitely NOT what long-term endurance athletes want and need. For endurance athletics, not bonking is as important as staying hydrated and replenishing electrolytes, but these mixes only address hydration and electrolytes. You’re on your own for fuel.

By using the WHO’s medical recommendations, these companies are carefully selecting for evidence that ignores and deflects the need for carbs during long-term exercise in order to support their hydration claims. When describing their products’ recommendations for use, they tend to include a “food-in-pocket” clause to explain why they omit adequate carbs. That’s a tacit admission that these hydration mixes aren’t actually equipped to do what endurance athletics require, which isn’t a surprise once you realize—like explained above—that these mixes are essentially made for children suffering terminal dehydration due to medical conditions, not for healthy endurance athletes.

The food-in-pocket clause conceals another realization: if an endurance athlete is carrying food, then they do not need a hydration drink—they can simply use water. Proper endurance hydration mixes like EFS or EFS-PRO lessen or negate the need to carry food because they include enough carbs to keep you going on their own. Instead of food-in-pocket, First Endurance gives you food-in-bottle.

The food-in-pocket clause also ignores the real-life problems with carrying solid food during endurance athletics: inconvenience, eating too much or too little, having to defecate during an event, carrying excess weight, time wasted, distracting from performance, and the risk of GI issues that actually defeat the intent and function of hydration drinks!

To expand on that last point, these hydration-first mixes’ only advantage is fewer carbs which means a lower osmolality in your stomach which means faster absorption of water; however, the food-in-pocket clause negates that. Ingesting food-in-pocket calories resets osmolality in your stomach, because the hydration mixes and the solid food are processed in the same place (your stomach), so the low osmolality of the hydration mix becomes much higher because of the sandwich or cookies that you’re consuming for fuel, reducing the speed and ease of uptake for electrolyte, carbs, and water. In fact, chances are very good the combination of solid food and these hydration mixes will net an osmolality much higher than EFS or EFS-PRO’s relatively low 7%, making hydration and electrolyte uptake actually slower for these products when used in an endurance setting that requires constant hydration and calorie intake.

Further, if you ignore the food-in-pocket clause and use the hydration-only mixes on their own, you’ll even be risking damage to muscle and connective tissues. Low carb supply during exhaustive, long-term exercise is associated with increased free radicals, which uncouple mitochondria from making energy (ATP). That leads to microtrauma in muscle fibers that manifests as DOMS. Burning more fat than carbs also generates more free radicals in mitochondria (in muscles)—this happens when carbs run low, and it creates a further risk of tissue damage.

In the end, we combine hydration, electrolyte replenishment, and fueling through carb intake in EFS and EFS-PRO because it remains the simplest, most effective solution to covering an athlete’s needs during extended endurance events or training sessions.