You can eat exactly the right amount of carbohydrate and still run out of energy. Not because the number was wrong, but because the format made delivery slow, uncomfortable, or unreliable at the worst possible moment.
Most athletes treat mid-race fueling as a math problem. Hit 60 to 90 grams of carbohydrate per hour, job done. But that equation ignores a critical variable: how those carbohydrates move from your gut into your bloodstream, and how the format you choose either accelerates or stalls that process. This post breaks down the physiology of energy delivery, what actually limits absorption during exercise, and what it means practically for how you fuel.
What Happens to a Gel After You Swallow It?
Your gel follows a specific absorption pathway before a single gram reaches your working muscles. First it enters the stomach, where it must begin mixing with fluid before the stomach can pass it forward. Then it moves into the small intestine, where two primary transporters, SGLT1 and GLUT5, pull glucose and fructose across the gut wall and into the bloodstream. Only then does it become fuel.
Every stage in that chain is a potential bottleneck. And the format of your energy source determines how quickly each stage completes. A thick, high-viscosity gel sits heavily in the stomach and resists emptying, especially at high intensity when blood is actively redirected away from the digestive system. The result is the sensation most experienced athletes recognise: that heavy, sloshing feeling in the chest at kilometer 30 that no amount of willpower resolves.
Research on gastric emptying consistently shows that fluids empty faster than semi-solids, that lower osmolality solutions move through faster than hypertonic ones, and that high exercise intensity slows emptying across all formats. The gel format itself is working against you if the viscosity is high.
Why Does Gel Concentration Cause Stomach Problems?
The concentration of a carbohydrate solution, measured as osmolality, directly determines what your gut does with water. Hypertonic solutions, meaning those with a higher solute concentration than your body fluids, pull water into the gut lumen to dilute themselves. That process is associated with bloating, cramping, and in severe cases, diarrhea.
Most traditional gel sachets are highly hypertonic. This is precisely why manufacturers instruct athletes to chase them with water. The logic is sound in theory. In race conditions, timing a water station perfectly to coincide with a gel is rarely clean. Miss the window and the concentrated bolus sits in your gut drawing fluid in rather than delivering energy out.
Isotonic solutions, formulated to match the osmolality of body fluids, move through the gut with significantly less disruption. They do not require additional water to function. For athletes competing at intensities where the gut is already under stress, this is not a minor detail when considering how different formats behave physiologically.
Does Taking Smaller Amounts More Frequently Actually Help?
Yes, and the mechanism is straightforward. The stomach empties more efficiently when intake is smaller and more frequent rather than delivered in large single boluses. An athlete consuming one large gel every 45 minutes creates a repeated high-concentration hit that the stomach must process all at once, with gastric emptying slowing at the peak of each bolus.
The same total carbohydrate consumed in smaller doses every 15 to 20 minutes creates a more consistent, lower-concentration flow through the gut. Emptying is more predictable, absorption is steadier, and the risk of gut distress is reduced. This is not just anecdotal. It aligns with established sports nutrition guidance on carbohydrate dosing frequency during prolonged exercise.
The format of your fuel shapes how easy it is to dose this way. A 40ml fluid gel is far more suited to frequent small intake than a thick sachet that requires effort to consume and time to settle.
Frequently Asked Questions
Why do I feel nauseous after taking gels during a race?
Nausea after gels is most often associated with high viscosity or high osmolality, the two properties that slow gastric emptying and draw water into the gut. At race intensity, blood flow to the digestive system is already reduced, which compounds the effect. Switching to a lower-viscosity gel and experimenting with smaller, more frequent doses is a commonly recommended strategy in sports nutrition practice.
Do I need to drink water with every gel?
With a hypertonic gel, water is generally recommended to help dilute the concentration and support emptying. With a gel formulated to isotonic osmolality, additional water is not required for gut function, though staying hydrated overall remains important for performance.
What is the difference between glucose and fructose in a sports gel?
Glucose is absorbed via SGLT1 transporters and fructose via GLUT5. Because they use separate pathways, combining them at a 2:1 ratio allows the gut to absorb more carbohydrate per hour than glucose alone. Independent research by Jeukendrup and colleagues, conducted without involvement of SUPPLME or its products, demonstrated that this dual-transporter approach increases total oxidation rates to around 90 grams per hour versus approximately 60 grams per hour from glucose alone.
How does liposomal technology work in sports supplements?
Liposomes are microscopic phospholipid spheres that encapsulate active compounds. Structurally, they mirror human cell membranes. In research settings, this structural similarity has been studied for its role in protecting encapsulated compounds from degradation in the digestive environment and facilitating their passage across cell membranes. This is an active area of scientific investigation in nutrition and pharmacology.
What Should You Actually Do?
Audit your current fueling format before you audit your gram totals. Check whether your gel is thick and hypertonic. If it requires water to function properly, consider whether you are reliably delivering that in race conditions. Move toward smaller, more frequent doses rather than large boluses. And choose a format with low viscosity and appropriate osmolality so the gut is not working against you at the moments you need it most.
Science over hype. Every time.
The physiology outlined above informed the design intent behind the SUPPLME Liquid Energy Gel, a supplement in a 40ml ultra-fluid format built on a 2:1 glucose-to-fructose ratio delivering 32 grams of carbohydrate. It is formulated with osmolality in mind, incorporates liposomal delivery technology, and requires no water or preparation to use.
References
Jeukendrup, A.E., Moseley, L., Mainwaring, G.I., Samuels, S., Perry, S., and Mann, C.H. (2006). Exogenous carbohydrate oxidation during ultraendurance exercise. Journal of Applied Physiology, 100(4), pp.1134-1141. Independent research. No involvement of SUPPLME or its products.
Jeukendrup, A.E. and Chambers, E.S. (2010). Oral carbohydrate sensing and exercise performance. Current Opinion in Clinical Nutrition and Metabolic Care, 13(4), pp.447-451. Independent research. No involvement of SUPPLME or its products.
Leiper, J.B. (2015). Fate of ingested fluids: factors affecting gastric emptying and intestinal absorption of beverages in humans. Nutrition Reviews, 73(S2), pp.57-72. Independent research. No involvement of SUPPLME or its products.
