You’ve probably heard this one: “Never take an energy gel with a sports drink — you’ll destroy your stomach.”

It sounds like settled science.

It isn’t.

What the myth gets right

An athlete who takes a concentrated gel and washes it down with a carbohydrate sports drink is delivering a large carbohydrate load to the stomach in a short window. Gastrointestinal complaints during endurance exercise are common, and the research literature identifies carbohydrate load and solution concentration among the contributing factors.^[1]

Work using gastric aspiration techniques found that the rate at which fluid leaves the stomach is strongly influenced by the carbohydrate energy content of what was swallowed. Concentrated carbohydrate solutions emptied considerably more slowly than dilute ones.^[2] So the anecdote behind the myth is usually a true report of a real event.

Where it goes wrong

The variable in that research is concentration and total carbohydrate load — not the act of combining two products. A gel taken with water plus a sports drink taken separately can arrive at the same carbohydrate concentration as a gel taken with a sports drink, depending entirely on quantities. The gut does not know which packaging the carbohydrate came from.

This matters practically, because the myth leads athletes to the wrong correction. The fix that actually follows from the evidence is simpler: pay attention to how much carbohydrate you are taking per hour, and how concentrated it is when it arrives.

Mixing may be part of the solution

Carbohydrate absorption in the small intestine is transporter-dependent, and the transporter handling glucose approaches saturation somewhere around 60 g per hour.^[3] Combining carbohydrate types that use separate intestinal transport routes — glucose alongside fructose — raises that ceiling. A critical review of glucose–fructose composite formulations reported enhanced carbohydrate oxidation and improved gut comfort relative to single-saccharide formulations.^[4] That review drew mostly on cycling studies in men, so the population is narrower than the advice it gets used to justify.

In other words: at higher intakes, research suggests mixing carbohydrate types may be part of the solution rather than the problem.

The variables the myth ignores

Blood flow is redistributed away from the digestive tract during hard exercise. Controlled work in healthy men demonstrated that exercise-induced splanchnic hypoperfusion produces measurable gut dysfunction.^[5] This is intensity-driven and happens regardless of what you swallowed.

Heat compounds it. Research in endurance athletes running under moderate environmental heat stress found elevated circulating markers of gastrointestinal integrity disruption compared with cooler conditions.^[6] For athletes training in Singapore — mean annual relative humidity around 82%, afternoon temperatures above 32°C during inter-monsoon periods^[7] — this is not a marginal consideration.

The part almost nobody mentions

Gut tolerance is adaptable. Research on training the gastrointestinal tract indicates that gastric emptying, stomach comfort, and carbohydrate absorption capacity can all improve with deliberate practice, with measurable symptom reductions reported over roughly two weeks.^[8] The athletes who tolerate higher carbohydrate intakes are frequently the ones who have practised doing so.

Where honey-based gels sit in this

Honey contains naturally occurring glucose and fructose in meaningful proportions rather than a single sugar type.^[9] That means a honey-based gel already delivers carbohydrate across more than one intestinal transport route without anything being added. But natural composition does not suspend absorption ceilings, and any product marketing implying otherwise should be treated with suspicion — including ours.

What to do instead

Work out your hourly carbohydrate target for your event duration using the Race-Day Fuelling Calculator, rehearse it at race-like intensity, and adjust based on what your gut actually tells you. For the fuel you take before the start — where none of these in-race variables apply — see The Pre-Load Protocol.