Three athletes line up for the same marathon. One is carrying gels, one chews, one a carbohydrate drink. All three believe their choice is optimal. By the finish, one of them will be right — and it's not necessarily the one with the most expensive product.
The debate between energy chews, gels, and liquid carbohydrate is less about which format is physiologically superior and more about understanding how each interacts with your gut under race conditions — and matching the format to the athlete, event duration, and environmental context.
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Gastric Emptying: The Rate-Limiting Step
All three formats deliver carbohydrate. The variable that distinguishes them is gastric emptying rate — how quickly each format exits the stomach and reaches the small intestine for SGLT1 and GLUT5 transporter absorption.
Liquid carbohydrate solutions (isotonic or hypotonic drinks, 6–8% concentration) empty fastest. At concentrations of 6–8% carbohydrate, gastric emptying rate approximates that of water — approximately 20–30 minutes to peak plasma glucose elevation. Hypertonic solutions (above 8%) slow emptying and increase GI distress risk.
Gels — semi-viscous, typically 1300–1500 mOsm/kg — empty more slowly than isotonic drinks when consumed without water. The standard recommendation of 150–200mL water per gel dilutes the bolus to near-isotonic, recovering faster emptying. Without water co-ingestion, gel carbohydrate arrival at the absorptive surface is delayed and GI cramping risk rises.
Chews (solid or semi-solid confectionery formats) introduce an additional variable: mastication time and salivary amylase pre-digestion. Chewing initiates starch hydrolysis via salivary amylase, but the main functional consequence is slower gastric transit compared to gels or drinks — researchers (Pfeiffer et al., 2012, International Journal of Sports Physiology and Performance) found no significant difference in exogenous carbohydrate oxidation rates between liquid, gel, and semi-solid formats at matched carbohydrate intakes, suggesting the absorptive capacity is similar once the carbohydrate clears the stomach.
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Palatability and Sensory Fatigue: The Factor Nobody Talks About
Pure physiology tells only half the story. The other half is palatability fatigue — the progressive sensory aversion to any repeated taste stimulus over hours of racing.
In events under 3 hours, sweet gel formats are well-tolerated. Beyond 3–4 hours, most athletes report declining willingness to consume sweet, concentrated products. A 2020 analysis by Jeukendrup noted that GI symptoms in ultra-endurance events cluster around the 5–7 hour mark, with sweet aversion and palatability fatigue preceding actual gastrointestinal dysfunction in many cases.
Chews offer a partial solution: the textural variety and slower oral processing provide sensory novelty absent in gels. Athletes managing ultra events often report chews as more psychologically satisfying during the late race period, even when caloric delivery is equivalent.
Liquid carbohydrate formats (carbohydrate-electrolyte drinks) have the advantage of simultaneous hydration and fuelling — a meaningful logistical simplification for athletes who struggle to drink and consume solids simultaneously under race stress. The limitation is carrying volume: a 500mL bottle supplies only 35–50g carbohydrate at 7% concentration, requiring frequent resupply.
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GI Mechanical Stress: Running vs Cycling Format Selection
The biomechanics of the activity significantly influence format selection. Running generates vertical impact forces that compress the gastrointestinal tract, reducing splanchnic blood flow by 60–80% and increasing mechanical disruption of digestion. This makes liquid and gel formats preferable to chews during high-intensity running, as chews require gastric solid processing under conditions of reduced mesenteric perfusion.
In cycling, reduced GI mechanical stress and the option to carry food on the bike (jersey pockets, top tube bags) make chews, bars, and solid foods more practical. Many experienced cyclists reserve gels and liquid carbohydrate for the final 30–60 minutes and any high-intensity surges, relying on real food and chews for the bulk of fuelling.
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Practical Selection Framework
For events under 2.5 hours: gels with water are the most efficient format — high carbohydrate density, known absorption kinetics, easy to carry.
For events 2.5–5 hours: a hybrid strategy — gels and chews alternated — reduces palatability fatigue and provides textural variety without sacrificing carbohydrate delivery.
For events over 5 hours: real food, chews, and liquid carbohydrate should form the backbone, with gels reserved for intensity surges or periods when solid food is impractical.
In all cases, race-day format should be trained in practice. GI adaptation to a specific delivery format occurs with repeated exposure, and debut use of a new carbohydrate format on race day is a reliable source of mid-race gastrointestinal surprises.
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For athletes calculating exactly how many servings of their chosen carbohydrate format to carry based on race duration, intensity, and target carbohydrate rate, the free calculator at winsport.uk/tools/nutrition/energy-gel-calculator estimates total carbohydrate needs and translates them into equivalent gel, chew, or drink servings.
Which carbohydrate format do you prefer for your long efforts, and has your choice changed as event duration has increased?