Most runners pick a gel based on what’s available at the expo or what a training partner uses. That’s not a strategy — it’s luck. The gel you choose, and when you take it, has a direct effect on your performance and your stomach. This guide breaks it down by use case so you can make an informed decision.
What makes a good energy gel?
Your body can absorb more carbohydrates per hour when you combine glucose and fructose rather than relying on a single source. Both sugars use separate absorption pathways in the intestine, which means the ceiling for carbohydrate uptake is higher and the risk of gastrointestinal (GI) distress is lower. Every gel worth considering is built around this principle.
Beyond the formula, four things determine whether a gel works for you: carbohydrate content per sachet, stomach tolerance at race intensity, consistency of the texture, and ease of opening while moving. A gel that is technically sound but impossible to swallow at kilometre 18 is not a useful gel.
Best for race day: Maurten Gel 100
If stomach tolerance at high intensity is your priority, Maurten is the benchmark. Each sachet of Maurten Gel 100 delivers 25 grams of carbohydrates using a patented hydrogel technology built from just six ingredients — no colours, no flavours, no preservatives. The hydrogel structure encapsulates the carbohydrates and carries them through the stomach to the intestine, which significantly reduces GI distress at race pace.
The texture is firm rather than syrupy — closer to loose jelly than a traditional gel. The taste is neutral, which becomes a major advantage over longer distances when sweet flavours start to feel overwhelming. The downside is cost: Maurten is the most expensive option in this category. For race day, it is worth it. For every training session, the cost adds up fast.
Use it for: half marathons, marathons, and any race where you are running at sustained high intensity and stomach tolerance is a priority.
Best for long training runs: SiS Beta Fuel
Where Maurten wins on stomach tolerance at race pace, SiS Beta Fuel wins on volume. Each sachet delivers 40 grams of carbohydrates in a 1:0.8 ratio of maltodextrin to fructose — designed specifically for efforts longer than two hours. That is 60% more carbohydrates per sachet compared to Maurten Gel 100, which matters when you are targeting 80 to 90 grams of carbohydrate per hour on a three-hour long run.
The consistency is thicker than Maurten but manageable. Flavours include orange, strawberry and lime, and a neutral option — the neutral version is worth trying if you are prone to flavour fatigue on longer efforts. One practical note: the packaging can be difficult to tear open cleanly mid-run. Pre-tear it slightly before you head out.
Use it for: long training runs over 90 minutes, back-to-back training days, and any session where hitting a high carbohydrate intake per hour is the goal.
Best all-round option: GU Energy Gel
GU Energy Gel has been the default gel for recreational runners for decades, and there is a reason for that. Each 100-calorie packet combines maltodextrin and fructose to maximise absorption while minimising GI distress, with sodium to support hydration and branched-chain amino acids to reduce muscle fatigue. At roughly half the price of Maurten, it is the most accessible option for runners who gel regularly in training.
The flavour range is wide — over a dozen options, with caffeinated and non-caffeinated versions. That variety is genuinely useful across a full training block when taste fatigue becomes a real problem. The formula is not as clean as Maurten, and the texture is more traditional — slightly sticky and sweet. Not a problem for most runners, but worth testing in training well before any target race.
Use it for: regular training runs, athletes new to gels who want to experiment without a high cost per unit, and as a backup gel alongside Maurten on race day.
How to use gels: timing and common mistakes
The most common mistake is taking gels too late. By the time you feel your energy dropping, you are already behind. The standard protocol: start fuelling at 45 minutes into any run over 75 minutes, then take a gel every 30 to 45 minutes after that. Do not wait until you feel empty.
Always take gels with water, not a sports drink. Most gels are designed to be absorbed with water alongside them, and combining them with a carbohydrate drink can push your hourly intake into territory that causes stomach issues. Maurten is the exception — the hydrogel technology makes water less critical — but staying hydrated remains important regardless.
Test every gel in training. Race day is not the moment to discover that a specific gel does not agree with your stomach. Build your fuelling protocol into your long runs at least four to six weeks before your target race, at the same intensity you plan to race at.
Which gel is right for you?
If you are training for a half marathon or marathon and want a clear split: use Maurten Gel 100 on race day for stomach safety, and SiS Beta Fuel on long training runs for volume and cost efficiency. If budget is a constraint across both training and racing, GU covers both roles at a lower cost per gel.
The right gel is ultimately the one you have tested, tolerated, and timed correctly. The science only works if the execution does.
For more on race day fuelling strategy from start to finish, read our guide on how to fuel a half marathon. For the full picture on running nutrition, the running nutrition guide covers everything from daily eating to race week.
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