Best Energy Gels UK 2026: Tested Picks for Running and Cycling

Energy gels are the least glamorous piece of kit in endurance sport and the one most likely to ruin a race. Get the timing and the carbohydrate load right and you will run the last 10k of a marathon feeling like the same athlete who started it. Get it wrong and you spend twenty minutes hunting for a portaloo while your split times fall apart.

The good news is that the science here is settled enough to buy on. For efforts of one to three hours, research puts the useful range at 30g to 60g of carbohydrate per hour, rising towards 60g to 90g an hour for anything longer than three hours when the gel uses more than one type of sugar. That last detail is the whole reason modern gels blend glucose with fructose: glucose transport saturates at roughly 60g an hour, and fructose sneaks in through a different door.

1. Science in Sport GO Isotonic Energy Gel: Best Overall

SiS built its reputation on one idea, which is that a gel already mixed to isotonic concentration does not need washing down with water. It works. The 60ml sachet delivers 22g of carbohydrate and goes down like a thin syrup rather than the tar most gels resemble, so you can take one between drinks stations without doing the sticky-mouth shuffle for the next mile.

The trade-off is bulk. A 60ml sachet is noticeably bigger and heavier than a 40g concentrated gel, so carrying six of them for a marathon means finding somewhere to put them. Carb density is also on the low side at 22g, so runners aiming at the upper end of the fuelling range will need more sachets than they would with a 30g gel. For most club runners and first time marathoners, the reliability is worth more than the gram counting.

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2. Maurten Gel 100: Best for Race Day

Maurten is the gel you see littering the road at elite marathons, and the price reflects that reputation. Each 40g sachet carries 25g of carbohydrate in a hydrogel that sets into a jelly-like texture, the idea being that encapsulating the sugars lets the gel pass through the stomach with minimal irritation before releasing them further down. Runners who cannot tolerate anything else often get on with these.

It is expensive at roughly £34 for twelve, and the texture divides people completely. Some describe it as flavourless and easy, others cannot get past chewing something with the consistency of a jellyfish while running at threshold. There is also no caffeine in the standard Gel 100, so a separate product is needed if you want that. Try one on a long run well before you commit to a race day plan built around them.

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3. Precision Fuel PF30: Best High Carb Gel

Precision Fuel came out of the Precision Hydration lab in Hampshire, and the PF30 is built for the modern high carb approach: 30g of carbohydrate in one small sachet, deliberately mild and neutral in flavour so that taking four or five over a long ride does not make you gag on sweetness. Two of these an hour puts you at 60g without much effort or bulk.

Neutral flavour is exactly what some people want and exactly what others find grim, so opinions split sharply. It is also a premium price at close to £35 for fifteen, and 30g in a small volume means you should be drinking properly alongside it. For ultra distance, long sportives and anyone who has trained their gut to handle high intakes, this is the most efficient way to carry fuel here.

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4. HIGH5 Energy Gel, 20 pack: Best Value in Bulk

HIGH5 has been fuelling British sportives and marathons since the 1990s, and the 20 pack is how you fuel a whole training block without wincing at the receipt. Each 40g sachet gives 23g of carbohydrate from natural fruit juice, with no caffeine in the standard version and a genuinely pleasant berry flavour that does not taste synthetic.

At around £16 for twenty, the price per gel is roughly a third of what Maurten asks. The gel is concentrated rather than isotonic, so you do need water with it, and the sachets can be fiddly to tear open with cold or sweaty hands. Neither of those is a reason to pay four times more for training fuel.

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5. HIGH5 Energy Gel, 8 pack assorted: Best Starter Pack

Before you buy twenty of anything, find out whether your stomach agrees with it. The assorted 8 pack costs under a tenner and gives you several flavours to test across a few long runs, which is the sensible way to work out what you can tolerate at race pace rather than sitting on the sofa.

Per gel it is worse value than the 20 pack, and the mixed flavours mean you will end up with one you actively dislike. That is the point of a trial pack. Use it as a screening exercise, then buy the flavour that worked in bulk.

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How much carbohydrate you actually need

Those upper numbers only work if you have practised them. Pushing 90g an hour into an untrained gut is a reliable way to end a race early, and the sensible progression is to add roughly 10g an hour every few weeks during long training sessions until your stomach stops complaining.

Stomach trouble, and how to avoid it

Gastrointestinal symptoms are the single most common reason runners abandon a fuelling plan, and the causes are boringly predictable. A review of exercise related gut complaints found that multiple transportable carbohydrates such as glucose and fructose tend to produce fewer symptoms than single carbohydrate solutions at the same intake, largely because absorption is spread across two transport routes rather than backing up in the intestine.

Practical rules that work:

• Take water with any concentrated gel, roughly 100ml to 200ml. Isotonic gels are the exception.
• Never trial a new gel on race day, not even a new flavour of one you already use.
• Spread the intake. Two half gels twenty minutes apart sits better than one large hit.
• Watch the total. Sports drink plus gels plus chews adds up faster than people expect, and doubling up on fuel sources is a classic marathon mistake.

If you are also losing a lot of salt on hot days, gels alone will not cover it. Pair them with proper hydration from our best electrolytes UK guide, and see our SiS GO Electrolyte review for the drink version of the same idea.

Caffeine gels, briefly

Caffeinated versions usually add 75mg to 100mg per sachet, which is roughly a strong coffee. The effect on perceived effort late in a long event is real, and the sensible pattern is to save them for the back half of a race rather than starting on them. Anyone sensitive to caffeine, or racing in the evening, should think carefully before adding more than one or two.

Which one to buy

If you are running your first half or full marathon, buy the SiS GO Isotonic gels and stop thinking about it. If you have a stomach that rebels at everything, spend the money on Maurten. If you are training six or seven hours a week and getting through gels like sweets, the HIGH5 20 pack is the only sane choice on cost. Track what you take and when using a running watch or a heart rate monitor, because a fuelling plan you can repeat is worth more than a perfect one you invent on the day.

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