Everything You Need To Know About Energy Gels

When you’re running, especially over long distances, your body relies on two main fuel sources to power your muscles: fat and carbohydrates. While fat is abundant, it’s slow to convert into usable energy—making it less effective when you need a quick boost, like during a marathon or a tough training session. That’s where carbohydrates come in. Carbohydrates are your body’s preferred and primary fuel source during faster, more intense efforts. The faster you run, the more your muscles depend on carbohydrates for energy.

However, your body can only store a limited supply of carbohydrates in the form of glycogen within your muscles. These glycogen stores start to run low after about 90 minutes of running at half-marathon pace and around 120 minutes at marathon pace. This means that, for most runners, glycogen depletion hits around the halfway mark of a marathon—often when you start to feel your energy dip and your legs grow heavy.

That’s where energy gels come into play. These small, portable sachets are packed with fast-acting carbohydrates, designed specifically for runners, cyclists, and endurance athletes. They deliver a concentrated burst of energy right when you need it most, helping to top up your dwindling glycogen stores and keep you feeling strong through the toughest parts of your run.

Most energy gels blend simple and complex carbohydrates for quick absorption, and many include added electrolytes, caffeine, or amino acids to further support your performance and hydration. Think of them as your pocket-sized energy boost—easy to carry, quick to consume, and formulated to help you push through those challenging miles and finish strong.

After consuming an energy gel, the blood absorbs the simple sugars, giving you a spike in energy. Through the blood, these sugars are then absorbed by your active muscles and organs, providing your body with a short energy boost.

Energy gels contain about 25g of carbohydrates per gel, with one gel providing about 45 minutes of running. However, taking two at a time does not provide 90 minutes of running. Instead, you’re likely to crash as your body attempts to process the sugar.

Some energy gels may contain other ingredients to boost your performance, such as electrolytes to replace lost minerals or caffeine to open up the blood vessels and speed up energy delivery. Some gels are fruit-flavoured, containing antioxidant-rich fruits like berries, which can help clear the muscles of waste products.

There are several types of energy gels, each designed to suit different preferences and needs:

The perfect time to take an energy gel depends on the individual. Every runner absorbs and processes carbohydrates at a different rate. Some can feel the effect within three minutes, while for others, it might take up to 15.

As your body diverts blood from your stomach towards your active muscles, your absorption rate slows. Sometimes, your stomach shuts down completely, and this is, unfortunately, the most common cause of unwanted toilet stops during a run!

The most important rule is to take the gel before you need it, not as you feel yourself crashing or hitting the wall. We recommend you practise with energy gels throughout your training to ensure you know when and which energy gel to take. 

The timing of energy gel consumption can make a significant difference in your performance:

• For Activities Under 1 Hour → Generally, you don’t need energy gels; your body’s glycogen stores are sufficient.
• For Activities Over 1 Hour → Take your first gel 60–90 minutes into your activity, then every 30–45 minutes thereafter to maintain energy levels.
• Before Exercise → Some athletes take a gel 10–15 minutes before starting, especially if they haven’t eaten recently.
• With Water → Most gels (except isotonic) should be consumed with water to aid absorption and prevent stomach upset.

While energy gels are ideal for marathon runners, they’re not to everyone’s taste. Although usually water-based, they vary in consistency and intensity in taste.

With so many on the market, flavours vary from vanilla, chocolate, and coffee to lighter, fruity flavours like orange, apple, and berries. We recommend testing a few different brands and styles on practice runs to find the consistency and flavour right for you.

The number of gels you need depends on the duration and intensity of your activity:

• Half Marathon (1.5–2.5 hours) → 2–4 gels, spaced 30–45 minutes apart.
• Marathon (3–5 hours) → 4–8 gels, depending on your fuelling needs and tolerance.
• Ultra Events → May require additional gels or other carbohydrate sources.

Always practice your fuelling strategy during training to avoid surprises on race day.

Choosing the right energy gel is a personal journey, as everyone’s body and taste preferences are unique. Start by considering the carbohydrate content of each gel. Most runners benefit from gels that deliver around 20 to 25 grams of carbohydrates per serving, which is generally enough to provide a noticeable boost without overwhelming your digestive system. If you tend to sweat heavily or train in hot conditions, it’s wise to look for gels that include added electrolytes such as sodium and potassium. These can help replace the minerals lost through sweat and support better hydration, reducing your risk of cramps during long efforts.

Another important factor is caffeine. Some energy gels contain caffeine for an extra kick of alertness and focus, which can be particularly helpful during the later stages of a long race or when you need a mental lift. However, caffeine can affect people differently, so it’s best to test these gels during training to gauge your tolerance before relying on them in a race.

Dietary preferences and sensitivities also play a big role in your choice. Fortunately, many brands now offer vegan, gluten-free, and organic options, so you can find a gel that aligns with your nutritional needs and values. Flavour and texture are equally important—after all, you’ll want something you actually enjoy eating, especially when you’re tired. It’s a good idea to try a few different brands and flavours during your training runs to discover what sits well with your stomach and tastes good even when you’re pushing hard.

Ultimately, the best energy gel for you is the one that fits seamlessly into your fuelling strategy, tastes great, and keeps you feeling strong throughout your run. Experiment during training, listen to your body, and you’ll soon find the perfect match to power your performance.

• Don’t Overdo It → Too many gels can cause stomach issues. Stick to recommended intervals and listen to your body.
• Practice, Practice, Practice → Use your training sessions to perfect your fuelling and hydration strategy.
• Mix and Match → Some runners combine isotonic and higher-carb gels, or alternate between caffeinated and non-caffeinated options for balance.
• Stay Hydrated → Dehydration can worsen stomach issues and reduce gel effectiveness. Sip water regularly.
• Check Expiry Dates → Gels can go off—always check before race day.