How many gels for a marathon?

The short answer: High5 suggests 2 to 3 energy gels an hour once you are running, which is about 8 to 12 gels for a four-hour marathon and 10 to 15 for five hours. Start with one gel every 30 minutes if you are new to gels, and move towards one every 20 minutes as your stomach gets used to them.

Why gels matter over 42 km

Your body stores only enough carbohydrate for roughly 90 minutes to two hours of hard running. After that, pace drops, which runners call "hitting the wall" (撞牆). A gel gives you carbohydrate that is quick to absorb, so you can keep topping up the tank instead of waiting until you are empty. Most people can take in about 60 to 90 g of carbohydrate an hour, so more is not always better: too much at once can upset your stomach.

For a 10K, you usually do not need gels at all. They start to matter once you are running for well over an hour, so think half marathons and up.

Work out your own number

• Pace: the faster you run, the more regularly you need to fuel. One gel every 20 minutes (or about every 5 km) suits experienced runners; one every 30 minutes is a gentle start.
• Body size: bigger runners generally need more. If you weigh over 90 kg, add a gel to the plan unless you are trying to lose weight.
• Weather: in a hot, humid race you sweat more and your stomach can be less happy, so practise in similar conditions (see our guide to electrolytes in Hong Kong heat).
• Practice: the only way to know is to try different amounts on your long runs. If you fade in the last 10 km, you probably need one more gel earlier on.

Always carry one or two spare gels. A dropped gel or a slower finish should not leave you short.

A simple gel plan for a marathon

1. Before the start: a carbohydrate-rich breakfast, plus one gel 10 to 15 minutes before you set off if you like. Our marathon fuelling plan covers the morning in detail.
2. From the start: 2 to 3 gels every hour, spread out, rather than waiting for the half-way point. A late gel gives a short lift; steady fuelling keeps your energy level.
3. The hard part (about 30 to 35 km): this is where many runners fade. Make sure you have not skipped earlier gels, and consider a caffeinated gel such as Energy Gel Caffeine, which has 30 mg of caffeine a sachet.
4. Sip water with each gel. A few mouthfuls helps your stomach process it, even if you do not feel thirsty.

If you use caffeine, alternate caffeinated and plain gels and keep to about 3 mg per kg of body weight in total. Do not use caffeine if you have a medical condition (including high blood pressure), are pregnant or breastfeeding, or are under 18.

Choosing a gel

• Energy Gel: the classic, in fruit flavours. Compact and light, so easy to carry a lot.
• Energy Gel Caffeine: the same, with caffeine for the later miles.
• Energy Gel Aqua: a lighter, more watery texture that many runners find easier to take on the move.
• Energy Gummies: chewable, if you prefer something less sticky.

Pick flavours you enjoy, because you will be eating them for hours.

Carrying and taking gels

• Tuck two or three into your shorts, or use a gel belt or race vest.
• Pin a gel to your race bib with a safety pin so it is always within reach.
• Slow to a walk to open the sachet, so you do not drop it or cover your hands.
• Take a small bite first to check your stomach copes, then the rest.
• Put empty sachets in the bins at the drink stations, not on the road.

Where to buy High5 gels in Hong Kong

You can find High5 at the shops and clubs listed on our Where to buy page, or order online from Streamline Sports, the official High5 distributor in Hong Kong. Try every product in training first, never for the first time on race day.