Energy gels in endurance sports: Everything you need to know

Anyone who exercises at a high intensity for more than an hour will eventually reach their limit: the body’s energy reserves run low, the legs feel heavy and concentration wanes. Energy gels are designed to prevent this. They are compact, quick to take and provide a lot of energy in a short space of time.

​A brief history of the energy gel

In 1987, sports scientist Timothy Noakes developed the first energy gel in South Africa: 25 grams of concentrated carbohydrates in a small plastic sachet. The South African company Leppin Sport took over production under the name Squeezy – derived from the English verb ‘to squeeze’. The product initially remained unknown in Europe until Roger Milenk discovered it at the Ironman in Roth in 1993, acquired the formula and distribution rights, and launched Squeezy on the German market in 1994. What was once a niche solution for triathletes is now a market worth billions – and the gels have grown significantly since then: many gels now provide 40 to 45 grams of carbohydrates.

What is an energy gel?

Put simply, an energy gel is concentrated sugar in gel form – packaged in a small portion that you can swallow without chewing during training and competition. Most gels contain between 20 and 45 grams of carbohydrates per portion. Carbohydrates are the fuel that muscles can utilise most quickly. Some gels also contain electrolytes, caffeine or vitamins.

Sources of carbohydrates – what’s in them?

Not all sugars are the same. Energy gels contain various sources of carbohydrates – each with different properties:

The glucose-fructose ratio

This is where things get a bit more biochemical, but it’s worth understanding.

The small intestine absorbs glucose and fructose via various ‘entry points’. When simple glucose is absorbed, this can quickly result in an uptake of 60 grams per hour. This figure varies from person to person and can be increased through regular training combined with a high carbohydrate intake. Those who combine glucose and fructose can, in theory, absorb more carbohydrates per hour.

The two standard mixing ratios:

2:1 (two parts glucose, one part fructose): The tried-and-tested formula. Provides up to 90 grams of carbohydrates per hour and is the better choice for most athletes when consuming amounts up to this level; well tolerated and scientifically proven.

1:0.8 (one part glucose, 0.8 parts fructose): The newer formula with more fructose. It makes sense particularly when you’re approaching 100 to 120 grams per hour – but only if your gut is sufficiently trained.

Important: The optimal mix ratio varies depending on the total amount. If you consume less than 90 g per hour, a 2:1 ratio is often better, because the glucose transporter is not yet working at full capacity at these levels and a higher fructose content increases the risk of digestive problems.

Anyone buying a gel that contains only maltodextrin or glucose and no fructose is limited to a maximum of 60 grams per hour. This isn’t a problem for shorter rides; for long races, however, it may not be enough.

​Fructose malabsorption – what those affected should know

Some people have difficulty digesting fructose. The fructose then passes undigested into the large intestine, where bacteria ferment it. This results in bloating, cramps or diarrhoea. Estimates suggest that 10 to 50 per cent of the general population are affected; the proportion is thought to be even higher amongst endurance athletes.

Symptoms often only appear during physical exertion. Even people who have no trouble digesting fructose in their everyday lives may still experience problems whilst exercising, as the blood supply to the gut is reduced during high-intensity activity.

A helpful mechanism: glucose facilitates the absorption of fructose. A balanced glucose-to-fructose ratio (2:1 or 1:0.8) is therefore better tolerated by many people with this condition than fructose on its own, such as that found in agave syrup.

A handy tip: If you suspect you may not tolerate fructose well, it is best to start with a pure glucose gel – in other words, one without fructose in the list of ingredients. If this goes down well, introduce fructose gradually: start with a gel containing a small amount of fructose, then increase the amount until you can feel where your limit lies. That is precisely why the manufacturer Squeezy offers gels with no fructose, low levels of fructose and high levels of fructose.

Note: Fructose malabsorption is not the same as hereditary fructose intolerance, a rare, congenital condition in which a liver enzyme is missing and even small amounts of fructose can lead to severe hypoglycaemia and liver damage. Those affected have usually known this since childhood.

​Lactate gels – a special feature

A new niche has emerged during the 2026 Tour de France A new trend has emerged on the gel market: lactate gels. These specialised energy gels contain sodium lactate – the sodium salt of lactic acid – as an additional source of energy. Lactate can be used directly as fuel by the heart muscle and certain muscle fibres. At the same time, the sodium bound in the sodium lactate provides a significant amount of electrolytes – much like in traditional salt supplements. These gels are rare and considerably more expensive than traditional carbohydrate gels.

How many carbohydrates per hour?

The following guidelines are taken from two scientific reference works: the recommendations of the American College of Sports Medicine (ACSM, 2016) and the UCI Sports Nutrition Project, a position paper published in 2026 specifically for cycling, drawn up by Jeukendrup et al. in the International Journal of Sport Nutrition and Exercise Metabolism.

• Up to 60 minutes: No intake is necessary; the body has sufficient reserves.
• 60 minutes to 2.5 hours: 30 to 60 grams per hour is sufficient.
• Over 2.5 hours: Up to 90 grams per hour as a general guideline, ideally in the form of a glucose-fructose combination; recent studies show that trained athletes with a gut that has been properly prepared can absorb up to 120 grams per hour.

Important: The 120-gram mark is not a target for amateur athletes. It requires systematic bowel training over several weeks and high levels of exertion, and in practice is primarily relevant for ambitious competitive athletes and professionals. For recreational cyclists, 60 to 80 grams per hour is a realistic and easily tolerated target for most long rides. Anyone wishing to consume more should increase the amount in small increments, for example by 10 grams per week.

These figures are upper limits. What each individual’s body can tolerate varies greatly from person to person.

​Timing – when should I take the gel?

One of the most common mistakes is waiting to take the gel until your legs are already feeling heavy. By that point, the energy dip is already underway, and it takes a while for the gel to take effect. The first carbohydrates reach the muscles after just three to five minutes, but it can take up to 25 minutes for all the carbohydrates in a serving to be fully absorbed. If you wait until you realise you need energy, you’ve waited too long.

A more effective approach is to adopt a proactive strategy: take a gel every 30 to 45 minutes, regardless of how you’re feeling at the time. On long rides or in races, start doing this from the very first hour.

​​A common mistake in competition

A classic beginner’s mistake is to try out the gel or gel strategy for the first time during a race. What works in your head needs to be familiarised with by your body first. Always test new products in training first – at a similar intensity to that of a race. Anything that upsets your stomach in training will do so even more under the stress of competition.

Getting your gut used to the amount of carbohydrates

Anyone who suddenly tries to consume 90 grams of carbohydrates per hour without having trained for it first risks stomach cramps, nausea or diarrhoea. The reason is that during strenuous exercise, blood flows mainly to the muscles, whilst the gut receives less of it and works more slowly.

The good news is that your gut gets used to it over time. If you train regularly with gels and gradually increase the amount, you’ll noticeably improve your tolerance. Six to ten weeks are enough to see the first results. Important: make sure you train at higher intensities too, not just on leisurely rides.

​What the professionals do in the peloton is in a league of its own: during intense one-day races, they consume up to 120 grams per hour, and some riders are said to train their digestive systems to handle even greater quantities. Just how much of this is actually absorbed and utilised has not yet been conclusively proven by science.

​Should you take the gel with water – yes or no?

Yes, in most cases. A gel without enough liquid can sit in the stomach and cause nausea or cramps, because the body first has to draw on water to dilute the concentrated gel.

As a rule of thumb, allow around 150 ml of water for every 20 grams of carbohydrates. So a small gel containing 20 grams requires a large mouthful, whilst a large gel containing 40 to 45 grams requires around 300 to 350 ml – almost half a bottle.

One exception is so-called isotonic gels. These are already diluted to such an extent that they are easily tolerated without any additional liquid. Per serving, they contain a similar amount of carbohydrates to a normal gel, but are significantly more liquid and come in a larger sachet.

Consistency – watery, syrupy or jelly-like?

Gels differ not only in their contents but also in their texture. Which one feels better is a matter of personal preference.

Aqueous: Almost like a drink. Easy to swallow, even without water afterwards. Typical of isotonic gels.

Syrupy: The most common type. Thick like honey; you need to apply a bit of pressure to squeeze it out. Many classic gels fall into this category.

In between: Some gels are deliberately less sticky and more fluid than traditional syrups, without being watery. One example is Precision Fuel PF 30: less sticky in the mouth, easy to swallow, but not a hydrogel.

Gel-like (hydrogel): The best-known example is Maurten. In a hydrogel, the carbohydrates are embedded in a biopolymer matrix that passes quickly through the stomach. The texture is similar to jelly, and the taste is neutral.

Gel flasks – who are they suitable for?

Instead of using lots of individual sachets, you can pour gels into a soft bottle – known as a ‘gel flask’ – and use it whilst cycling. If you make the switch consistently, it reduces packaging waste and is more practical on long rides. Thin-consistency or gel-like products work well. Thick gels are more difficult to pour in and squeeze out. Several manufacturers now offer bulk packs for filling gel flasks. Others provide powder for you to mix yourself. It’s important to clean the flask thoroughly after use – sugar residues provide a good breeding ground for germs.

Electrolytes – a bonus or a must?

When we sweat, the body loses not only water but also minerals. The most important of these is sodium. Potassium, magnesium and calcium are also lost, but in significantly smaller amounts, and are usually replenished through meals as part of a balanced diet.

Whether electrolytes are contained in the gel varies from manufacturer to manufacturer. Some brands, such as Precision Fuel, follow their own hydration strategy: the electrolytes are not supplied via the gel, but via a separate electrolyte drink. Other manufacturers include at least some sodium directly in the gel.

This is not a shortcoming on either side. The overall strategy is what matters: anyone who drinks only water and consumes gels without electrolytes may end up with a deficit during long, strenuous training sessions.

Additives

Most gels contain preservatives. The most common is potassium sorbate (E 202), which is considered safe. Sodium benzoate (E 211) is a more controversial ingredient: when combined with ascorbic acid (vitamin C), which is used as an antioxidant in some gels, benzene – a carcinogenic compound – can form under certain conditions. The quantities produced are very small, but anyone who pays attention to a clean list of ingredients should check whether both substances appear together. None of the gels we tested contain this combination.

Caffeine

Caffeine has been shown to improve endurance performance and is one of the most thoroughly researched sports supplements. In this article, we explain in detail exactly how caffeine works in cycling. Caffeine gels are typically used in the second half of a long race, when the intensity increases and concentration begins to wane. The usual dose is between 30 and 75 mg per gel.

There is no clear scientific evidence to suggest that one should avoid caffeine during training in order to maximise its effect during competition. Recent studies show that regular caffeine consumers achieve similar performance benefits to those who otherwise avoid caffeine. If you want to be on the safe side, you should still use caffeine gels selectively and avoid taking them daily during training.

Important: Not everyone can tolerate caffeine. Those who are sensitive to it may experience nervousness, a racing heart or stomach problems. Caffeine has a half-life of five to six hours, which means that if you take a gel in the afternoon, it may still affect your sleep in the evening.

Dental health

Energy gels are sweet and often sour; citric acid is frequently listed among the ingredients. Citric acid has a more erosive effect on tooth enamel than other acids, such as malic acid. To make matters worse, people often breathe through their mouths whilst exercising, which reduces saliva flow. Saliva is the natural protector of tooth enamel. It is therefore no coincidence that dental problems are widespread amongst professional cyclists. Find out more in our interview with sports dentist Dr Siegfried Marquardt.

Three simple steps can help: rinse your mouth with water after using the gel, swallow the gel quickly rather than sucking on it slowly, and wait at least 30 to 60 minutes before brushing your teeth, as the enamel is softened after eating acidic foods and the toothbrush would otherwise scrub it away.

​Gels and solid food – what should you bear in mind on long rides?

Anyone riding for four hours or more should not rely on gels as their sole source of energy. Solid or semi-solid food provides variety for the stomach and reduces the strain caused by highly concentrated sugary products. Many professional cyclists combine gels during intense phases with solid food during less strenuous sections.

Important to bear in mind when choosing: During long rides, solid food should be as low in fat and fibre as possible. Bananas and rice cakes are ideal because they are easily digested. Sandwiches, on the other hand, are harder to digest during high-intensity exercise.

Rule of thumb: the longer the period of exertion, the more important it is to supplement your diet with proper food.

What’s your favourite gel? Leave us a comment.