Energy gels: what they are, how they work, and when and how to take them

All you need to know about energy gels including common ingredients, what to look for, how and when to take them

Energy gels: what they are, how they work, and when and how to take them

What is an energy gel?

Energy gels have been a common feature in the training regimes of triathletes since they first hit the market back in the mid 1980s. A cross between an energy bar and a sports drink, delivered in a tiny, easy-to-carry sachet, these concentrated ‘sugar hits’ deliver an easy, instant energy boost during long bouts of exercise, helping to replace depleted carbohydrate stores.


What ingredients are in energy gels?

Not only has their popularity grown, energy gels have also become more and more sophisticated. The first gels (Squeezy) were a simple sugar and salt mix, whereas nowadays the wide range of gels available gives the consumer the choice of added caffeine, extra B vitamins, a spectrum of electrolytes, antioxidants and even fats in the form of MCT’s (medium chain triglycerides). No wonder people are bewildered by the choice of gels.

Most energy gels on today’s sports nutrition market provide between 100-110 calories and 23-28g of carbohydrates, and energy gels with added caffeine provide 20mg-50mg of caffeine. Caffeine taken before exercise can lead to enhanced performance and may provide a mental burst of energy. But the effect on performance of caffeine taken during exercise (especially in such small dosages) is yet to be conclusively proven. It’s also worth bearing in mind that individual responses to caffeine vary widely. 

Other popular energy gel ingredients include:

  • Maltodextrin

A carbohydrate molecule made of short chains of glucose molecules. Maltodextrin is often preferred to free glucose because, gram for gram, it’s far less sweet (using pure glucose tends to make for an overly sweet product).

Maltodextrin’s also been mooted as less likely to cause bloating and cramps and, as a bonus, it’s an effective thickening agent, helping to produce the correct consistency.

  • Fructose

A simple sugar derived from fruit, which provides sweetness and (in combination with maltodextrin) a 2:1 carbohydrate blend.

Studies show that, compared to glucose- or maltodextrin-only drinks, significantly higher rates of energy absorption can be achieved when consuming a 2:1 blend of glucose and fructose – important during very long events when you need to maximise your energy intake.

Why sports drinks containing both glucose and fructose can help performance

  • Water

Although very concentrated, gels still need to contain some water. The amount of water affects both the taste and consistency. Low-water gels are thicker in consistency and tend to be sweeter.

High-water gels tend to be less sweet and more ‘liquid’, leading to a more refreshing taste. The drawback is that they’re heavier and bulkier per gram of carbohydrate delivered.

  • Sodium

A key electrolyte mineral (along with magnesium, calcium, potassium and chloride), sodium is important because it not only aids the uptake of glucose from the intestine, it helps to transfer water from the bloodstream into your working muscles.

Sodium bicarbonate: why athletes take it and how it improves performance

Dehydration and sodium: why replacing salt is crucial

This serves to underline the importance of consuming extra fluid along with gels, especially during longer events and in warm conditions.

  • Citric acid

As well as providing a ‘tangy’ taste (useful for fruit-flavoured gels), citric acid is extremely useful for ensuring that the gel product is sufficiently acidic to inhibit any bacterial growth.

This is important because the liquid nature of gels means they’re much more susceptible to spoilage on the shelf compared to energy bars or powdered drinks.

  • Flavouring

Makes the gel appetising. Natural flavourings from fruit extracts are among those most commonly used, although more exotic flavours are available

Which energy gels should you buy?

Energy gels cost around £1 per ‘hit’. Using gels on a daily basis could therefore prove to be quite an expensive habit. With that in mind, use them wisely and in moderation, and/or buy in bulk. Leading brands are available in boxes of 20-30 gels, which reduces the cost by 10-15% in most cases. Alternatively, you could experiment with a few natural ingredients at home. Ironman triathlete Brendan Brazier has some recipes in his book The Thrive Diet, and recommends blending dates, agave syrup, a touch of sea salt, and lemon or lime juice. The resulting ‘gels’ can be transported in small freezer bags or zip-lock bags. 

Honey is one of the most useful home ingredients, and is by far the most natural and unprocessed of all sugars. It contains a spectrum of vitamins, minerals and amino acids, which is perfect fuel during exercise when you need a quick and complete energy boost. You can also dilute honey if you find it too sweet or viscous. 

Gel taste and palatability is a vital consideration when buying and using any gels, so find one that you actually like and can digest easily. Another consideration is to find a gel that opens easily – you don’t want to be fumbling around during a race. Choosing one with an easy tear-lid is the best bet for a swift hit. 

Best energy gels reviewed, tested and rated

How do you take energy gels and how much water do they need?

Most gels on the market must be taken with around 200-300ml of plain water (not carbohydrate drinks), unless you choose an isotonic gel, which can be taken on its own. Science In Sport, a leading brand in sports nutrition, introduced the world’s first isotonic gel, the Go-Gel, which is now hugely popular with athletes of all standards. Isotonic simply means ‘of equal concentration’ and, in this case, describes the gel concentration as being in balance with the body’s fluids – so you don’t need to dilute it with water. 

Over-consumption of concentrated energy gels can cause dehydration, as water is drawn from the body and into the gut to facilitate absorption. It’s therefore of utmost importance to avoid over-consuming gels or taking them alongside energy drinks. 

Gels are by their very nature concentrated sources of sugars, so remember to take care of your teeth! Wash down the gels with water, and again, avoid over-consumption or snacking on energy gels. Sugar consumption is one of the leading causes of gum disease and even the great sport of triathlon isn’t worth that.

If you rely on gels only, you must remember to take on board extra fluid, particularly during longer training sessions/races and in warmer conditions.

In race conditions, this is usually not a problem; nearly all races have regular water stations so you can save weight and bulk by consuming your carbohydrate as gels, and topping up with water as and when needed.

If you consume all your carbohydrate in gel form, top up with plain water rather than carbohydrate drink (which would supply surplus carbohydrate). Consume too much carbohydrate and it won’t be absorbed – indeed, it could upset your stomach.

Should I use caffeine gels?

Like caffeinated carbohydrate drinks, energy gels containing caffeine are best used sparingly and towards the later stages of a longer event, when the fatigue-fighting properties of caffeine are most needed.

Most studies suggest that a caffeine dose of 3mg per kilo of body weight (around 200mg for a 70kg triathlete) is effective for fighting fatigue and prolonging endurance. Make sure you don’t exceed this amount.

How many energy gels should I take?

Check the ingredients and carbohydrate content of your gels. For standard gels – i.e. containing maltodextrin only and not a 2:1 glucose/fructose formulation – the maximum total amount of carbohydrate the average athlete can absorb is around 60g per hour.

Work out how many sachets an hour provides this amount (for example, 3 x 20g, 4 x 15g) and aim for this as a maximum amount, consuming them evenly across each hour.

Energy gel essentials

Try out a few for taste, palatability and how well you digest them. Basically, experiment and find one that suits you.

Make use of free samples if available.

The 25-30g gels are suitable to take every 30mins during exercise with 200-300ml of water (unless isotonic gels are used). Ensure the recommended intake of 60-80g carbs per hour is not exceeded (regardless of body weight).

 Avoid taking gels with carb drinks. This combination is likely to cause gut distress such as bloating, cramping or nausea.

Avoid over-fuelling with gels, and try them out in training before using them during races.

If you use gels on a near-daily basis, look for those that are free of artificial sweeteners such as Aspartame and Acesulfame K.