GU Energy Gel Review

If you’re an endurance athlete then you’ve probably already come across or been recommended taking energy gels to push you through rough slugs of your race.

Sometimes there is no amount of motivational words or songs to keep you going when your legs just want to give up and that’s why both professional and amateur athletes turn to energy gels to give them that boost of fire to keep those miles ticking by.

Energy gels work by using long-lasting energy from carbohydrates that are easily absorbed to be highly effective without disrupting the stomach’s system. They also contain amino acids which help to reduce muscle damage and help you feel more alert and aid with muscle recovery when you’ve finished training or racing. 

GU is one of the leading brands for energy gels and is hugely popular with athletes who need a helping hand to get through long-distance races like marathons.

We’ll be giving you our full review on Gu Energy Gels including an in-depth discussion about all the flavors they do, the different benefits, and our favorite selections.

GU Energy Gel Buying Guide

Size & Weight

If you’re inexperienced with energy gel’s then you’d probably take a glance at the one serving size packet of the GU ones and double-take it. The small packet is only 1.1oz and looks barely any larger than a small ketchup packet you’d get at a takeaway restaurant. However, when it comes to energy gels, size is pretty irrelevant and what matters is the ingredients that make up the gel. 

The mere size of these packets makes them more than ideal to carry in pockets or to store a few in your running vest without taking up too much space or weighing you down. They’re also great if you need to grab them off your friends or family from the crowd mid-race as you can keep them in your hand until you feel the need to consume one.

A banana weighs nearly 4 times the amount that one of the GU Energy Gels does, however, a GU Energy Gel can give you the same amount of energy that a banana would but in an miniscule packet that’s barely noticeable when being carried. 

Ease of Use

There are no set rules as to when you should try and take one of these GU Energy Gel, some athletes take them before they even begin their race, many will take them during their race for a good boost of energy whilst some will also take them after to aid with the recovery process. 

The packets are designed for convenience and easy useability so you won’t have to worry about slowing down or stopping during your race to consume them. All you have to do is rip open the top of the packet with your hands or even use your teeth if your hands are too sweaty and have no grip. 

Then squeeze all of the gel into your mouth, chug some water if you can to help the gel to absorb quicker, and wait for the benefits to kick in. You should consume the sachet of gel in one go and not save some for later in your race as you’ll need the full serving size to reap the full benefits of the energy-packed ingredients. 

Some people will take one gel 5 minutes before starting their race and then another 45 minutes into their race, but it’s recommended not to consume more than 2 of these Gu Energy gels in an hour. 


The ingredients in each different GU Energy Gel will vary depending on which flavor you’re consuming. 

Some of the most common ingredients you’ll find across the flavors are:

  • Maltodextrin
  • Water
  • Fructose
  • Leucine
  • Citric Acid
  • Calcium Carbonate
  • Sunflower Oil
  • Sodium Benzoate
  • Potassium Sorbate

Maltodextrin is highly processed despite being a carbohydrate made from starch. The maltodextrin works to slowly release energy to help you through your race and will allow your body to begin burning fat earlier on in your race so the transition between burning carbs and fat is not as painful for you. 

Leucine is one of the amino acids which will help reduce muscle damage helping you sustain your high endurance levels throughout the race without feeling like your body is fatigued or starting to ache. Leucine will also aid in your muscle recovery in the days and weeks following your race helping to reduce the stiff or achy legs and helping you back into training quicker. 

Citric acid is just one of the citrates that will help speed up the conversion of the carbohydrates from the sachet into energy molecules helping you to gain more energy in as little as 15 minutes from consuming your packet. 

Sodium Benzoate is a chemical food additive ingredient to help the gels last longer so you don’t have to keep them stored in a refrigerated setting. Whilst it is a very common and legal ingredient, there are some doubts about the use of sodium benzoate in energy gels, especially when combined with the ingredient vitamin C as this can morph into a cancer-causing agent. Potassium sorbate is also an additional ingredient used for preserving the gel to help it last longer. 

So as you can see from above, the majority of the ingredients used are not natural so if you’re someone who likes to fuel their body with organic or natural foods or ingredients then you may not feel convinced about these.

Nutritional Facts

Each serving size contains 100 calories with an average of 125 mg of sodium, 35 mg of potassium, and 23g of carbohydrates, although this will vary depending on the profile of each flavor and what the main benefits are. 

Considering the energy that these gels give you, the calorie intake is not as high as you’d expect but is enough to fill a gap in your stomach without risking any stomach aches or bloating that you’d experience from consuming food on the go.

Some of the flavors are available with or without caffeine, ideal for extremely testing conditions or aces. The caffeine will help boost concentration and also gives the perception of reduced effort during exercise so you don’t feel so fatigued. 

All flavors are vegan and gluten-free so will be able to suit most dietary requirements that athletes have. Some of the flavors are kosher, but you’ll need to check with the individual flavor that you have to confirm whether it is or not. 


The selection of flavors of the GU Energy Gel is admirable, being able to suit a variety of preferences of users.

Whether it’s a sweet caramel macchiato or chocolate outrage flavor you’re after or something more refreshing like lemon sublime or mandarin orange, then you’ll be able to find at least one that you love from the vast selection that GU has to offer. 

Below is the full list of flavors that GU has in their Energy Gel range:

  • Mandarin Orange
  • Lemon Sublime
  • Jet Blackberry
  • Chocolate Outrage
  • Espresso Love
  • Caramel Macchiato
  • Campfire S’mores
  • Birthday Cake
  • Hoppy Trails
  • Cola
  • Salted Watermelon
  • Cucumber Mint
  • Vanilla Bean
  • Tri-berry
  • Strawberry Banana]

You have got a good mixture of some classic flavors along with some more obscure yet tasty gels that’ll give you a few moments of delight during the energy-deficit moments of your race.

Our favorite flavor is the cucumber mint as it’s the most refreshing when washed down with some cool water, giving the illusion of drinking an ice-cold cocktail midway through a 3-hour race.

Energy Duration

Once you’ve consumed your energy gel sachet, you’ll have to wait around 15 minutes before you start to feel the benefits of the energy-filled ingredients.

The gel should sustain your energy levels and boost your performance for around 30 to 45 minutes and then you should feel a slight drag in your energy towards the 45-minute mark but you don’t experience a sugar crash like you would with an energy drink.

You’ll feel more focused around the 20-30 minute mark and feel less cloudiness in your head whilst finding it easier to stay motivated even in the later stages of the race.

Benefits of GU Energy Gels

The main benefits of the GU Energy gels are to boost your performance, helping you to power the sprint stages of your races more easily, or even just to sustain the pace to keep on track for your finish time target. 

You’ll also see a difference in your muscle recovery after you’ve finished the race, albeit you won’t feel like running a marathon the day after your race but you’ll find it easier to go about your everyday routine without experiencing extreme pain or stiffness.

You’ll also feel more focussed mentally, providing you with the alertness to keep your exercise form right so you don’t get injured or start to slip below your average pace.

Side Effects

Providing you consume the GU Energy Gels according to the directions you should experience no side effects. However, overconsumption of energy gels can lead to stomach cramps, vomiting, and diarrhea during or after exercise. 

Consuming more than the recommended serving size at once can also increase the chance of your experiencing an energy crash when the gel starts to wear off.

Final Words

The GU Energy Gels are one of the most advanced endurance and energy gels around at the moment and are well suited for a variety of dietary requirements.

They’re designed for maximum performance and optimum recovery time and will be suited for endurance hobbyists or full-time athletes.