Energy Gel Comparison

energy gelsWith energy gels being my primary energy source during ultras and weight being an essential consideration at the Marathon des Sables, I started thinking about which energy gels offer the greatest caloric density. While I initially planned on looking at only caloric density, I ended up comparing many other aspects of energy gels including their caffeine content, electrolyte content, and sugar profiles, as well as recording other ingredients of note. [Click on any table below to enlarge.]

For this review, I looked at 8 energy gel lineups that are commonly available at US retailers. [My highly scientific method for sample collection involved me sequentially looking at the gels on my shelf and then visiting a large outdoor retailer, a bike shop, and a large athletic goods store in an attempt to find additional gels.]

The gels included in this review are:

Caloric Density
As I mentioned above, my primary personal goal from this exercise was to identify the energy gels with the greatest caloric density, meaning the most calories per gram. Top honors are shared by Gu Roctane (see iRunFar’s review), Gu Energy Gel, and Honey Stinger at 3.0 calories (technically kilocalories) per gram. I would have guessed that watery PowerBar Gel (formerly known as Power Gel) would have had the lowest energy density, but at 2.6 calories/g it ranked much higher than Hammer Gel (2.4 calories/g) and basement dweller Accel Gel (2.2 calories/g).

energy gel caloric density comparison
Caffeine Content
We’ve previously discussed the possible endurance benefits of caffeine here at iRunFar. Regardless of where you fall on the subject of taking caffeine while running there’s an energy gel for you. Of the 8 energy gel lineups I investigated, only Gu Roctane was not available in a caffeine-free variety. On the other end of the spectrum, both CarbBoom! and Clif Shot offer a double espresso variety containing 100 mg of caffeine per pack. Between the extremes, caffeine contents for energy gels ranged from 20 to 50 mg.

energy gel caffeine content comparison
Electrolyte Content
In general, I rely on sports drink and electrolyte tablets to replace my salts when running. However, 7 of the energy gel varieties contain potassium and all 8 varieties of contain sodium. While all but a few of the gels contained low enough levels of sodium not to alter an electrolyte replacement strategy, it would be wise to keep in mind that a packet of Power Gel has 200 mg of sodium, Roctane has 125 mg, and Accel Gel has 100 mg.

energy gel electrolyte content comparison
Sugar Profile
I provide the following table in case you are curious as to which simple and complex carbohydrates your favorite gels contain. Simple sugars include fructose and dextrose (a form of glucose), as well as those found in honey and fruit juice. Maltodextrin is the prevalent complex carbohydrate found in energy gels. Clif Shot’s brown rice syrup contains a mix of simple and complex carbohydrates.

energy gel sugar profile comparison
Other Ingredients
Five of the energy gel lineups featured ingredients other than carbohydrates, electrolytes, and caffeine. These added extras included various vitamins, amino acids, and herbs. Take a look for yourself at what these gels contain.

energy gel other ingredient comparison
[Disclaimer: This comparison is only meant as an overview of energy gels. Food intake is of critical importance in longer endurance events and you should, therefore, carefully consider your nutritional plan. I recommend you further consult the product websites to which I provided links above. In addition, it is wise to personally test each variety and even each flavor of gel you intend to use in a key race before race day. You never know which ingredient may cause you stomach distress or which flavor will offend your palate.

Enough of the geeky stuff and disclaimers: What are your favorite energy gels and why?

[While I independently came up with the idea to compare energy gel caloric densities, I’ve got to tip my running hat to this UK comparison of energy gels that I first saw on However, I did not consult that comparison within months of designing my own. It’s interesting to see where and how they differ.]

There are 40 comments

  1. AnthonyP

    B – What a great post. I tend to use PowerBar Gel primarily, but have recently discovered Gu Roctane and have been working that into my routine. I'm a big consistency person when it comes to gels….too thick and I'll whine about it. I find PowerBar Gel to be nice and smooth.

  2. Meredith

    I used to eat gels out of necessity until Clif Blocks came on the market. If I ever ate more than 4 or 5 gel packs during a run/race i would get sick to my stomach or worse. They are probably the easiest to pack to MdS, but BLECH!

  3. Julien

    Well done on the test, I know how long it takes to gather and organise all the results. I can't find half the gels you mention in the UK, so your test complements mine pretty well.Keep running!

  4. Anonymous

    I've used e-Gel made by cranksports, which I don't think you can get in stores. It's a very thick gel that requires lots of water intake, and it also has 5 times the sodium as other gels. If you practice with it and get used to the right combination of gel/water, then I think it's a good bonk preventer (lots of maltodextrin, lots of calories, lots of sodium), but if you're not used to it, your stomach can go South in a hurry.CarbBoom is the easiest on the gut in my opinion, but leaves me feeling more bonky/lightheaded than the rest. The idea of adding protein, as in Accel, is good, but in Accel's case there seem to be weird additives that make it like a chemical spill in your digestive system.For long training runs where speed is not an issue, I've found that chia seeds mixed with water cannot be beat! The seeds are very small and hydrophyllic-meaning they retain water, so you stay hydrated. Again, if you don't practice you could be in big trouble if the mixture quantities are not ideal.TrailFool

  5. RunningMtns

    Great analysis!A few other things that might simplify comparison: Maltodextrin is simple starch and digests fairly quickly (30 min) to dextrose (aka glucose). Honey is roughly equal parts fructose and dextrose. Fruit juice is predominantly fructose. Brown rice syrup is about half complex starch (digests 90 min) and half maltose. BTW the name maltodextrin is somewhat unfortunate, since it contains negligible maltose.I have occasionally experienced stomach upset from high caffeine and sodium levels in PowerBar Gel, whereas I wasn't getting the same effect from other gels–YMMV. There is quite a lot of argument about the benefits of amino acids. Personally I find that 1/4 to 1/3 oz of beef jerky (roughly (8 to 10 g) every hour really helps–the source of protein is probably unimportant.

  6. RunningMtns

    Trail Fool makes a really important point about the need to practice with these products in training. There are also significant limits (total calories and carbohydrate concentration in the stomach) to know about. The special topics article "Biochemical Strategies for Ultrarunning" on my site talks at length about these limits and also how many calories (carbohydrate and fat) a runner needs and can realistically consume.

  7. Travis

    This is great information. Thanks for digging into all of this!!I used to use Hammer Gel, but they never agreed with me. I think its the fruit juice that they use in them. I also used Just Plain GU for a while until I discovered Clif.I currently roll all Clif and occasionally throw in the Honey Stiner line. Currently Clif Shot Blocks make up about 50% of my "gel like substances" consumed during training and races. I also use a variety of Clif Shots ranging from basic vanilla to the Espresso mentioned. It seems as the Clif line agrees with me the best, so even though there might be some added benfits to using some of the others mentioned, I'm not sure weather a change during active training would be worth the adjustment. Though if you do a test to see which ones are most resistant to freezing on cold runs, I might be up for checking those out :)

  8. cs

    I've been reading a few of these comparisons lately and it's surprising to me how many state that their stomachs don't agree with different gels. It's good to know, but for me the biggest issue is the packaging. Most of the gels have this large packaging, and I can't get it in my mouth. I like Gu because it works, and the packaging is small, so I can put it in a key pocket in my shorts, then when I go to eat it, I can squeeze the entire thing out with my teeth because the package is small enough to fit without scraping the sides of my mouth or gagging me (like the powerbar gels). It seems Hammer gel has tried to make something that works, but it's still way too big and you have to use your hands to squeeze it out.

  9. Will

    I'll second the recommendation for e-Gel. They are one of the higher calorie gels out there (150 calories), taste the best to me, and sit the best in my stomach.

  10. worm

    First off, thanks for the research. I'm with Meredith on this one. I love the consistency of shot blocks and how they're not so syrupy sweet. However, I do mix it up with Clif gel whenever I have need for it as they are faster to consume and with less energy/concentration required than blocks. I typically go for vanilla or espresso flavors.

  11. Anonymous

    I've been using the Gu Gels forever. The most important thing about using gels for me is that I use one just before a race, and then do one every 30-45 minutes, based on terrain and effort. I've found that I don't get the acid stomach lots of runners get if I drink water, not sports drink at that fuel/hydration cycle. I also tend to cut my sports drinks with more water, from one third to one half to avoid acid stomach. But I've also done training runs with mead, rather than sports drinks, in the camelbak… The Northern Virginia Minotaur.

  12. Iron Mountain Trail

    The best gel out there in my opinion is a new gel made by Advocare. A guy gave me a few packets and during my last training run (long run) I used them and was running extremely hard. These gels use malodextrin, fructose, and sucrose as the energy and having all three really worked in my system. They only have on flavor (fruit punch) but it tasted great (I hate gels too) and I took one every thirty minutes without any stomach issues. As for salt, Salt Stick tabs have worked well in conjunction too. Merry Christmas,Nick Whited

  13. Coach Spencer

    Never tried Stinger or Roctane, but of those listed, I'd choose:1. Carbboom 2. Accel 3. GU 4. Hammer5. Powergel6. ClifThe flavor of the Carbboom is the best by far in my opinion. Accel is relatively new to me & I like the protein. I like Gu for a change. I used to only eat Hammer & Carbboom & only drank Heed to stay away from simple sugars. I thought it was easier on my stomach. Maybe it's b/c I'm running longer & slower, but I'm able to eat more variety now.I also like Clif Blocks, Sport Beans & Sharkies.

  14. Trail Goat

    @ AnthonyP, I'm the opposite re gels thickness. Too watery and I think I'm wasting space in my pack.@ Meredith, I wonder why the gels and not the Bloks make you sick. For what I understand, most folks get sick do in part to the carbohydrates or their metabolites, which both gels and Bloks have.@ Julien, thanks!@ TrailFool. You're a regular chia head. @ RunningMtns. Thanks for sharing the information regarding carbohydrates. I agree that a little protein consumption would help during an ultra length event…. if only I would act on it. I'm not sure where I've read it, but I thought I saw some info suggesting the fat consumption during endurance events was not at all helpful in providing additional energy. Of course, ideally we've trained our bodies to burn a whole lotta body fat during ultras.

  15. Mike Blamires

    As everyone has said – great comparisons. I have never been a big fan of gels, so I usually stay away from them when I am running ultras and don't want to 'rock the boat' as it were and go for something more acceptable to my stomach and tastebuds!I have found Honey Stingers are great one toast pre/post run. When I do use them I usually go for Lucozade ones, they are sickly and unpleasent but I can use them on an empty stomach confidently. I'd be worried about how the gels taste (or at least taste to you at that moment) in the heat of the desert and how seemingly unappetising they are going to be! I know that they are a whole new taste experience when it's extra cold!cheers,Mike,

  16. Trail Goat

    Mike from the UK,I do really well with gels and had no problem with them when it was 116 F in the canyons at the Western States 100 a few years back. :-) I should have noted in the post, that despite all the technical considerations, I will heavily factor flavor in my gel choices. Fortunately, most of my favorite flavors at regular Gu or Gu Roctane flavors. I'll probably bring some earthy Clif Shot Double Espressos, as well.

  17. Michele Jensen

    I did MDS last year, and one of the major things I'd change in my food choices was to take less sweet stuff (like gels and bloks). While I could use them fine normally, the sweetness made me sick to my stomach in the desert. So – i'd just caution you to bring a variety of stuff. I was really liking the pretzels and nuts I brought, but unfortunately, i didn't bring enough since i thought i'd be ok with the gels. Just a thought.

  18. Trail Goat

    Michele,Thanks for the MdS tip. I don't plan on taking any sweet food except for when I run or immediately afterward. Lots of dehydrated meals and nuts for me. I experienced how a stage race can mess with one's appetite at the TransRockies Run this year. After Stage 5 I sat and stared at a baked potato for a good half hour before I could get myself to eat it. Fortunately, I know I've got to fuel to run, even if I don't want to.

  19. FruityRunner

    Thanks for this ~ especially the comparison of caffeine content. I noticed some of the gels I have say "2x Caffeine" but never told you just how much it actually contained. Your article helps immensely!

    I had been using mostly Clif Shots: strawberry, mocha, and mango (so sad they discontinued this flavor). However, Gu's blackberry, mint chocolate, and Roctane blueberry pomegranate are new favorites that I've worked into my rotation. I'm one of those runners who has a variety of flavors on a single run to keep the taste buds interested.

    1. Bryon Powell

      Dear Fruity Friend, I'm glad you found the comparison helpful with regard to caffeine content.

      I, too, like to switch up the gels en route. Generally, I rely heavily on vanilla or chocolate-based gels (anything from Just Plain and Gingerbread to the mocha and coffee flavors) while I like to mix in some citrus or berry flavors for a change of pace.

  20. Lindsey

    I love using Gu Gel for training and all my races. I tend to lean more towards the fruit flavors and I really like the jet blackberry and tri berry. They have never caused me to have GI distress or anything like that. The only thing is after a race I don't want to touch another gel for a couple days. Does Carbboom have a lot of flavors that aren't too sweet?

  21. Andrew

    I've only used e-gel after minimal research, I've had great results on all my training runs and in my recent finish in the headlands 50 mile race. Although it is thick, I've found that if I take a big gulp of water with a big squeeze of gel, it goes down pretty easy. There is a comparision to most products compared here, listed on the site:

  22. the running farmer

    No Meat Athlete has a recipe for homemade gel that I have used in the past. It features dates, agave syrup, coconut oil and chia seeds, taste good too.

  23. Fugazi

    Correction: Clif Shot gels have 90 mg of sodium, not 40 mg. I think there was a packaging error at first, because my gels have a sticker on it with supposedly the right amounts (i.e. 90mg of sodium).

  24. Jonathan

    Has anyone tried EFS Liquid Shot from First Endurance? I usually use mandarin flavor GU. I tried the Jet Blackberry Roctane this past Saturday and it gave me stomach issues – not sure if it was the gel itself or the fact that it was 100% humidity here in Houston. Hammer gels are too sweet. However, they are great in oatmeal.

  25. Max Wilson


    exercise causes core temperatures to rise making digestion difficult. High humidity makes it difficult for your body to cool exacerbating the condition. Max Energy liquid gel was formulated to always go down easy. All of the carbs and electrolytes can be digested through the stomach, not the small intestine, freeing all athletes from the above problems, including limited blood flow to the small intestine for digestion during exercise. Roctane has sucrose/fructose and supplements that are limited to the small intestine and you are not the first to complain. Max Energy has mellow flavors with no sweeteners or sugar. Check out .

  26. eric

    Great post! Really spells out the differences. Now, if you just had more info on taste and consistency…check out my site for more complete descriptions.

  27. Frank Lilley

    One category of comparison that no one is talking about is the gel packaging. Virtually all gel packages get an "F" as they are not eco-friendly. Tops that tear off that so many runners drop. The packs themselves will probably never degrade! Litter is becoming a huge problem . . . especially on trails. And gel packs are the primary problem.

  28. Nicki (Green Chair)

    Great to see people thinking about this. I work with Green Chair Recycling providing recycling services to many running and sports events. These gel packets just have to go in the garbage – they are too dirty for any of our facilities to accept. We often find unopened gel packets – such a waste :(

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