Product Review: Science in Sport (SiS) Energy Gels


Disclaimer:  I received Science in Sport (SiS) isotonic gels to review as part of being a BibRave Pro. Learn more about becoming a BibRave Pro (ambassador), and check out to review, find, and write race reviews.

Having completed 10 marathons and a number of half marathons and smaller-distance races, you would think by now I have the whole fueling thing down. Nope, wrongamundo. I STILL don’t have a clue what I’m doing. My very first race was the 2013 Chicago Marathon. I did not train, and I had never run in my life. How did I do? Believe it or not, that finish time remains my PR. I relied on my awesome pacer Tom to get me through (I finished in 2 seconds under goal), and I relied on the race organizers to determine my fueling. Yep, if the volunteers were handing out water, I drank it. Gatorade? Sure thing (even though I had never tasted it in my life)! Oh, you’re handing out chunks of bananas now? I’ll take some.

Fast-forward to today, and I’m not any better. A couple of years ago I tried a powdered supplement, which I mostly liked. But I found mixing it on the course to be cumbersome and time consuming, and I wound up with sticky fingers no matter how hard I tried to avoid it. Then two years ago at Mile 22 of the Chicago marathon, I started getting queasy. It was likely the heat, but I couldn’t stomach any more of the powdered mix, so I dumped it and finished the race on what little fuel I had left in me. I’ve been hesitant to try it again, because I’m worried that queasy feeling will forever be associated with that product.

Caffeine, anyone?

I know I have to have a strategy, so I jumped at the chance to try the SiS gels. I had no real expectations going into this trial, since I had never tried any type of energy gel before. I received a generous supply of four different products. Because I am a lover of all things coffee, I was excited to try the Double-Espresso flavor first. It had a good coffee flavor that I enjoyed, but it was a tad sweeter than I would prefer. A two ounce gel pack provides 22 grams of carbohydrates and 150 mg of caffeine, so it packs a pretty good punch! I liked this one best before my morning runs, because it definitely gave me a boost of energy.

Salted Strawberry – Yum!

The next one I tried was the Salted Strawberry flavor. Like the Double Espresso, a two ounce gel pack provides 22 grams of carbohydrates, but it also contains 54 mg of magnesium citrate, 130 mg of sodium chloride, and 18 mg of potassium chloride. Spoiler alert:  This one is my favorite! The gel was delicious and went down very easily.

After that I tried the Lemon & Mint flavor. Just like the Salted Strawberry, a two ounce gel pack provides 22 grams of carbohydrates, 54 mg of magnesium citrate, 130 mg of sodium chloride, and 18 mg of potassium chloride. I was a bit hesitant to try this flavor, because the mint didn’t sound very inviting to me. However, it tasted just like a lemon drop and I couldn’t taste the mint at all.

Apple wasn’t my favorite, but it was still good!

The last gel I tried turned out to be my least favorite – Apple. This one is the simplest of the four, with a two ounce gel pack providing 22 grams of carbohydrates, 1 mg of vitamin C, and just 10 mg of sodium. It is considered to be the most isotonic of all of them, making it the most easily digestible. I think this would be a great option for anyone who needs a quick energy boost.

Easy to carry a few in my SPIBelt!

From a practicality standpoint, I love that the gel packs are compact. I can easily fit a few of them in my SPIbelt, which I wear on all of my runs. The packs tear open easily, and I didn’t find the gels themselves to be gooey or sticky.

The big test will be this coming Sunday when I run the Napa to Sonoma Half Marathon. Since they are my favorite, I plan to bring a few of the Salted Strawberry packs to fuel me during the race.

How do you fuel your runs? Want to Science in Sports Gels for yourself? Head on over to my Instagram account @TheAccidentalMarathoner for a chance to win one of two six-packs of gels! You can also head over to the Science in Sport website and receive 25% off of your purchase using code TRYSIS.

Check out more reviews by some of my fellow BibRave Pros: Christine, Ken, Becky, Amy, Janell, Jessica, Andrea, Jenn, Alastair, Lissa, Meridith, Kim, Scott, and Christine!

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On Sunday, November 3rd, I will be running the New York City Marathon as a charity fundraiser for Team in Training, an organization that helps The Leukemia & Lymphoma Society (LLS) support cutting-edge research projects in the most promising areas of cancer research. If you’d like to contribute to my fundraising efforts, you can do so by clicking on the link below. Any donation, big or small, will help and is greatly appreciated! Want to join me? You can still register for the NYC Marathon as a charity fundraiser for Team in Training! Use code NYCBIBRAVE to have the $100.00 team registration fee waived (you still have to raise the require funds).

Click here or on the picture to get to my fundraising page!


  1. I am so excited for you this weekend! Look at you training for a race LOL. Everyone seems to love these so perhaps I should give them a try!

    1. Author

      Now let’s not get crazy here – I’ve been ‘sort of’ training for this race! I do plan to keep it up with some big fall races on the calendar!

  2. I really enjoy the Salted Strawberry flavor. The apple was my second best. I actually just ordered the vanilla and cherry flavors from the website so hope I can try those out on my next long run

    My only issue is that I wish they were a bit smaller. I hope I’m able to fit a few in my hydration belt for the Marathon!

  3. I hope your race goes well! Knowing you, you will cross that finish line with a smile no matter what 😉 I LOVED the SiS gels I got last year through Rock’nBlog. My tummy cannot tolerate the Gu gels anymore. Honey Stinger gels are better…but the SiS were fantastic for me. My tummy did not revolt, either LOL

  4. Thanks for sharing! I’ve never tried these. They sound really cool. As long as I can tolerate the taste, they’ll probably work for me!

  5. The flavors sound so good! I think I would like the salted strawberry and the lemon mint. SIS sounds like a great new energy gel to try. Thanks for the great review!

  6. That’s so exciting that you’ll be running the NYC marathon! I’ve been to spectate and it’s an awesome atmosphere. I’ve never tried SIS, but I’ll be entering your contest! @trainwithmarc_llc

  7. I completely agree about the double espresso before morning runs! The caffeine provides a noticeable boost.

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