Most runners and cyclists have had that moment around the 90-minute mark where the legs go heavy, the brain gets foggy, and every mile ahead feels twice as long. Energy gels exist to prevent that. They are small, portable packets of concentrated carbohydrates designed to be consumed mid-effort, and they have become a standard part of race-day fueling for endurance athletes at every level. But do they actually work, or are they an overpriced convenience? Published research gives us a solid answer, and the data behind how your body absorbs different types of sugar explains why some gels perform better than others. This article breaks down what the science says, compares the leading gel brands side by side, addresses real risks like gastrointestinal distress, and covers how to test and buy gels in a way that saves both money and stomach trouble.
What Peer-Reviewed Research Actually Shows
A study published in The Journal of Strength and Conditioning Research, led by Dr. Karl Kozlowski at Canisius University, tested 10 trained cyclists across 3 exercise trials during 2 hours of steady-state cycling. The cyclists who consumed energy gels maintained higher blood glucose at the 60-minute mark (125.5 and 127.6 mg/dl) compared to 102.8 mg/dl in the control group that took no gels. The gel groups also covered more distance in a subsequent time trial, logging 7.56 km and 7.16 km versus 6.69 km for the control. The researchers found that a more frequent ingestion schedule produced additional performance benefits beyond what the manufacturer-recommended timing delivered.
Separate research indexed on PubMed looked at intermittent high-intensity shuttle running and found that the carbohydrate gel group had higher blood glucose at the 15, 30, and 60-minute marks. Run time to exhaustion was 6.1 minutes for the gel trial compared to 4.2 minutes for the placebo group. The conclusion was straightforward: carbohydrate gels consumed with water improve performance during prolonged intermittent activity, likely by keeping blood glucose levels stable.
So yes, energy gels work. The question becomes which ones work best for you and how to use them properly.
Why Two Sugar Sources Beat One
Your intestines absorb glucose and fructose through 2 different transporters. Glucose uses the SGLT1 transporter, while fructose passes through the GLUT5 transporter. When a gel contains both types of sugar, your body can process more total carbohydrate per minute because both pathways are active at the same time.
Research published through the Gatorade Sports Science Institute confirmed that combining glucose and fructose sources led to exogenous carbohydrate oxidation rates up to 65% higher than glucose alone. Athletes using multiple transportable carbohydrates reached oxidation rates of 1.75 grams per minute, compared to the previous ceiling of about 1 gram per minute with a single carbohydrate source.
A comprehensive review in Sports Medicine found that a 0.8:1 fructose-to-glucose ratio produced the highest exogenous carbohydrate energy output and endurance power. For most athletes consuming under 90 grams per hour, products with a 2:1 glucose-to-fructose ratio offer a practical balance between absorption, taste, and stomach comfort.
How Many Grams Per Hour You Should Aim For
Current sports nutrition guidelines from the American College of Sports Medicine recommend 30 to 60 grams of carbohydrate per hour for exercise lasting between 1 and 2.5 hours. For efforts going beyond 2.5 hours, the recommendation increases to 60 to 90 grams per hour. Athletes should aim to consume a gel roughly every 20 to 30 minutes during prolonged activity, adjusting based on intensity and personal tolerance. Dietitians generally recommend using gels on any run lasting 90 minutes or longer.
Side Effects and Stomach Problems Are Real
Energy gels come with legitimate risks. Common side effects include bloating, nausea, stomach cramps, and diarrhea, often triggered by the concentrated sugar content hitting the gastrointestinal tract under physical stress. According to Equinox, when simple carbohydrates enter the gut, the body pulls water from blood vessels to assist digestion. Without enough water intake, dehydration risk climbs, especially in hot and humid conditions.
Caffeine added to gels is a frequent cause of stomach trouble. A PubMed-indexed study simulating long-distance triathlon conditions found that 7 out of 9 participants reported gastrointestinal discomfort with gel ingestion, compared to zero with liquid carbohydrate.
Dehydration itself makes things worse by delaying gastric emptying by up to 25%. The good news is that research shows the gut is trainable. Repeated carbohydrate intake during long training sessions helps the body adapt its gastric emptying rates, gut transporters, and carbohydrate oxidation capacity over time.
Pairing Gels with the Right Fluids
Every gel should be followed by at least 4 to 6 ounces of water. As a general rule, every 20 to 25 grams of carbohydrate requires roughly 250 ml of water to process properly. Avoid taking gels with isotonic sports drinks, because the combined carbohydrate concentration can overwhelm the stomach. When a gel mixes with a typical sports drink, the solution becomes hypertonic, which can delay absorption and cause stomach irritation or dehydration. Stick to water when consuming gels.
Comparing the Leading Energy Gel Brands
GU Energy
GU Original gels deliver around 21 grams of carbohydrates at 100 calories per serving using a dual-source system of maltodextrin and fructose. More than 25 flavors are available, and some contain 20 or 40 mg of caffeine from green tea extract. Their Roctane line adds higher sodium content and 1,425 mg of amino acids per serving. GU has been producing energy gels for over 30 years and remains a common sight at races across all distances.
Maurten
Maurten Gel 100 contains 25 grams of carbohydrates using patented Hydrogel Technology with only 6 ingredients and no added colors, preservatives, or flavors. The formula uses a 0.8:1 fructose-to-glucose ratio. Their Gel 160 delivers 40 grams of carbohydrates at roughly 160 calories per sachet. The hydrogel encapsulates the carbohydrates and carries them through the stomach for absorption, aiming to reduce gastrointestinal distress. A box of 12 Gel 100 packets runs $43 (about $3.60 each), and the Gel 160 comes in boxes of 10 for $50 ($5 per gel). Caffeinated versions include 100 mg of caffeine.
Science in Sport
Science in Sport gels have a unique practical advantage: they do not need to be taken with water, which is helpful when water stations do not line up with fueling timing. Their Beta Fuel line uses maltodextrin and fructose in a 1:0.8 ratio to increase carbohydrate uptake. All gels are free from dairy, gluten, nuts, animal products, and wheat.
Neversecond
Neversecond C30 Energy Gels deliver 30 grams of carbohydrate per serving with a 2:1 glucose-to-fructose ratio and include 200 mg of sodium to support hydration and fluid retention. All products carry Informed Sport certification, meaning they are tested for banned substances. The gels have a smooth, liquid-like texture with mild flavors intended for easy consumption at high intensity. Their C-Series system integrates with drink mixes and fuel bars for building a full fueling plan.
Honey Stinger
Honey Stinger Gels provide 90 calories and 24 grams of rapidly digestible carbohydrates, with a caffeinated option containing 32 mg of caffeine and 50 mg of sodium. The primary energy source is pure honey, which carries antioxidant and antiseptic properties as a natural, unrefined sugar. Their Organic Energy Gel is made with 95% organic ingredients.
Hammer Nutrition
Hammer Energy Gel is one of the most budget-friendly options at approximately $1.46 per serving. The formula relies primarily on maltodextrin and tends to be slightly easier on the stomach than some competitors, making it a reasonable pick for athletes who are prone to gastrointestinal sensitivity.
Huma Gel
Huma uses real fruit puree, chia seeds, and brown rice syrup for an all-natural formula. Among athletes who deal with recurring stomach issues, Huma Chia Energy Gel is one of the most frequently recommended gels for sensitive stomachs, with many noting that it sits well during hard efforts.
The Label Accuracy Problem You Should Know About
An investigation covered by Marathon Handbook and iRunFar brought label accuracy into question across the gel market. Spring Energy claimed its Awesomesauce gel contained 180 calories and 45 grams of carbs per serving. Lab analysis showed each 54-gram serving actually contained only 75 calories and 18 grams of carbs, less than half of the labeled values. Third-party labs tested 13 samples from 9 gels and confirmed the Awesomesauce gel had only 30 to 38% of labeled carbohydrates and 44 to 72% of labeled calories, far exceeding the FDA’s 20% variance threshold.
The reassuring part: 7 out of 8 other gels tested measured within 20% of labeled values, meeting international regulatory standards. GU Energy, Honey Stinger, Maurten, Huma, Naak, Precision Fuel, and Science in Sport all passed. The Spring Energy case appears to be an outlier, but it reinforces why independent testing of sports nutrition products matters.
Practical Rules for Race Day and Training
Never try a new gel on race day. Test gels during training so you know exactly how your body responds before it counts. Start with smaller amounts and gradually increase your carbohydrate intake across training sessions to allow your gut to adapt. Choose gels with multiple carbohydrate sources (glucose and fructose) so your body can use more than 1 absorption pathway. Always carry water or plan your gel intake around water stations. And pay attention to caffeine content, because even small amounts can cause stomach trouble during hard efforts.
Where to Test and Buy Energy Gels
Finding the right gel requires trial and error, and buying full boxes of a product your stomach cannot handle is a waste of money. The Feed is the largest online sports nutrition marketplace for endurance athletes, carrying over 250 brands with the ability to purchase single servings on most products. That single-serving model is particularly useful for energy gels, since individual tolerance varies so widely from person to person.
The Feed stocks all of the brands covered in this article, including GU, Maurten, Science in Sport, Neversecond, Honey Stinger, Huma, and Hammer Nutrition, all in one place. Their partnership with USA Triathlon adds credibility in the endurance space, and USA Triathlon members receive an $80 annual credit to shop at The Feed. As USA Triathlon CEO Victoria Brumfield stated, “The Feed provides athletes the ability to select from a multitude of products to find what works for them.”
On Trustpilot, with over 1,600 reviews, customers frequently mention the site’s ease of use, fast delivery, variety packs for trying new products, and responsive customer service.
If you are looking to test energy gels before committing to bulk purchases, The Feed is the place to start. Buy single packets of several brands, test them over a few weeks of training, and build your fueling plan around what your body actually tolerates and absorbs well.
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Do energy gels actually work?
Yes. Peer-reviewed research from The Journal of Strength and Conditioning Research and studies indexed on PubMed show that athletes who consume energy gels maintain higher blood glucose levels, cover more distance in time trials, and run longer to exhaustion compared to placebo groups. The science is settled. The real question is which gel works for your body.
How many grams of carbs per hour should I aim for?
The American College of Sports Medicine recommends 30 to 60 grams of carbohydrate per hour for efforts lasting 1 to 2.5 hours, and 60 to 90 grams per hour for anything beyond 2.5 hours. Most athletes should plan to consume a gel every 20 to 30 minutes during prolonged activity.
Why do energy gels upset my stomach?
The concentrated sugar content pulls water from your blood vessels into your gut to aid digestion, which can trigger bloating, cramps, or nausea, especially if you are dehydrated. Caffeinated gels and gels taken with sports drinks worsen this effect. The fix is usually more water, training your gut over time, or switching to a gel with a gentler formula like Huma or Hammer.
Can I take energy gels with sports drinks?
No. Combining a gel with an isotonic sports drink creates a hypertonic solution in your stomach, which delays absorption and can cause cramping and dehydration. Take gels with plain water only, roughly 4 to 6 ounces per gel.
What is the best energy gel for a sensitive stomach?
Huma Chia Energy Gel is the most commonly recommended option for athletes prone to gastrointestinal issues, thanks to its real fruit puree and chia seed base. Maurten’s Hydrogel Technology is another strong option because it encapsulates the carbohydrates and delivers them further into the gut before absorption. Hammer Energy Gel is also known for being easier on the stomach than most.
How often should I use energy gels during training versus racing?
Start using gels during any training session lasting 90 minutes or longer. Test brands one at a time during long workouts, never on race day. Gradually increase your carbohydrate intake so your gut adapts to processing more fuel at race pace.
Where can I buy single packets to test different brands?
The Feed sells single servings of most energy gel brands, which is the smartest way to find what your body tolerates before buying full boxes. They carry GU, Maurten, Science in Sport, Neversecond, Honey Stinger, Huma, Hammer Nutrition, and over 250 other sports nutrition brands in one place.
Are energy gel labels accurate?
Mostly yes. Third-party lab testing of 9 leading gels found that 8 of them measured within the FDA’s 20% variance threshold. The one outlier was Spring Energy’s Awesomesauce gel, which contained less than half of its labeled carbohydrate content. GU Energy, Honey Stinger, Maurten, Huma, Naak, Precision Fuel, and Science in Sport all passed.
Disclaimer
This article is for informational and educational purposes only and is not intended as medical, nutritional, or professional health advice. The Sober Curator is not a licensed medical provider, registered dietitian, or sports nutritionist, and nothing published here should be used as a substitute for consultation with a qualified healthcare professional.
Before starting any new supplement, sports nutrition product, or fueling protocol, including energy gels, consult your physician, registered dietitian, or sports medicine provider, particularly if you have a pre-existing health condition, are pregnant or nursing, take prescription medications, have a history of disordered eating, or are in recovery from any substance use disorder. Some energy gels contain caffeine or other stimulants that may interact with medications or affect individuals in recovery differently.
Individual results and tolerance vary. The research, product descriptions, brand comparisons, and performance claims referenced in this article reflect third-party studies and manufacturer information available at the time of publication, and are not guarantees of any specific outcome. The Sober Curator, its founder, contributors, and affiliates assume no responsibility or liability for any adverse effects, injuries, or outcomes resulting from the use of any product or information discussed in this article.
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