Energy gels deliver concentrated carbohydrate that raises blood glucose and feeds working muscles and the brain, with most packets providing 21–23 grams of carbs.
For the full breakdown, see our best Cheap Energy Gels guide.
A gel is a small, honey-like packet holding roughly 65–70% carbohydrate — about 65–75 grams per 100 milliliters. That concentration travels in a jersey pocket and delivers fuel without a chewable bar or bulky drink. The trade-off: it needs water to go down well.
Once swallowed, the carbohydrates break down into glucose and other absorbable sugars. Blood glucose rises, and muscles and the central nervous system get fuel. Gels also top up glycogen, the limited carbohydrate store your muscles and liver keep on hand — a store that runs low during long efforts.
What follows covers the transport biology that decides how much you can absorb, the hourly targets for your event length, and the mistakes that send runners reaching for the nearest porta-potty.
What Happens Inside Your Gut When You Take One?
Carbohydrate crosses the intestinal wall through specific transporter proteins, and which sugar you swallow decides which door it uses. Glucose-based carbohydrate — maltodextrin, glucose polymers, sucrose — moves mainly through sodium-glucose cotransporter 1, or SGLT1. Fructose takes a separate pathway.
That matters because SGLT1 saturates. Above roughly 60 grams of glucose-based carbohydrate per hour, the transporter becomes the bottleneck and extra gel just sits in the gut. Pairing glucose or maltodextrin with fructose spreads the load across two pathways and lifts total absorption and oxidation.
A second effect has nothing to do with absorption: carbohydrate sensors in the mouth fire signals to the brain the moment gel hits your tongue. That is why rinsing carbohydrate around your mouth and spitting it out can help during short, hard efforts, per the Australian Institute of Sport.
GU Energy Labs lists maltodextrin and fructose as the carbohydrate sources in its Original Energy Gel, which the company says carries 21–23 grams of carbohydrate per packet alongside caffeine options. Reading the label beats assuming — packet sizes and carb counts vary by brand and flavor.
How Much Carbohydrate Do You Actually Need Per Hour?
The right dose tracks your event length. Under 45 minutes, carbohydrate supplementation generally is not needed. From one to two and a half hours, the AIS target is 30–60 grams per hour. Past two and a half to three hours, intake may climb toward 90 grams per hour — preferably from a glucose-plus-fructose product.
- Under 45 minutes: no supplemental carbohydrate required; a mouth rinse is an option for sustained high-intensity work of 45–75 minutes.
- 1–2.5 hours: 30–60 grams per hour.
- Over 2.5–3 hours: up to 90 grams per hour, using multiple transportable carbohydrates.
- Above 60 grams per hour: do not attempt this on glucose-based carbohydrate alone.
Weigh packets instead of eyeballing “servings.” Grab the number off the back of the packet, do the division once, and write the schedule on your hand.
| Event Length | Carbohydrate Target | Gel Strategy |
|---|---|---|
| Under 45 minutes | None needed | Skip it; mouth rinse is optional |
| 45–75 minutes, high intensity | Small amounts or mouth rinse | Partial gel, or rinse and spit |
| 1–2.5 hours | 30–60 g per hour | Roughly 1–2 packets per hour, with water |
| Over 2.5–3 hours | Up to 90 g per hour | Glucose-plus-fructose products, spread out |
| Any duration, first attempt | Your practiced dose | Never a new flavor or formula on race day |
How Do You Take A Gel Without Stomach Trouble?
Chase every concentrated gel with water. The AIS is direct: water lowers the carbohydrate concentration in your stomach, speeding emptying and addressing hydration as a separate job. Taking a gel dry, or with a sports drink that is already carbohydrate-heavy, stacks sugar on sugar and is the fastest route to cramps and nausea.
Start early rather than waiting for fatigue, nausea, or dizziness — late signals that you are already behind on fuel. Spread intake across the event instead of slamming several packets at once, and treat gels as part of your hydration plan, never a replacement.
Two assumptions quietly wreck race days. Not every gel contains electrolytes or caffeine, and not every gel carries the same carbohydrate load — check each label. The other: your body will cooperate with a product it has never met. Practice the exact gel, timing, and fluid volume in training; competition is the wrong laboratory.
If a medical condition affects your blood sugar, that conversation belongs with your clinician. Runners who want to test options without overspending can compare prices in this roundup of cheap energy gels before committing to a flavor mid-race.
Common Questions
Do energy gels give you energy instantly?
No. A gel’s carbohydrate must be digested and absorbed before it reaches your muscles, and part of the boost comes from carbohydrate sensors in your mouth signaling the brain. Real fuel delivery takes time, which is why early, steady intake beats a desperate gel at mile twenty.
Can you take energy gels without water?
You can, but you should not. Concentrated gels need fluid to dilute the carbohydrate load in your stomach. Water speeds gastric emptying and separates fueling from hydration. Taking gels dry, or alongside a carbohydrate-heavy sports drink, raises the odds of stomach discomfort.
How many energy gels should you take per hour?
It depends on the packet’s carbohydrate count and your event length. A 22-gram gel means roughly two packets per hour to hit a 45-gram target. Add up the grams, not the packets, and never introduce a new product during competition.
Sources
- Australian Institute of Sport. “How and when do I use it?” Source for hourly carbohydrate targets and pre- and during-exercise gel use.
- Australian Institute of Sport. “Sports gels.” Source for gel carbohydrate concentration, transporter pathways, and hydration guidance.
- GU Energy Labs. “Original Energy Gel.” Source for the 21–23 g carbohydrate per packet figure and maltodextrin-fructose formulation.