Key takeaways
- An energy gel is a concentrated carbohydrate packet for quick fuel during endurance efforts.
- Gels help maintain blood sugar and stave off 'bonking' (glycogen depletion).
- A common guideline is roughly 30–60g of carbs per hour during long efforts — often a gel every ~30–45 min.
- Take gels with water and test them in training; they can cause stomach issues if overused or untried.
What an energy gel is
An energy gel is a small, concentrated packet of carbohydrates — usually a blend of sugars — designed to be swallowed quickly for fast fuel during prolonged endurance activity like trail running. Compact and rapidly absorbed, gels let you take in carbs on the move without stopping to chew solid food.
How they work
During long efforts your body burns through its stored carbohydrate (glycogen); when it runs low, you bonk — a sudden, profound fatigue. Gels deliver quick carbohydrate to maintain blood sugar and spare glycogen, delaying that wall and keeping you moving.
On a long run, a runner takes a gel every 40 minutes, each time washing it down with water from their hydration pack — keeping their carbohydrate intake steady so they finish strong instead of bonking in the final miles.
How to use gels safely
Aim for roughly 30–60g of carbohydrate per hour on long efforts (often a gel every 30–45 minutes), always take them with water, and pair them with electrolytes on hot or very long days. Above all, test gels in training — the concentrated sugar can upset an unaccustomed stomach, especially in ultramarathon distances.
The bottom line
Energy gels are compact, fast-absorbing carbohydrate fuel that helps endurance athletes hold off the bonk by keeping blood sugar and glycogen topped up. Aim for a steady carb intake (often ~30–60g/hour), always wash them down with water, and — crucially — test your gels and timing in training so race day brings no stomach surprises.
Frequently asked questions
What is an energy gel?
An energy gel is a small, concentrated packet of carbohydrates — typically a blend of sugars like glucose and fructose — designed to be swallowed quickly for fast fuel during endurance activity. They're compact and rapidly absorbed, making them a popular way for runners and cyclists to take in carbs without stopping to eat solid food.
How often should you take energy gels?
A common guideline for endurance efforts is to consume roughly 30–60 grams of carbohydrate per hour (more for very long ultra efforts), which often works out to one gel every 30–45 minutes. The right amount varies by person, intensity, and duration, so it's best dialed in during training rather than on race day.
Why do energy gels sometimes cause stomach problems?
Gels are highly concentrated, so taking them without enough water, taking too many, or using an untested brand can overwhelm the gut and cause nausea, cramps, or GI distress. Always take gels with water (not a sports drink, to avoid doubling up the sugar concentration) and practice your fueling in training.
Sources
- Fueling for endurance — American Council on Exercise
- Trail running nutrition — American Trail Running Association