Ethan BrooksBy Ethan Brooks

Updated November 2026

Low sugar energy gels can work well for runners, but only if they still deliver enough carbohydrate to fuel your effort. A gel with little or no sugar is usually built around alternative carbs, such as maltodextrin or sugar alcohols, or it may be designed for low-carb and keto plans. The key question is whether the gel supplies roughly 20 to 30 grams of carbohydrate per serving, and whether your gut tolerates it at race pace.

Why Sugar Level Matters for Endurance Fueling

Your muscles rely on carbohydrate as a fast fuel once efforts climb above easy aerobic pace. Most runners can absorb roughly 60 grams of carbohydrate per hour when the source is a mix of glucose and fructose, and around 30 to 60 grams per hour when using a single source. A gel that is low in sugar but also low in total carbohydrate can leave you underfueled by the second hour of a marathon.

That is why the label needs more than a quick glance. A gel can be marketed as “low sugar” while still containing a meaningful amount of maltodextrin, which is a rapidly digested glucose polymer. Our article on Why Is There Maltodextrin in Energy Gels? Purpose and Trade-Offs explains why manufacturers use it and what it means for stomach comfort.

Factors That Decide Whether a Low Sugar Gel Works for You

Three factors matter most when you compare options:

  • Total carbohydrate per serving. Check the grams of carbs, not just the grams of sugar. Many runners aim for 20 to 25 grams per gel.
  • Carbohydrate type. Glucose, maltodextrin and fructose are absorbed differently. Sugar alcohols such as erythritol add few usable calories and can cause cramping or diarrhea in some people.
  • Fluid and water content. Gels need water to move through the stomach. Take them with water, not sports drink, unless the label says otherwise.

Keto-oriented gels deliberately keep carbohydrate low. They suit fat-adapted athletes training at easy pace, but they are usually not enough for hard race efforts. If you are comparing options, our roundup of Top 5 Best Low Carb Energy Gels Compared for Keto Runners looks at how these products differ in carbohydrate content.

How to Test and Use Low Sugar Gels Safely

Never try a new gel for the first time on race day. Test it during your long runs, using the same timing and fluid you plan to use on race morning.

  1. Read the label and calculate grams of carbohydrate per hour based on how many gels you plan to take.
  2. Start with one gel at about 45 minutes into a long run, then add another at 90 minutes if you feel fine.
  3. Take each gel with 4 to 6 ounces of water unless the manufacturer says otherwise.
  4. Note any bloating, cramping or urgency. If symptoms appear, switch to a gel with a different carbohydrate source.
  5. Carry a backup you have already tested, so you are not forced to use an unfamiliar product mid-race.

If you have diabetes, a history of gastrointestinal problems, or you are following a medically supervised diet, consult a doctor or sports dietitian before changing your fueling strategy.

What We’d Use

For runners who want lower sugar without giving up usable carbohydrate, look for a gel that pairs maltodextrin with a moderate amount of fructose. Many people find these easier on the stomach than gels built on sugar alcohols. View on Amazon

For keto-style training runs at easy pace, a gel with very low total carbohydrate can fit the plan. Use it only for low-intensity sessions. View on Amazon

FAQ

Are low sugar energy gels as effective as regular gels?

They can be, if they still provide roughly 20 to 30 grams of carbohydrate per serving. A gel with very little carbohydrate will not fuel hard efforts as well as a standard gel.

Do sugar-free gels cause stomach problems?

Some do, especially those using sugar alcohols such as erythritol or xylitol. Test any new gel during training before using it on race day.

Can I take low sugar gels during a marathon?

Yes, provided you have tested the product and you are meeting your hourly carbohydrate target. Take each gel with water and monitor how your stomach responds.

Ready to choose one?

Ethan Brooks

About Ethan Brooks

Ethan Brooks is part of our editorial team and reviews and edits our marathon & half-marathon guides, checking product details against manufacturer specifications and owner feedback.