Ethan BrooksBy Ethan Brooks

Updated November 2026

SiS Beta Energy Gels are carbohydrate gels built around a blend of glucose and fructose sources, designed to deliver fast fuel during runs lasting longer than about 60 to 75 minutes. For most runners, the right approach is to take one gel roughly every 30 to 45 minutes, with water, and to test the plan in training before race day. Gut comfort depends as much on timing and fluid as on the gel itself.

Why SiS Beta Energy Gels Matter for Long Runs

Your body stores roughly 300 to 500 grams of carbohydrate as glycogen in muscle and liver, depending on size, training status and diet. A marathon pace effort can burn through that reserve well before the finish. Energy gels exist to top up carbohydrate intake while you run, which helps delay the fatigue that comes from low blood sugar and depleted glycogen.

Shopping for one? See our guide: SiS GO Energy Gels Review: Features and Performance.

The “Beta” name refers to the formulation approach used across the SiS Beta line, which pairs multiple carbohydrate types so the gut can absorb more total carbohydrate per hour than a single sugar typically allows. Product labels list the exact grams per gel, so check the packaging for your specific flavor rather than relying on general figures.

Factors That Affect How Well a Gel Works for You

Several variables determine whether a gel helps or causes problems:

  • Total carbohydrate per hour. Most runners tolerate 30 to 60 grams of carbohydrate per hour, with trained guts sometimes handling more. Multi-sugar formulas are generally used to support higher intakes.
  • Fluid intake. Gels pull water into the small intestine. Taking them without enough water is a common cause of cramping and nausea.
  • Intensity. Blood flow shifts away from the gut during hard efforts, so gels are often easier to digest at steady, easy-to-moderate pace.
  • Training exposure. Practicing with the exact product in long runs builds tolerance. Introducing a new gel on race day is a frequent source of problems.
  • Caffeine and flavor. Some SiS variants contain caffeine. Check the label before use, especially late in the day or for runners sensitive to stimulants.

What to Do If Gels Upset Your Stomach

Stomach issues are common in endurance sport and usually trace back to fueling mistakes rather than a bad product. Work through these adjustments one at a time so you can identify the cause:

  1. Reduce the number of gels per hour, or space them further apart.
  2. Take each gel with 100 to 150 milliliters of water, unless your race or product guidance says otherwise.
  3. Start fueling earlier, around the 30 to 45 minute mark, rather than waiting until you feel depleted.
  4. Test the same flavor and timing in at least two or three long training runs before race day.
  5. If symptoms persist after adjusting, consult a sports dietitian or your physician, particularly if you have a history of gastrointestinal conditions.

Practical Tips for Using SiS Beta Energy Gels

  • Write down your gel schedule for each long run so you can repeat what worked.
  • Carry gels in a pocket or race belt that keeps them accessible and prevents them from heating up or leaking.
  • Open the packet fully and squeeze steadily; partially opened gels are harder to finish quickly on the move.
  • Pair gels with the drink available on course, but check whether that drink contains carbohydrate, since doubling up can exceed your target.
  • Keep one gel as a backup for the final third of a race if your planned schedule gets disrupted.

What We’d Use

For runners who want a direct starting point, the SiS Beta Fuel Energy Gel line is the most relevant product family to test first, choosing a flavor you already tolerate. View on Amazon

If you prefer a simpler carbohydrate profile during training, a standard SiS GO Energy gel is useful for comparing how your stomach responds to single-source versus multi-source formulas. View on Amazon

How many SiS Beta Energy Gels should I take in a marathon?

Most marathoners plan around four to six gels over the full distance, starting after the first 45 to 60 minutes. Adjust based on your training tests and the carbohydrate content printed on the package.

Can I take SiS Beta Energy Gels before a run?

Some runners use a gel 10 to 15 minutes before starting, but this can cause a blood sugar rise and stomach discomfort for some people. Test it in training first. For guidance, see When to Take SiS Energy Gels: A Timing Guide for Runners (2026).

Do SiS Beta Energy Gels contain caffeine?

Not all variants do. Check the specific flavor label. For a comparison of caffeinated options, see SiS GO Energy + Caffeine Gel Review: Sis Energy Gels Caffeine Pros and Cons.

How do SiS gels compare with other brands?

Formulas differ in carbohydrate ratios, sodium content and flavor. For a side-by-side look, read SiS Energy Gels vs Maurten Gels: Which Should You Choose? (sis Energy Gels Uk).

Should I take gels with water or sports drink?

Water is the usual pairing with gels. If you use a sports drink, account for its carbohydrate so you do not overshoot your hourly target. Consult a sports dietitian for a personalized plan if you have specific medical concerns.

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.