Updated November 2026.
Science in Sport, usually shortened to SiS, sells sports nutrition for energy, hydration and recovery. Its range covers gels, chews, bars, drink mixes and recovery products. This SiS supplements review focuses on what the products contain, how the main ranges differ and what buyers should check before using them.
Science in Sport range at a glance
- GO Isotonic gels: a thinner gel format designed to be consumed without extra water.
- BETA Fuel gels and chews: higher carbohydrate options for longer endurance sessions.
- GO Energy bars: solid food alternatives for training and events.
- Hydration products: tablets and powders with electrolytes.
- REGO recovery products: carbohydrate and protein blends for after exercise.
The range is broad, but the labels are not interchangeable. Carbohydrate, caffeine, sodium, allergens and serving advice vary between products. Always read the exact packet rather than applying one product’s instructions to another.
GO Isotonic gels versus BETA Fuel
GO Isotonic gels are the entry point for many buyers. The current core gel supplies 22 grams of carbohydrate per serving. Its liquid texture is easier to swallow than some dense gels, although texture and sweetness remain personal preferences.
BETA Fuel is aimed at people who want more carbohydrate per serving. Current BETA Fuel gels contain 40 grams of carbohydrate. The BETA Fuel chew packaging photographed for this review states 46 grams per pack and a 1:0.8 glucose to fructose ratio. SiS pages sometimes round the chew value to 45 grams, so the packet in hand should take priority.
Caffeinated and nootropic versions need extra care. The current BETA Fuel Nootropics gel contains 200 milligrams of caffeine, and SiS advises a maximum of one per day. It is not suitable for everyone.
Current prices and availability
On the SiS European store in November 2026, GO Isotonic gel packs started at about €15. BETA Fuel gels started at about €17.50. BETA Fuel chews started at about €16.50. Bundles and member prices can reduce the cost.
Prices, pack sizes and stock vary by country. Check the official Science in Sport store before buying. Retailers may carry older packaging, so compare the nutrition panel with the current product listing.
Testing and certification
SiS states that every product batch is screened through the Informed Sport programme for substances on the World Anti Doping Agency prohibited list. Batch certificates are retained and can be requested. This is useful for tested athletes, but it does not replace checking the batch and certification record yourself.
Certification addresses banned substance testing. It does not prove that a product will improve performance or suit every stomach.
What works well
- The range offers liquid gels, chews and bars, which makes texture easier to vary.
- Clear carbohydrate amounts help users build a measured nutrition plan.
- Informed Sport batch testing is relevant for competitive athletes.
- Variety packs are a practical way to compare formats before buying a full box.
- Many products are compact enough to carry during running or cycling.
Things to note
- Flavour and sweetness are subjective. Test a small quantity first.
- Higher carbohydrate intakes need practice and may not suit every session.
- Some products contain caffeine, milk or other allergens.
- Bars need more chewing than gels and may be less convenient at higher effort.
- Online prices and formulations can change.
Practical tips
- Test every product during training before using it in an event.
- Track total carbohydrate from gels, drinks, bars and food together.
- Check caffeine across coffee, gels and other supplements.
- Carry water according to the product label and your own hydration plan.
- Replace opened or damaged packets and store products as directed.
For alternatives, compare the portable electrolyte format in our SaltStick FastChews review. The LMNT Electrolytes review covers a higher sodium drink mix. Our Marchon Endurance Fuel 30 Gel review looks at another gel format.
How to choose a SiS product
- Estimate the session duration and decide whether extra carbohydrate is needed.
- Choose a gel, chew or bar based on the texture you can comfortably use.
- Check carbohydrate, caffeine, allergens and serving instructions on the packet.
- Test one serving during training and record how it feels.
- Build the full plan from all food, drinks and supplements together.
SiS supplements photos
Frequently asked questions
Do SiS GO Isotonic gels need water?
The current product is designed to be consumed without extra water. Hydration needs still depend on the person, conditions and session.
Are all SiS products caffeine free?
No. Caffeine varies by product. Check the front and nutrition label before use.
Are SiS products suitable for tested athletes?
SiS states that every batch is Informed Sport tested. Athletes should still verify their exact batch and sporting body rules.
The Brief Review verdict
SiS offers a useful mix of gels, chews and bars with clearly stated carbohydrate amounts. The variety is its main strength. Buyers should choose by session length, desired texture, caffeine level and tolerance rather than brand alone. Start with a small selection, test it in training and follow the exact packet instructions.