Picture this: A Tour de France rider, deep in the Alps on a brutal mountain stage, steadily sipping and chewing his way through the caloric equivalent of eight to ten bananas every single hour. Professional cyclists and marathoners are now routinely hitting 90–120 grams of carbohydrates per hour (sometimes more) during races — a dramatic leap from the 30–60 g/h recommendations that dominated endurance sports just 15 years ago.

This isn’t hype or Instagram fads. It’s a carb revolution backed by hard physiology, real-world race data, and cutting-edge research. Elite athletes have discovered that strategic high-carb fueling doesn’t just prevent bonking — it unlocks measurable performance gains, faster recovery, and the ability to sustain race pace longer in multi-hour, multi-day efforts. But it’s not without trade-offs. Let’s dive into the science, the why, the pros and cons, and how accessible products like Xendurance Fuel-5 are helping athletes execute this strategy cleanly and effectively.

From “Carbs Are the Enemy” to “More Is Better”: The Evolution of Fueling

For decades, endurance nutrition followed a cautious playbook. Early studies (pre-2010) showed that 30–60 g/h of carbs during exercise could maintain blood glucose and spare muscle glycogen. Guidelines from the American College of Sports Medicine and others settled on that range for events over 60–90 minutes.

Then the data shifted. Asker Jeukendrup, one of the world’s leading sports nutrition researchers, demonstrated that using multiple transportable carbohydrates — glucose + fructose in roughly 2:1 or 1:0.8 ratios — could dramatically increase exogenous carb oxidation (how much of the ingested fuel your muscles actually burn). The gut’s two separate transporters (SGLT1 for glucose, GLUT5 for fructose) work in parallel, allowing absorption rates to climb from ~60 g/h to 90 g/h or higher without overwhelming the system.

Observational data from pro cycling tells the story: On-bike carb intake in WorldTour riders jumped from ~23 g/h in the late 1990s to 64 g/h by 2008, then to an average of 91 g/h (range up to 119 g/h) in recent Vuelta a España stages. Today, top teams target 90–120 g/h on demanding days, with some pushing beyond on the hardest climbs.

Runners followed suit. A 2025 study on elite male marathoners (VO₂max ~70.6 ml/kg/min) tested 60, 90, and 120 g/h during 2-hour treadmill runs. The athletes oxidized significantly more of the ingested carbs at the highest dose, becoming more metabolically efficient even though some experienced GI discomfort.

The Science: Why Higher Carb Intakes Deliver Results

The benefits go far beyond simply “not running out of gas.”

1. Sustained Energy & Glycogen Sparing

During prolonged high-intensity efforts, carbs become the dominant fuel. At marathon pace, elites burn 50–65% carbs even when fat-adapted. Ingesting 90–120 g/h provides an external supply that keeps blood glucose stable and reduces reliance on finite muscle and liver glycogen stores.

2. Improved Recovery in Stage Races

In multi-day events like the Tour de France or ultra marathons, high in-race carbs reduce the post-stage energy deficit. Riders can hit 6,000–8,000+ kcal/day without as much gut stress afterward, preserving performance for the next stage. Research on mountain marathoners showed 120 g/h reduced exercise-induced muscle damage markers compared to lower doses.

3. Gut Training Makes It Possible

The gut is trainable. Studies show 2–10 weeks of deliberate high-carb intake during training sessions increases transporter density and absorption capacity, slashing GI distress. Elite teams now treat gut training like interval sessions — non-negotiable.

4. Central Nervous System Boost

Even small amounts of carbs (mouth rinses) improve perceived effort via oral receptors. At 90–120 g/h, the constant fuel signal keeps the brain happy and motivated.

Daily totals have shifted too: Pros now aim for 8–12 g/kg bodyweight on heavy training/race days, with much of that timed around and during sessions.

The Positives and the (Very Real) Negatives

Positives are clear for elites who can tolerate it:

• Faster times in long events.
• Better back-to-back day performance.
• Reduced low-energy availability risks that plague many endurance athletes.
• Potential for higher training quality overall.

Negatives exist and explain why this isn’t blanket advice for every weekend warrior:

• GI Distress: Still the #1 limiter. Even with gut training, 120 g/h can cause bloating, cramps, or worse if not practiced.
• Metabolic Trade-offs: Chronic very-high-carb diets may suppress fat oxidation long-term and accelerate glycogen depletion in some scenarios if fueling isn’t periodized.
• Practicality & Cost: Gels, drinks, and bars add up — financially and logistically.
• Individual Variation: Not every athlete oxidizes carbs at elite rates. Genetics, sex, and microbiome play roles. Some recent work questions whether 120 g/h actually spares endogenous glycogen better than 90 g/h in all contexts.

The consensus from researchers like Jeukendrup and Podlogar in 2025–2026: 90 g/h is the evidence-based sweet spot for most; 120 g/h is an elite tool best reserved for the hardest efforts after proper preparation.

Xendurance Fuel-5 – A Premier, Clean Carb Fuel for the High-Intake Era

As athletes chase these higher targets, the quality of the carbs matters. Enter Xendurance Fuel-5, a standout multi-source carbohydrate drink mix designed specifically for sustained endurance efforts.

Fuel-5 delivers approximately 35 g of carbs per two-scoop serving from four carefully chosen sources — including organic sweet potato for slow-release energy — plus electrolytes and B-vitamins (B6 and B12) to support energy production and recovery. The berry flavor is clean and non-cloying, making it easy to sip hour after hour without palate fatigue. It’s plant-based, free of artificial junk, and formulated to work with the gut rather than against it — exactly what high-volume carb strategies demand.

Many elite endurance athletes and serious age-groupers have turned to Fuel-5  since 2010 because it provides that perfect mix of fast- and slow-digesting carbs while delivering lactate-buffering support and hydration in one package. It’s not just fuel — it’s performance nutrition engineered for the reality of modern racing.

Practical Takeaways for Your Next Long Effort

• Start conservative: Aim for 60–90 g/h and build up with gut training sessions.
• Mix sources: Use drinks, gels, chews, and real food (rice cakes, bananas) in a 1:0.8 glucose:fructose ratio when possible.
• Practice, practice, practice: Treat race fueling like any skill — test it weekly.
• Personalize: Track how you feel at different intakes. Tools like continuous glucose monitors can help.

Pair smartly: Consider products like Fuel-5 for longer sessions where clean, sustained energy is key.

The Bottom Line: Fuel Like the Elites

The carb revolution isn’t about eating more sugar for fun — it’s about precision fueling that matches the incredible demands elite runners and cyclists place on their bodies. Science has caught up to what the best athletes already knew: when the engine is running at race pace for hours, carbs are rocket fuel.

Whether you’re chasing a Boston qualifier, a gran fondo PR, or simply want to feel strong on your long weekend ride, the message is clear: Train your gut, choose high-quality sources, and fuel aggressively when it counts. The era of under-fueling is over. The era of smart, science-backed high-carb performance is here.