In recent years, endurance athletes have seen a resurgence in high-carb fueling strategies, especially among trail and ultrarunners. While low-carb, fat-adapted approaches once stole the spotlight, many runners are returning to carbohydrates as their primary energy source for long efforts. But as nutrition trends shift, so do the demands on hydration and even the gear you carry on the trail.
Let’s break down how increasing carb intake on the trail impacts your hydration strategy and what that means for your gear.
The Hydration-Nutrition Connection
Carbohydrates are not just fuel, they’re also water magnets. For every gram of glycogen stored in your muscles, your body holds about 3–4 grams of water. This means that when you’re increasing carb intake before or during a run, your body’s water needs increase as well. According to Trail Runner Magazine’s hydration guide, water balance is tightly linked with energy metabolism, especially when carbs are your primary fuel.
So, if you’re pounding gels, chews, or drink mixes, you’re not just increasing calorie intake. You’re also raising the amount of water your body needs to properly digest and metabolize that fuel.
A common misconception is that hydration is only about replacing sweat. While sweat rate is important (and varies with temperature, altitude, and effort), fueling with more carbohydrates changes the equation.
As coach David Roche explains, runners should aim for about 16 to 24 ounces of fluid per hour in most trail scenarios. But if you’re taking in more carbs, especially concentrated sources like gels or sports drinks, fluid needs may rise toward the upper end of that range or beyond. This helps maintain osmotic balance and avoid gastrointestinal distress.
A good rule of thumb: the more carbs you consume, the more water you need to consume with them. If you’re using a gel every 30–45 minutes, chase each one with several ounces of plain water, not just electrolyte mix.
Gear Implications: Time to Reassess Your Setup
So how does this all affect what you carry on your run?
Increased Fluid Capacity
Higher-carb fueling means you may need to carry more water. That handheld bottle or 1-liter vest reservoir might not cut it for longer efforts. Consider:
- Dual soft flasks (with one reserved for water)
- A larger reservoir for long runs, or additional soft flasks
- Filter-cap bottles if you’re running near natural water sources
Separate Fuel and Fluids:
Mixing concentrated carbs into your only water source can be a recipe for GI distress if you can’t balance it with plain water. Carrying separate bottles, one with electrolytes/carbs and one with plain water, gives you flexibility.
Smarter Storage:
More fuel means more packaging. With higher-carb strategies, you’ll likely carry more gels or chews, so a vest or belt with easy-access pockets becomes more important for mid-run refueling.
Weight Trade-offs:
Carrying more water and fuel adds weight. But bonking or cramping from under-hydrating or under-fueling is worse. If you’re moving toward higher-carb nutrition, it’s worth training with the added load to find what’s comfortable for your pace and distance.
Your Final Takeaways
As carbohydrate-based fueling regains popularity among endurance athletes, it’s critical to adapt hydration strategies accordingly. Carbs help you go faster and longer, but only if your hydration keeps pace. Whether you’re training for your first 50K or pushing new mileage limits, your nutrition plan should include a solid hydration strategy, and your gear should support both.
The bottom line: Fuel and hydration are inseparable. As one evolves, the other must follow, and your trail gear is the bridge between them.
Ready to dial in your own strategy? Start by experimenting with your carbohydrate intake on training runs and pay attention to how your hydration needs to adjust. Test your hydration gear alongside it to ensure it supports your fueling plan comfortably and effectively. With the right combination, both your body and your trail times will benefit.
Want to Go Deeper on Hydration Tools?
Now that you understand how fueling impacts hydration, take the next step and click here to explore how different bottle types, soft flasks, hard bottles, sizes, and materials can support your strategy.
