💡 Fuel For Thought

Why science still backs carb-Loading for endurance performance

You’ve probably heard that carb-loading makes you feel heavy or sluggish before a race. Maybe you’ve even cut back on pasta or rice the night before because you didn’t want that weighed-down feeling. But the thing is that extra “weight” isn’t slowing you down, it’s fuelling you up.

When you increase carbohydrate intake in the 1–3 days before a race, your muscles ramp up glycogen storage, your body’s most efficient energy source for endurance efforts. Each gram of glycogen is stored with roughly 3 grams of water, so that small uptick on the scale is stored energy and hydration, ready to be put to work.

Studies dating back to the classic work of Bergström and colleagues in the 1960s, and confirmed by modern endurance research, show that athletes who start an event with full glycogen stores can sustain higher intensities for longer before fatigue sets in. Without it, your body shifts earlier to fat oxidation, a slower, less efficient energy system, and pace inevitably drops.

Carb-loading isn’t about stuffing yourself or chasing comfort. It’s a proven performance strategy that keeps your tank full and your pace strong.

🚀 Endurance Highlights

1️⃣ Cooling strategies that improve performance in the heat

Racing in the heat is challenging, and there’s no doubt that events are getting warmer. This new systematic review and meta-analysis looked at head, face, and neck cooling strategies and their impact on endurance performance in hot environments. The researchers analysed data from 46 studies involving over 600 athletes to identify which cooling methods actually work when it comes to maintaining performance in hot conditions.

Cooling the face, head, or neck before or during exercise can significantly improve performance, lower perceived exertion, and reduce core body temperature. Among all methods tested, neck cooling had the greatest benefit, followed by face and head cooling. Using ice towels, cooling collars, or cold water sprays proved effective, particularly in longer endurance efforts. The timing and method of cooling matter since overcooling before exercise can sometimes blunt warm-up benefits or cause discomfort.

2️⃣ Hydration and kidney health in ultra-endurance athletes

Both dehydration and overhydration can be dangerous, and achieving the right balance is often one of the hardest challenges in ultra-endurance events, especially in point-to-point races where access to fluids varies. A new study from the 2023 Western States Endurance Run (161 km) examined how hydration status impacts kidney stress during ultramarathons. Researchers collected blood and urine samples from 36 finishers before and after the race to measure kidney injury biomarkers and blood flow to the kidneys.

The study found that while kidney injury markers increased after the race, these changes were temporary and didn’t indicate permanent damage. Importantly, athletes who finished the race well-hydrated showed smaller increases in these biomarkers, suggesting a protective effect. In contrast, those who became dehydrated had greater signs of kidney stress. Interestingly, renal blood flow did not significantly change, meaning the kidneys’ circulation recovered quickly after the race.

Staying adequately hydrated, without overdoing it, appears to help protect kidney health during these extreme efforts. Practicing hydration strategies in training and adjusting for heat and terrain can make a real difference when racing long and hard.

🕵🏻‍♀️ Retail Finds*

This week's product review: Maple Movement Lemon + Salt Energy Gel

I have previously reviewed Maple Movement's Energy Gel. However, they recently released this new version that's not just maple syrup like the other one and I've been looking forward to trying it.

Features & benefits

• Facts per gel (32ml): 104 kcal, 26.8g carb, 0g protein, 0g fat, 105mg sodium
• Very runny and easy to consume
• FODMAP friendly
• Only natural ingredients

Things to keep in mind

• Sweeter than the other version
• Package is now easier to open

Final take

If you're looking for a more natural and easy to digest energy gel, this can be a suitable option. However, if you plan to get closer to 90g carb per hour mostly from this gel, it may be more challenging to tolerate it.

*Special thanks to my client Kristina from Coast To Mountain Running , who sent me a package with a wide range of products to review, including these samples.​​​​​​​​​​

👩🏻‍🍳 Kitchen Creations

Download the recipe​

No Bake Apple, Oat & Almond Butter Bars These bars are packed with energy-dense ingredients. They can be a great option as a mid-morning or afternoon snack to give you that extra quick of sustainable energy with a nice blend of healthy fats, carbs and fibre.

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Happy fuelling!

Gaby | Endurance Nutrition Specialist

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p.s. I personally read and answer your email replies.

PLUS whenever you’re ready, here are 3 ways I can help you optimise your performance:

1. Take the FREE Endurance Nutrition Audit. Not sure if your fuelling strategy is working? This quick 3-minute audit will reveal exactly where you stand and what adjustments could help you perform at your best.
2. Book a FREE strategy call. Need expert advice on your next best step? Let’s chat! In this commitment-free call, I’ll help you identify key areas to improve and map out a fueling approach tailored to your endurance goals.
3. Join the Fuel To Thrive Academy. Ready to take action? My signature program gives you the ultimate fuelling roadmap to unlock your full potential in sport and life, with proven strategies that have helped endurance athletes fuel smarter, perform better and break records.

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