💡 Fuel For Thought

Why endurance isn't about picking a fuel side

At some point, every endurance athlete has wondered: Should I be burning carbs or fat?

It’s easy to fall into the “either/or” mindset, especially when social media is full of polarised takes. But endurance performance isn’t about choosing sides. It’s about understanding how both fuels work together.

Carbohydrates are your body’s fast fuel. They deliver energy quickly when the pace picks up: climbing a hill, chasing a PR, or holding tempo late in a long run. Glycogen (your stored carbohydrate) is limited, even with proper carb loading. For most athletes, it only lasts a couple of hours of hard effort.

That’s why consuming carbs during training and racing is essential: you’re topping up a fuel that empties fast.

Fat, on the other hand, provides your steady flame. It burns more slowly and supports endurance at lower intensities. Your body stores plenty of fat, even the leanest athletes have enough to run for hours, but it can’t meet high-intensity energy demands on its own.

So yes, I talk about carbohydrates a lot. Not because fat isn’t important, but because:

1. Carbs are the limiting factor. You can’t store enough to go long without fuelling.
2. They’ve been unfairly demonised. Despite what the internet says, carbs don’t derail health or performance, underfuelling does.

Think of it like a hybrid engine: fat is your efficient cruise mode, carbs are your power mode. You’re always using both, you just adjust the mix based on demand.

Endurance nutrition isn’t a carb versus fat debate. It’s a partnership.

🚀 Endurance Highlights

1️⃣ Sugar, gels and grit: Protecting your teeth during ultras

While eating sugary snacks and gels is a given during an ultra, your teeth might not appreciate it as much, especially when fuelling stretches over so many hours. This article, written by sports dentist Dr Gerard Anton, highlights why oral health plays a bigger role in endurance performance than most athletes realise.​

Frequent sugar intake, dry mouth, and mouth breathing create the perfect storm for tooth decay and gum inflammation, both of which can impact recovery, sleep, and even VO₂max. Studies show that poor gum health can lead to small but measurable decreases in aerobic capacity, while bruxism (teeth grinding caused by stress) disrupts deep sleep and recovery. Even bite imbalances can subtly affect posture and running mechanics over time.

The good news is that prevention is simple. Regular dental check-ups, rinsing with water after consuming sugary foods, maintaining a fluoride routine, and paying attention to gum health can make a significant difference.

2️⃣ The hidden impact of not drinking enough water

Water is a vital nutrient, essential for many processes including circulation, temperature regulation, and cellular metabolism. Yet, many people still don’t drink enough (myself included). This new study investigated the impact of chronic low water intake on oxidative stress and immune function during exercise. Participants were divided into two groups: low water drinkers, who consumed less than 0.5 L/day, and high water drinkers, who averaged 1.2 L/day, both levels below what would generally be recommended for active individuals.

Even at rest, those with low water intake showed higher levels of oxidative stress and a weaker antioxidant response during exercise. After a bout of intense aerobic exercise, their blood cells also showed more signs of cellular damage and inflammation. In contrast, those who drank more water were better able to neutralise free radicals and recover at the cellular level. Despite similar exercise performance, the physiological strain was much higher in the low-water group.

You don’t need to be visibly dehydrated to experience the effects of low water intake. Drinking enough water consistently, not just during training, supports your body’s antioxidant defences, immune response, and optimal function. Keep water nearby during the day and drink to thirst, no need to overdo it.

🕵🏻‍♀️ Retail Finds*

This week's product review: Bix 30 Gel

Bix recently released a new gel variety that I've been keen to try.

Features & benefits

• Facts per gel: 120 kcal, 30g carb, 300 mg sodium
• Very runny and easy to consume
• The sweetness is well-balanced with the saltiness
• Perth-owned business
• Better carb per dollar value

Things to keep in mind

• High sodium, more than most energy gels.
• Only two flavours available: Berry & Salted Strawberry

Final take

This energy gel can be a great choice for those who prefer a more liquid texture and have higher sodium needs. The carb per dollar value also makes it a good budget-friendly option.

*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​​​

Grilled Vegetable & Lentil Salad If you're keen to increase your vegetable and fibre intake, here's a tasty option for you. Use it to accompany your favourite lunch or dinner.

I'm committing to sending the most valuable endurance nutrition newsletter. I want to make sure that every piece of content you receive has information that is helpful for you and your journey to achieving your personal best.

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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