Carb loading: how to get it just right before a marathon

Nailing your carb loading before a marathon can be the secret weapon that turns a tough race into a strong finish. How do you get the right carb balance right though, and what pitfalls should you look out for?

There are a few things to consider, such as not overdoing it which can lead to sluggishness, or underdoing it which ends with you hitting the dreaded wall.

Here’s what you need to know if you are looking to perfect the carb-loading balance right before a marathon.

What is carb loading — and why does it matter?

To start, let’s look at why it matters. Carb loading is a nutrition strategy that increases the amount of glycogen stored in your muscles and liver. For runners tackling anything over 90 minutes — like a marathon — it can be the difference between steady pacing and total failure.

Typically, you’ll start increasing your carbohydrate intake 2 – 3 days before race day. This helps delay fatigue, improve endurance, and preserve muscle function over long distances. But keep in mind: not all carbs are created equal. You want easily digestible, clean sources that deliver energy without digestive distress.

Finding the magic formula

The good news is that today you’ll find a wide range of sports nutrition products that are specifically crafted with the marathon runner in mind. These products, tried and tested over many years, give your body the required balance of nutrients and minerals as you put your carb-loading cycling into gear. Pick the wrong product, though, and your gut will pay for it.

It’s all about finding a trusted product that thousands of other athletes swear by. Enter Fixx Nutrition and a range of products created by marathon runners for marathon runners.

Fuel X: A gut-friendly carb blend for marathon week

For many runners, especially those with sensitive stomachs, traditional carb-loading methods (think bowls of white pasta) can lead to bloating or leaky gut symptoms. That’s where Fuel X steps in.

Fuel X features a blend of fast and slow-release carbohydrates carefully combined for sustained energy without gut discomfort. It’s packed with all-natural ingredients and includes key electrolytes like sodium and potassium to support hydration. The formula is intentionally gut-friendly, making it ideal for runners who struggle with digestion during longer efforts.

Use it to top up glycogen stores in the two days before your marathon, sipping it between meals or during light shakeout runs.

Fuel X Pro: going beyond carbs with magnesium and amino acids

If you’re looking to get even more from your fuelling, Fuel X Pro offers a next-level option. It contains the same carb blend as Fuel X, but with the added benefit of magnesium and amino acids—two ingredients that help reduce muscle fatigue, support recovery, and assist with nerve function.

Magnesium, in particular, plays a key role in preventing electrolyte imbalance in endurance sports. It supports optimal hydration and muscle contraction — critical on marathon day when sweat rates are high. Amino acids also help preserve muscle during extended periods of exercise, supporting peak performance in female athletes who may be more susceptible to muscle breakdown.

Cramp management: Salt Tablets vs CrampFix vs Pickle Juice

Another product that athletes around the world swear by is CrampFix, a formula designed to tackle the dreaded cramp. How does CrampFix differ from salt tablets and pickle juice, though?

• Salt tablets replace sodium lost through sweat, but they take time to absorb and don’t always contain the full spectrum of electrolytes.

• Pickle juice is often used by athletes to relieve cramps by stimulating the nervous system through vinegar’s sharp flavour. But it’s bulky and not the most practical on course.

• CrampFix is a concentrated formula that targets the same nerve pathways as pickle juice, but in a convenient 15ml shot. It works rapidly, helping to relieve cramps almost instantly, and is backed by clinical studies.

So, does pickle juice stop muscle cramps? It can — but CrampFix does it faster and more efficiently. If you’ve ever wondered does salt cure cramps, the answer is: only if the cramp is caused by sodium loss, and it usually needs to be taken before the cramp begins.

The final word on carb loading before a marathon

Effective carb loading for runners isn’t about eating as many carbs as you can stomach. It’s about fuelling with the right types of carbohydrates, combining them with balanced electrolytes, and supporting your body’s needs before and during the race.

Fixx Nutrition’s Fuel X, Fuel X Pro and Endurance Gels offer smart, natural, gut-friendly solutions for every stage of your marathon journey. And if cramps hit hard, keep CrampFix close by.

Because when the training is done, the race comes down to one thing: fuelling right.