HYROX Race-Day Fuel: What to Eat, When to Take a Gel, and How Much Caffeine

You can nail every sled push and still blow up on run seven if you walk in under-fuelled. The good news: HYROX nutrition isn’t complicated. Here’s a plan built from sports scientists’ guidance, the rules on carrying gels, and the products worth packing.

This guide uses advice from Precision Fuel & Hydration sports scientist Tash Cooper-Smith and FuelHub nutritionist Edward Mather in Men’s Fitness, plus the rulebook. This is general information, not personal medical advice; if you have a health condition, check with a professional. Our Amazon links are affiliate links; see our affiliate disclosure.

The day before: top up the tank

Your muscles store roughly 500 g of carbohydrate and your liver about 100 g, enough for about 60 to 90 minutes of hard work, per Precision Fuel & Hydration (PF&H).

• PF&H: at least 8 g of carbs per kg of body weight in the 24 hours before, which “could be beneficial - especially if you expect to race for over two hours.”
• FuelHub’s Edward Mather: about 6 g/kg over the two days before, from easy foods like pasta, rice and potatoes, without overloading the night before.

Both agree: stick to familiar, low-fibre, low-fat foods to keep your gut calm.

Race morning: a simple timeline

When	What	Examples
2 to 4 hours before	High-carb, low-fibre meal	Toast, rice, porridge, overnight oats
1 to 2 hours before	Carb snack	Energy bar, rice, chews
30 minutes before	Small carb top-up, optional caffeine	Gel, banana, chews

PF&H uses the 2 to 3 hour window for the meal; Mather suggests 3 to 4 hours. Both say practise it in training so race day holds no surprises.

During the race: do you need a gel?

It depends on how long you’ll be out there:

Expected finish	Carbs during the race
Under about 60–75 min	Stored carbs should cover you; one gel is optional
75 min to 2 hours+	30 to 60 g per hour from gels, chews or sports drink

Most racers finish well over an hour (see what is a good HYROX time), so a gel or two is worth planning. PF&H suggests taking them at easier moments, like a Roxzone walk, to avoid stomach trouble.

The rules on carrying fuel

From the 2026/27 rulebook, as covered in our race-day bag checklist:

• Carry it from the start. “Any racers desiring nutrition must carry it on their person from the start of the race.”
• No hand-ups. Food or drink from anyone but the aid stations is a 2-minute penalty.
• Don’t litter. Dropping a cup or wrapper on course is also 2 minutes.

A hydration pack is on the permitted list; anything you carry stays with you all race.

Caffeine: the legal performance boost

PF&H says 3 to 6 mg of caffeine per kg of body weight has been shown to improve performance by lowering perceived effort and delaying fatigue.

Body weight	3 mg/kg	6 mg/kg
60 kg (132 lb)	180 mg	360 mg
75 kg (165 lb)	225 mg	450 mg
90 kg (198 lb)	270 mg	540 mg

Conversions are ours. Take it in the last 30 minutes as a caffeine gel, or as coffee about an hour before, per PF&H. Mather adds: if you haven’t practised with gels, stick to coffee. Start at the low end; more isn’t always better.

Hydration and electrolytes

• Pre-load: PF&H suggests a strong electrolyte drink with about 500 ml of water the night before and again 90 minutes before.
• During: sip at the Roxzone water stations, and for 75+ minute races PF&H suggests carrying a 500 ml soft flask of electrolytes.
• After: replace fluid with electrolytes, not just water.

Our best electrolytes for HYROX guide compares sodium content across brands.

After the finish line

PF&H suggests a meal with about 60 to 80 g of carbs and 20 to 30 g of protein soon after you finish, and to keep prioritising carbs for the next 24 hours. Mather recommends about 2 g of protein per kg per day while training for HYROX.

What to pack

Check price on Amazon: Maurten Gel 100 CAF 100 (caffeine gel) · Energy gels · LMNT electrolytes · 500 ml soft flask

The golden rule

Nothing new on race day. Test your meal, gel, caffeine dose and drink in at least one hard training session. Then put it all in your bag with our race-day checklist, and for supplements outside race day, see our supplements guide.