Should You Carb Load for HYROX?

November 24, 2025 •

4 min read

Most athletes are aware that maximizing muscle glycogen stores is key for long endurance events like a marathon, but HYROX is different. With a unique combination of strength and running, the question of whether you should carb load for HYROX requires a nuanced approach to nutrition.

Quick Summary

This guide breaks down if and how to carb load for a HYROX race, covering the scientific rationale, practical fueling strategies, and key nutritional differences from other endurance sports. Learn how to time your carbohydrate intake in the days leading up to the event for peak performance.

Key Points

Strategic, not massive: A targeted 48-72 hour carb load is more effective for HYROX than the extreme loading used for marathons.
Practice your fueling: Always test your race week and race day nutrition plan during training to prevent gastrointestinal issues.
Focus on low-fiber carbs: Opt for easily digestible carbohydrates like white rice, pasta, and bananas in the days leading up to the race to minimize stomach upset.
Don't forget hydration: Proper hydration with electrolytes is just as critical as carb intake for maintaining performance and preventing fatigue.
Intra-race gels are optional: For athletes finishing under 75-90 minutes, mid-race fueling may not be necessary, but it can be beneficial for longer race times.
Race morning matters: Your final carb-rich meal or snack should be timed 2-4 hours before your start to top off glycogen stores.

Understanding HYROX's Unique Energy Demands

Unlike a pure endurance event such as a marathon or a pure strength competition, HYROX is a 'hybrid' race that demands both sustained aerobic capacity and explosive power. Competitors complete eight 1km runs interspersed with eight functional workout stations. The total race duration typically falls between 60 and 180 minutes for most athletes, placing it in a nutritional gray area between short, high-intensity workouts and ultra-endurance events. This duration means that relying solely on your existing glycogen stores is a risk, but the intensity is high enough that overdoing your pre-race fueling can cause unwanted gastrointestinal distress.

Your body primarily uses stored carbohydrates, known as muscle glycogen, during high-intensity exercise. A successful HYROX performance hinges on preventing these stores from becoming depleted, which would lead to a significant drop in power output and an increase in perceived effort. This is where a targeted carb-loading strategy comes into play.

The Targeted Approach to Carb Loading for HYROX

Traditional carb loading often involves a depletion phase followed by massive carbohydrate intake. For HYROX, a more modified, less extreme approach is recommended to avoid unnecessary stress and bloating. Instead of a drastic diet change, the goal is to gradually increase your carbohydrate intake in the 48-72 hours leading up to the race. This helps 'super-compensate' or maximize your muscle and liver glycogen without causing discomfort. Experts recommend increasing your intake to around 5-10 grams of carbohydrate per kilogram of body weight per day in the final two days before your event. Simultaneously, it's wise to reduce your fiber and fat intake slightly to reduce the risk of gastrointestinal issues on race day.

Race Week Carb-Loading Timeline

7-4 days before: Maintain normal, consistent carbohydrate intake (approx. 5-7g/kg) while training volume decreases. This sets the foundation for your loading phase.
3-2 days before: Increase carb intake to around 8-10g/kg per day. Focus on low-fiber, complex carbs and reduce your training load significantly.
1 day before: Consume 8-10g/kg of carbs from easily digestible sources. Have a final moderate-sized, high-carb meal 3-4 hours before bedtime.
Race morning: Have a light, familiar, high-carb breakfast 2-4 hours before your start time. Top up with a small, fast-acting carb snack 60-90 minutes out.

Practical Carbs: What to Eat

Choosing the right foods is as important as the timing. Opt for easily digestible, carbohydrate-dense options that you have practiced with during training.

Good Choices for Carb Loading

Grains: White rice, pasta, oatmeal, low-fiber cereals, bagels.
Fruits: Bananas, applesauce, dates, fruit smoothies.
Snacks: Pretzels, rice cakes, low-fat energy bars.
Liquids: Sports drinks or fruit juices can add significant carbs without feeling overly full.

Comparison: HYROX Carb Loading vs. Marathon Carb Loading


Aspect	HYROX Carb Loading	Marathon Carb Loading
Timing	48-72 hours leading up to the event.	3-6 days before, potentially involving a depletion phase.
Intensity	A modified, more gentle approach is sufficient due to a shorter race duration and hybrid demands.	Traditional, high-volume loading is typical to prepare for sustained 100% aerobic effort.
Focus	Maximizing glycogen without causing GI distress from overeating or too much fiber.	Filling glycogen to the absolute maximum to prevent hitting 'the wall' in longer, slower efforts.
Intra-race fuel	Small, frequent intake of gels or sports drinks may be needed for races over 75-90 minutes.	More consistent and higher-volume intra-race fueling is standard.

Hydration and Electrolytes are Crucial

While carb loading fills your energy stores, proper hydration is non-negotiable for a strong HYROX performance. Dehydration can lead to a significant drop in power output and cognitive function, which is detrimental during a race that requires both physical and mental focus. Begin hydrating effectively in the days leading up to the race and consider supplementing with electrolytes, especially if you expect to sweat heavily. A strong electrolyte drink pre-race can help ensure you start fully hydrated.

Conclusion

So, should you carb load for HYROX? The answer is a clear yes, but with a strategic, tailored approach that differs from traditional endurance events. By focusing on a moderate increase of easily digestible carbohydrates in the 48-72 hours before your race and nailing your hydration, you can ensure your glycogen stores are topped up and ready for the unique hybrid demands of a HYROX. Don't fall into the trap of over-fueling or trying new foods on race day; practice your fueling strategy during your longer training sessions. Ultimately, smart nutrition combined with your dedicated training will pave the way to a peak performance. For more detailed nutrition strategies for hybrid athletes, visit the Precision Hydration blog..

Frequently Asked Questions

The primary energy source is stored carbohydrates, known as muscle glycogen, especially during the high-intensity running and strength station intervals.

HYROX requires a less extreme, more targeted carb-loading strategy over 48-72 hours due to its shorter duration and hybrid demands. Marathons require a longer, higher-volume loading period.

For your pre-race breakfast, focus on a high-carb, low-fiber, and low-fat meal eaten 2-4 hours before your start time. Examples include oatmeal with a banana or toast with honey.

For races longer than 75-90 minutes, consuming 30-60g of carbs per hour via gels or sports drinks can be beneficial. For shorter races, a small amount may be optional, but always prioritize hydration.

Hydration is extremely important. Losing just 2% of your body weight through sweat can impair performance. Proper fluid and electrolyte intake before and during the race helps prevent cramping and fatigue.

During the 48-72 hour loading phase, choose easily digestible, lower-fiber carbs like white rice, pasta, oats, and bananas to maximize glycogen stores without causing stomach upset.

In the final 48-72 hours, a carbohydrate intake of 5-10 grams per kilogram of body weight per day is recommended, with the higher end reserved for the heaviest training days or the day before the race.