How to Fuel Ultra Races on a Low Carb Diet: An Athlete’s Complete Guide

A staggering 35.6% of ultra runners drop out of 161-km races due to GI issues, with nausea being the primary culprit among 90.5% of affected athletes [41].

Sports nutrition textbooks preach the same gospel: consume 60-90g of carbs per hour during ultramarathons [41]. Yet some athletes are flipping this advice completely upside down. They’re ditching the endless stream of gels and sports drinks.

Instead of carb-loading, these runners restrict carbohydrate intake to just 5-10% of daily calories—roughly 25-35g per day—while cranking fat consumption up to 75% of total calories [41]. The results sound impossible: ultra runners completing 31-mile distances with nothing more than breakfast, a handful of nuts, and a few pickles [41].

Here’s what makes this approach intriguing. Fat-adapted athletes become “virtually bonk proof” because they can tap into nearly unlimited energy reserves. Most people carry at least 40,000 calories worth of body fat [41]. That’s enough fuel to power you through multiple ultra races without ever hitting the wall.

The trade-offs are real, though. Many athletes discover their aerobic capacity drops, making high-intensity efforts feel like running through quicksand [2]. Your body essentially loses its metabolic “top gear” for those moments when you need to surge up a steep climb or push through a technical section.

Research suggests this paradox might actually work for ultra-endurance events. Studies show low-carbohydrate, high-fat diets can enhance performance by supporting dramatically higher fat oxidation rates [41]. Elite athletes and exercise physiologists continue investigating whether this metabolic shift provides genuine advantages for ultra-distance competitions.

This guide reveals exactly how to fuel your ultra races using a low carb approach—from the adaptation process that transforms your metabolism to race-day nutrition strategies that keep you moving when conventional fueling fails.

Understanding Low Carb Diets for Endurance Athletes

Sports nutrition textbooks teach one approach to fueling endurance events. Low carb diets for athletes throw that playbook out the window, fundamentally rewiring how your body generates and sustains energy during long-distance efforts.

What is a low carb high fat diet for athletes?

A low carb high fat diet (LCHF) for athletes restricts carbohydrate intake to less than 25% of total daily calories, with fat comprising more than 50% of energy intake [42]. The ketogenic version takes this further—limiting carbohydrates to under 50g per day (about 5-10% of total calories), moderate protein (15-20% of energy), and significantly higher fat intake (75-80% of calories) [41].

Think about the math here. Standard athletic diets recommend 6-10g of carbohydrates per kilogram of body weight daily. A 70kg runner training 3 hours daily would typically consume up to 700g of carbohydrates on a conventional diet—approximately 20 times more than recommended for ketosis [8].

The ketogenic approach triggers a metabolic overhaul. Your liver starts oxidizing high concentrations of non-esterified fatty acids into ketone bodies: 3-hydroxybutyrate, acetoacetate, and acetone [41]. This state of nutritional ketosis produces blood ketone concentrations around 7-8 mM while maintaining normal blood pH of 7.4 [41].

How ketosis supports long-distance performance

Here’s where the science gets interesting for endurance athletes. Ketosis unlocks access to your body’s most abundant energy warehouse.

Your typical carbohydrate stores hold approximately 1680 calories total from muscle glycogen, liver glycogen, and blood glucose [41]. That’s enough fuel for maybe 2-3 hours of moderate exercise before you start bonking. Fat stores? That’s a different story entirely.

Research reveals dramatic improvements in fat oxidation among adapted athletes. Studies comparing long-term LCHF athletes to high-carb athletes found peak fat oxidation was 2.3 times higher in the LCHF group (1.54 g/min versus 0.67 g/min) [41]. Even more impressive—this peak fat utilization occurred at a higher percentage of VO2max (70.3% versus 54.9%) [41].

Fat-adapted ultra-endurance athletes can achieve fat oxidation rates up to 1.9g/min [41], shattering the 1.0g/min previously considered the physiological ceiling [41]. This metabolic efficiency means your energy levels stay remarkably steady without the constant need for external fuel during extended activities.

Is a low carb diet good for athletes?

The honest answer? It depends entirely on what you’re trying to accomplish and how your body responds.

Elite ultra-endurance athletes following LCHF diets show extraordinary fat oxidation capabilities, with mean fat utilization during submaximal exercise 59% higher than high-carb athletes [41]. This translates to fat providing 88% versus 56% of energy during prolonged activity [41].

But performance gains come with real costs. Research consistently shows that LCHF diets reduce your muscles’ ability to use carbohydrates efficiently [41]. You’re essentially trading your metabolic sprint speed for marathon endurance. One study demonstrated that despite increased fat oxidation, exercise economy declined by 5-8% at race-relevant speeds [41].

The approach works best for:

• Ultra-endurance athletes competing at intensities below 65% VO2max for extended periods [42]
• Athletes experiencing digestive issues with conventional fueling [8]
• Those seeking improved recovery and reduced inflammation [41]

Elite race walkers provide a cautionary example. Despite developing increased fat oxidation capacity, their performance didn’t improve (-1.6%) and oxygen cost actually increased [41].

Timing matters significantly. Most studies showing meaningful benefits examined athletes following LCHF diets for extended periods—ranging from 9 to 36 months [41]. Jump into this approach expecting immediate results, and you’ll likely experience temporary performance decline as your body learns this new fuel system.

Adapting to a Low Carb Fueling Strategy

Making the switch to fat-fueled racing isn’t like flipping a switch. Your body needs time to rewire its entire energy system, and frankly, the transition can feel brutal at first.

What is fat adaptation and how long does it take?

Fat adaptation represents a fundamental shift in how your body produces energy. Your metabolism transitions from primarily burning carbohydrates to efficiently utilizing fat as its main fuel source. The liver produces and releases ketone bodies into circulation—a state known as nutritional ketosis [41].

Your body initially functions like a car with a fouled spark plug as it adjusts to this new metabolic pathway. Over time, though, you become “keto-adapted,” meaning your systems learn to use ketone bodies as primary fuel [41]. This adaptation offers metabolic advantages as fat and ketone bodies provide energy in just three steps, compared to glucose oxidation which requires eleven steps [41].

The timeline varies, but here’s what most athletes experience:

• 2-4 days: Initial entry into ketosis [42]
• 4-12 weeks: Full fat adaptation development [41]
• 6-12 weeks: Optimal metabolic efficiency for endurance athletes [41]

Elite athletes sometimes adapt faster than weekend warriors. Studies show that even after just 5-6 days of dietary change, substantial increases (>200%) in exercise fat oxidation can occur, reaching mean rates of approximately 1.43g/min [41].

Common symptoms during the transition

Don’t worry – you’re not broken if you feel terrible during the first few weeks. Most athletes experience what’s commonly called the “keto flu” during the initial adaptation phase. These symptoms typically appear within the first few days and can last anywhere from several days to a few weeks [41].

You might encounter:

• Physical challenges: Fatigue, weakness, muscle cramps, dizziness, stomach discomfort [41]
• Mental effects: Irritability, difficulty concentrating, brain fog [41]
• Sleep disruptions: Difficulty sleeping and altered sleep patterns [41]
• Digestive issues: Constipation, diarrhea, nausea [41]

These reactions aren’t signs of failure. Your system is depleting stored glucose while desperately signaling for replacement, creating temporary discomfort [42]. Athletes often report a 20-30% reduction in pace during this period as energy systems recalibrate [41].

Think of it this way: your body is learning a completely new language, and like any language acquisition, fluency takes time.

Training adjustments during adaptation

High-intensity exercise relies heavily on carbohydrates, making those hard efforts feel impossibly difficult during the transition period. Smart training adjustments become essential.

For the first 2-3 weeks, dial everything back:

• Reduce intensity by 30-40% from your normal training pace [41]
• Shorten workout duration to 45-60 minutes maximum [41]
• Skip strenuous activities like intense biking, running, or weightlifting [42]
• Focus on gentle movement like walking, yoga, and leisurely cycling [42]

Around weeks 3-4, your body becomes more efficient at burning fat. Gradually reintroduce longer workouts, extending runs to 90-120 minutes while practicing fasted training to enhance fat metabolism [41].

Weeks 5-6 often bring a breakthrough moment. Mitochondria multiply and fat oxidation capacity increases significantly [41]. You’ll likely find yourself efficiently burning fat at 60-70% of your maximum heart rate, which perfectly aligns with ideal ultra-running intensity [41].

Maintain predominantly aerobic exercise throughout adaptation. Research shows your body burns substantially more fat at lower intensities [44]. Some successful low carb endurance athletes follow an 85/10/5 distribution—85% easy aerobic pace, 10% moderate effort, and only 5% high intensity [44].

Adaptation isn’t just about changing your diet—it’s about teaching your body to access different fuel systems effectively, ultimately expanding your metabolic flexibility for ultra-distance events.

Training on a Low Carb Diet

Training on low carb changes everything you thought you knew about fueling workouts. Your body’s new fat-burning machinery requires a completely different approach to prepare for, execute, and recover from training sessions.

How to fuel long runs without carbs

Forget everything about pre-run carb loading. Your fuel mix now looks dramatically different: 75% calories from fat, 20% from protein, and a mere 5% from carbohydrates [2]. Your body becomes remarkably efficient at accessing those abundant fat stores.

For runs extending beyond 60-90 minutes, these fat-based options become your new best friends:

• Medium-chain triglycerides (MCTs): These fats bypass normal digestion and provide quick energy during exercise [10]
• Electrolyte-rich foods: Avocados, olives, and nuts deliver both fats and essential minerals [2]
• Protein-fat combinations: Hard-boiled eggs, cheese, and nut butters offer sustained energy without carb crashes

Here’s what most athletes discover: GI distress virtually disappears. No more sugar-induced stomach rebellion from endless gels and sports drinks [2]. Your energy levels stay remarkably steady throughout long efforts—no more bonking when glycogen runs empty.

Balancing intensity and fat metabolism

Fat works beautifully for easy and moderate efforts. Below 40% VO₂max, fat dominates as your primary fuel source [11]. During moderate intensity work (40-65% VO₂max), fat still contributes roughly half your energy needs [11].

Push harder than this, and you’ll hit the metabolic ceiling fast. High-intensity training becomes genuinely challenging on low carb because fat requires more oxygen to burn than carbohydrates [2]. You’re essentially working at a higher percentage of VO₂max without the performance payoff.

Smart low carb athletes structure training around this reality:

1. Build massive aerobic base with high-volume, low-intensity work
2. Time strategic carbohydrate intake for specific high-intensity sessions
3. Gradually reintroduce intensity as fat adaptation deepens

Research shows carbohydrate-restricted training actually enhances cellular signaling and upregulates metabolic enzyme adaptations in skeletal muscle [12]. Your body becomes more efficient at using whatever fuel you give it.

Using fasted training strategically

Fasted training accelerates fat adaptation like nothing else. Train without eating for 8-12 hours, and your body has no choice but to burn stored fat for fuel.

Studies reveal fascinating adaptations: delayed glycogen restoration enhances glucose uptake proteins, specifically the GLUT-4 transporter [12]. Withhold carbs after exercise (while maintaining adequate total energy), and insulin sensitivity improves the next day [12].

Execute fasted training with these guidelines:

• Stick to low-intensity, Zone 1-2 efforts only [13]
• Start with 30-45 minutes and extend gradually as adaptation improves
• Expect higher perceived effort—this is normal during fasted sessions [3]
• Morning sessions after overnight fasting work best practically

Don’t go overboard, though. Reserve high-intensity efforts, strength training, and technical sessions for properly fueled states [3]. Female athletes need extra caution—energy restriction can trigger negative hormonal responses [3].

Master these training adaptations, and you’ll develop true metabolic flexibility—the ability to efficiently burn both fat and carbohydrates depending on what your body needs most.

Race Day Fueling on a Low Carb Diet

Race day strips away all the theory. Your months of fat adaptation training either work or they don’t. Unlike traditional carb-loading strategies, successful low carb racing demands a delicate balance between minimal carbohydrate intake and optimal fat utilization.

How much fat and carbs to consume during an ultra

Even the most dedicated fat-adapted athletes need some carbohydrates during ultra races. The question isn’t whether to consume carbs—it’s how much.

Research shows fat-adapted ultra-endurance athletes still benefit from 30-60g of carbohydrates per hour—significantly less than the 60-90g recommended for conventional athletes [14]. This strategic carbohydrate intake supports performance without disrupting ketosis.

Here’s the metabolic advantage you’ve earned through adaptation: while high-carb athletes derive approximately 56% of energy from fat during endurance events, fat-adapted competitors can achieve 88% fat utilization [1]. This efficiency means you rely far less on external fueling.

Real-world carbohydrate consumption varies among successful low carb ultra-endurance athletes:

• 31g/hour in ultra-marathon races [1]
• 42g/hour in multi-day desert events [1]
• 56g/hour in ultra-marathons lasting over 78 days [1]

Performance data reveals a clear pattern: faster finishers typically consume more total calories than non-finishers. Athletes consuming over 40g of carbohydrates hourly averaged 92.2 miles in a 24-hour race, while those consuming less than 40g covered only 74.7 miles [15].

Your protein intake should constitute approximately 19% of race-day calories [1]. This prevents muscle breakdown during extended efforts while supporting cognitive function when decision-making becomes critical.

Best keto-friendly race foods and snacks

Your race food selections must pass three tests: digestibility, portability, and macronutrient profile. Traditional sports nutrition fails on all counts for fat-adapted athletes.

Proven fat-based fuel sources include:

• Nut-based options: Macadamia nuts (highest fat content at 21g per ounce), nut butters in portable pouches [6]
• Protein sources: Hard-boiled eggs, cheese (especially string cheese and Babybel rounds), jerky (check for added sugars) [16]
• Savory items: Olives, avocados (double the potassium of bananas), cold roasted potatoes dipped in butter [17]
• Portable fats: MCT oil (acts similarly to carbohydrates for absorption but provides fat-based energy) [18]

Medium-chain triglycerides (MCTs) offer unique advantages for fat-adapted athletes. Unlike standard fats, MCTs bypass lengthy digestive processes, providing readily available energy similar to carbohydrates [18]. Exercise caution with dosing—excessive consumption may cause digestive distress.

Strategic carbohydrate timing remains beneficial even on a low carb approach. For races exceeding 12-24 hours, incorporating limited carbohydrates from sources like fruit can support performance without compromising fat adaptation [8].

Timing your intake for long events

Timing matters more than total quantity during ultra-distance events. “Front-loading” your nutrition—consuming more calories earlier in the event—capitalizes on your body’s superior absorption capacity during the race’s initial hours [17].

Your body processes nutrition more efficiently during daylight hours than overnight. Plan to consume more calories during daylight portions of 24+ hour events, being more patient with intake during overnight sections [17].

For multi-day events, consider adopting a fat-adapt strategy 5-10 days prior to racing. This approach includes consuming 60-70% fat and only 15-20% carbohydrates to further enhance fat metabolism [1].

Ultra-distance races demand flexibility in your fueling plan. Listen to your body’s cravings, particularly regarding salt intake. Rather than rigidly following electrolyte supplementation protocols, consuming salty foods based on taste preferences often provides more intuitive electrolyte balance [14].

Hydration should follow thirst cues rather than predetermined schedules. Drinking larger volumes every 20 minutes promotes better absorption than frequent small sips, though technical terrain may necessitate the latter approach [14].

Your race-day fueling strategy must balance theoretical ideals with practical execution. Test these guidelines extensively during training to develop a personalized approach that supports optimal performance throughout your ultra-distance events.

Hydration and Electrolyte Management

Have you ever felt great at mile 30 of an ultra, only to watch your energy crater completely by mile 40? Your fueling strategy might be perfect, but electrolyte imbalance can derail your race just as quickly. Low carb athletes face unique hydration challenges that conventional sports nutrition advice simply doesn’t address.

Why sodium and potassium matter more on keto

Your kidneys work differently when you’re fat-adapted. Lower insulin levels trigger increased sodium and electrolyte excretion [4]. Think of it this way: carbohydrates act like sponges, holding water in your system. Remove those sponges, and your body releases more water—along with precious minerals [19].

Conventional wisdom tells athletes to limit sodium intake. That advice becomes dangerous for low carb athletes who need 4-6 grams daily [20]. Athletes with high sweat rates or concentrated sweat face even greater risks of hyponatremia when sodium intake falls short [21].

Potassium works hand-in-hand with sodium for proper muscle function and energy metabolism. You should target 3.5-5 grams of potassium daily [20], yet a staggering 97% of Americans don’t meet this requirement [20]. Fat-adapted athletes often see potassium levels drop further without careful attention [5].

How to avoid dehydration and hyponatremia

Walking the tightrope between dehydration and hyponatremia requires understanding your body’s signals. Too little fluid leaves you cramping and dizzy. Too much dilutes your blood sodium to dangerous levels [21].

Watch for dehydration warning signs: thirst, fatigue, dark urine, dizziness, headaches, and muscle cramps [4]. Hyponatremia presents differently—nausea, lethargy, muscle cramps, headaches, and in severe cases, seizures or coma [21].

Your strategy should include:

• Accept 2-3% weight loss during long events as normal and healthy [22]
• Trust your thirst over rigid drinking schedules [22]
• Plan sodium supplementation for events exceeding 12 hours [22]
• Skip NSAIDs during races—they increase hyponatremia risk by affecting hormone regulation [22]

Electrolyte supplements vs. real food sources

Real food beats synthetic supplements every time when it comes to bioavailability [23]. Your body recognizes and utilizes natural sources more efficiently.

Smart keto-friendly electrolyte sources:

• Sodium: Salt your food liberally, sip bone broth, choose salted nuts and seeds [5]
• Potassium: Load up on avocados, leafy greens, and mushrooms [5]
• Magnesium: Reach for pumpkin seeds, nuts, and leafy vegetables [5]

Sometimes supplements make practical sense, especially during adaptation or heavy training blocks. Salt substitutes with potassium chloride can boost potassium without adding sodium [5]. Electrolyte powders offer convenience when you need precise mineral ratios [7].

The winning approach combines targeted supplementation with nutrient-dense whole foods, adjusted based on your individual sweat rate, training load, and environmental conditions.

Troubleshooting Common Issues

Even the most carefully planned fat-adapted race can throw you curveballs when you’re 50 miles deep into an ultra. Knowing how to troubleshoot these issues quickly can save your race and keep you moving toward the finish line.

Dealing with GI distress on a low carb diet

Low carb diets may reduce gastrointestinal problems for many athletes, but don’t assume you’re immune to gut issues [2]. Approximately 50-80% of ultra runners still battle some form of GI distress during races, with 65% reporting severe symptoms [24]. Remember that 35.6% of non-finishers in 161km ultras drop out due to GI problems, with nausea leading the charge (90.5% of cases) [9].

Your gut training becomes as important as your leg training. Practice your exact race nutrition strategy during long training runs—your digestive system needs to adapt just like your muscles do. If you’re dealing with recurring problems, consider trialing low-FODMAP foods during your next training block [24].

Here’s a strategy that works: separate carbohydrates, fluids and electrolytes (the “three key levers”) to maintain flexibility when your gut rebels [9]. Don’t overwhelm your system by cramming excessive calories at once [9]. Small, frequent intake beats large boluses every time.

What to do if you hit the wall

Despite your fat adaptation, energy deficits of nearly 10,000 kcal/day can occur during ultra events [24]. Even fat-adapted athletes aren’t completely wall-proof.

First, stay calm and diagnose the real problem—are you dealing with energy depletion, dehydration, or GI distress [9]? Each requires a different solution. Slow your pace immediately to give your body time to process whatever nutrition you’ve already consumed [9]. Keep moving if possible—stopping completely makes restarting feel like trying to push a boulder uphill [9].

For keto athletes, here’s something interesting: 90% of ultra runners show urinary ketones post-race [24]. If you’re experiencing glycogen depletion, strategic carbohydrate intake can help without completely disrupting your adaptation.

Signs your fueling plan needs adjustment

Watch for “sweet fatigue”—that moment when the thought of another gel makes you want to quit [24]. This phenomenon is real and happens to most ultra runners as races progress. Combat it with palate diversity: broth, cheese, nut butters, or anything savory [24].

Other red flags include persistent fatigue that doesn’t improve with fueling, brain fog that makes simple decisions feel impossible, or GI disturbances that won’t settle [25]. Don’t ignore these warning signs—they’re your body’s way of telling you something needs to change.

Extreme underfueling carries serious consequences: bone loss, stress fractures, and thyroid dysfunction [25]. A poorly formulated low carb diet can also trigger constipation, electrolyte imbalances, and vitamin deficiencies [26]. Regular assessment of your fueling strategy isn’t optional—it’s essential for both race success and long-term health.

Your fueling plan should evolve as you learn what works. Stay flexible, listen to your body, and don’t be afraid to adjust course when things aren’t working.

Wrapping Up Your Low Carb Ultra Journey

Fat-adaptation for ultra racing challenges everything you’ve learned about sports nutrition. This approach flips conventional fueling wisdom on its head, trading constant carbohydrate intake for metabolic flexibility that taps into your body’s vast energy reserves.

Don’t expect this transition to happen overnight. Your metabolism needs 4-12 weeks to fully adapt, and those early training sessions will feel sluggish as your body learns its new fuel system. The temporary performance dip is normal—your energy systems are essentially rewiring themselves to burn fat efficiently.

Race day execution becomes an entirely different game. Instead of cramming down sugary gels every 30 minutes, you’ll fuel strategically with 30-60g of carbs per hour while relying primarily on fat stores. Many athletes discover this approach eliminates the GI disasters that plague traditional ultra fueling.

Electrolyte management demands extra attention on this protocol. Your kidneys will dump more sodium and potassium, requiring careful monitoring and replacement. The difference between finishing strong and struggling often comes down to getting these minerals right.

Sometimes things go sideways during your event despite perfect preparation. Learn to troubleshoot on the fly—recognize when your fueling plan needs adjustment, know how to address sudden GI distress, and understand when strategic carb intake might save your race.

This metabolic approach works brilliantly for some athletes while leaving others feeling flat and sluggish. Your individual response depends on genetics, training background, race distance, and how well your digestive system handles the transition.

Test this strategy thoroughly before committing to it for your goal race. Practice the full protocol during long training runs, experiment with different fat-based fuels, and learn how your body responds to fasted training sessions.

Ultra racing success ultimately comes down to finding your personal formula. Fat adaptation offers legitimate advantages—stable energy, reduced GI distress, and access to nearly unlimited fuel stores—but it requires patience and systematic implementation.

The athletes who succeed with this approach share one common trait: they commit fully to the process and give their bodies time to adapt. Are you ready to challenge conventional nutrition wisdom and discover what fat-fueled performance feels like?

Key Takeaways

Master these essential strategies to successfully fuel ultra races while following a low-carb approach and unlock your body’s fat-burning potential.

• Fat adaptation takes 4-12 weeks – Allow sufficient time for your body to efficiently burn fat as primary fuel before attempting ultra races on low-carb nutrition.

• Consume 30-60g carbs per hour during races – Even fat-adapted athletes benefit from strategic carbohydrate intake, significantly less than traditional 60-90g recommendations.

• Prioritize electrolyte management – Low-carb athletes need 4-6g sodium daily due to increased kidney excretion, making proper mineral balance critical for performance.

• Train your gut with fat-based fuels – Practice race nutrition using nuts, MCT oil, cheese, and avocados during long training sessions to prevent GI distress.

• Expect temporary performance decline – Reduce training intensity by 30-40% during the first 2-3 weeks of adaptation as your metabolism shifts to fat utilization.

The low-carb approach offers access to nearly unlimited energy stores (40,000+ calories from body fat) while potentially reducing the GI issues that cause 35.6% of ultra runners to DNF. However, success requires patience during adaptation, strategic race-day fueling, and meticulous electrolyte management to maintain performance throughout your ultra-distance events. Embracing the benefits of low carb training can lead to improved fat oxidation and enhanced endurance over time. Athletes often report feeling more stable energy levels and reduced hunger, allowing for more focused training sessions. Ultimately, the strategic implementation of a low-carb regimen can be a game changer for those looking to optimize their performance in endurance sports.

FAQs

Q1. Can you successfully run ultramarathons on a low-carb diet? Yes, it’s possible to run ultramarathons on a low-carb diet, but it requires careful planning and adaptation. Some athletes, like Jeff Browning, have had success with a low-carb approach for training while strategically using carbs during races. However, it’s important to note that individual responses vary, and this approach may not work for everyone.

Q2. How long does it take to adapt to a low-carb fueling strategy for endurance running? The adaptation period to a low-carb diet for endurance running typically takes 4-12 weeks. During this time, your body learns to efficiently use fat as its primary fuel source. Athletes may experience reduced performance initially, but many report improved fat oxidation and steady energy levels once fully adapted.

Q3. What are some low-carb fueling options for ultra races? Low-carb fueling options for ultra races include nut butters, MCT oil, avocados, hard-boiled eggs, and cheese. Some athletes also use specially formulated low-carb products like UCAN Superstarch. However, it’s crucial to test these options during training to ensure they work for you during a race.

Q4. How does a low-carb diet affect hydration and electrolyte balance in ultrarunners? A low-carb diet can significantly impact hydration and electrolyte balance in ultrarunners. Due to lower insulin levels, the body tends to excrete more sodium and water. As a result, low-carb athletes often need to increase their sodium intake to 4-6 grams daily and pay extra attention to potassium and magnesium levels to maintain proper electrolyte balance.

Q5. Are there any potential drawbacks to following a low-carb diet for ultra running? While some athletes thrive on a low-carb diet, there are potential drawbacks. These may include reduced high-intensity performance, initial adaptation difficulties, and the need for careful nutrient planning. Some studies also suggest that long-term very low-carb diets could potentially impact liver health in endurance athletes. It’s essential to monitor your body’s response and consult with a sports nutritionist if considering this approach.

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[43] – https://www.orthocarolina.com/blog/are-you-underfueling
[44] – https://www.hprc-online.org/nutrition/performance-nutrition/ketogenic-diet-and-performance-basics