Can you run marathons on a ketogenic or carnivore diet?

Good news! You can!! If you’re already following a low-carb, keto, or carnivore diet, there’s no need to overhaul your nutrition and load up on carbs just because you’re training for a race. While it’s true that glucose provides a quick burst of energy and is a popular strategy among elite endurance athletes, it’s important to remember that what works for them doesn’t necessarily align with the needs of recreational runners or those prioritising health and longevity. In fact, elite athletic performance often comes at a cost to long-term health. For everyday runners or those aiming for sustainable performance, a ketogenic or carnivore diet can fuel your runs effectively, support faster recovery, and align with broader goals like anti-aging and overall well-being. Let's find out why sticking with your low-carb approach might be the smarter path forward.

Do you need carb loading?

Carbohydrate loading is popular amongst marathoners and ultra-runners aiming to maximise glycogen stores for long races. However, recreational runners, even those participating in marathons and ultras, often don’t need to fuel this way. High carbohydrate intake can often come at the cost of essential nutrients like protein and fat, leading to unintended consequences such as:

Poor Recovery

Focusing too heavily on carbohydrates often means reducing protein intake, which is essential for muscle repair and recovery. Without adequate protein—approximately 2-3g per kilogram of body weight daily—muscles may remain undernourished after training and racing, leading to prolonged soreness, increased inflammation, and slower recovery. Studies consistently show that balanced macronutrient intake, particularly post-exercise protein, significantly enhances muscle repair and reduces delayed onset muscle soreness (DOMS).

Hormonal Imbalance

A diet prioritising carbohydrates while neglecting dietary fat can disrupt hormonal balance, which is crucial for energy, recovery, and overall well-being. Essential fatty acids are needed for the production of hormones like cortisol, testosterone, and estrogen. When fat intake is insufficient, it can result in hormonal disruptions such as irregular menstrual cycles in women or reduced testosterone levels in men, ultimately impairing recovery, muscle growth, and long-term bone health.

Energy Swings

High-carb diets, especially those relying on refined carbohydrates, can cause significant fluctuations in blood sugar levels. These rapid spikes and crashes can leave runners feeling fatigued, irritable, and struggling to maintain consistent energy throughout their training or races. By focusing on a more balanced diet that includes complex carbohydrates, protein, and fat, runners can stabilise blood sugar levels, ensuring sustained energy and better overall performance.

Inflammation

Excessive carbohydrate intake, particularly from sugary or refined sources, can promote systemic inflammation, which is detrimental to recovery and injury prevention. Chronic inflammation not only delays muscle repair but also increases the risk of overuse injuries like tendinitis or plantar fasciitis. Instead, an anti-inflammatory diet rich in omega-3 fats and antioxidants supports faster recovery and reduces the risk of injury, allowing runners to train and race more effectively.

Benefits of Ketogenic and Carnivore Diets for Runners

A ketogenic diet (low carb, moderate protein, high fat) and a carnivore diet (animal-based, typically ketogenic) rely on fat as the primary fuel source. Learn what to eat on the carnivore diet in our previous blog article. Here are some science-backed benefits for runners:

Fat Adaptation

By becoming fat-adapted, your body can efficiently burn fat for fuel, providing a steady energy source. This is particularly advantageous for endurance activities.

Improved Recovery

High-quality protein from animal sources supports muscle repair and growth, helping you recover faster between runs.

Reduced Inflammation

Both diets are associated with lower inflammation markers, which may reduce injury risk and speed up recovery.

Steady Energy Levels

Without the highs and lows of blood sugar fluctuations, you’ll experience more consistent energy throughout your runs.

How to Perform Well on a Ketogenic or Carnivore Diet

Adapting to these diets as a runner requires some planning. Here’s how you can optimise performance:

Prioritise Electrolytes

 

Low-carb diets can increase sodium and potassium losses. Supplement with natural electrolytes to avoid fatigue and cramps during training and races. Even just adding a little bit of salt to your water bottle or food will help.

Increase Fat Intake

Make fats your primary energy source. Focus on high-quality sources like grass-fed beef tallow, butter, and fatty cuts of meat.

Include Adequate Protein

Aim for about 1.6-2.2 grams of protein per kilogram of body weight daily to support muscle repair and recovery. Increase it to 3g when in negative energy balance, racing, or recovering from illness/injury.

Be Patient

It can take 4-6 weeks for your body to become fully fat-adapted. During this time, performance and energy levels might dip temporarily.

Experiment with Timing

Some runners perform better with small pre-run meals, while others prefer running fasted. Test what works best for you.

Sample Nutrition Plan for Training and Racing

Training Days

Pre-Run (Optional): A Chief Collagen Bar for a quick and clean source of protein and fat and to increase tendon strength. You can also crumble the collagen bar into a full cream yoghurt or cottage cheese. If you are a carnivore, mix the Chief Unflavoured Collagen powder into yoghurt or cottage cheese to feed your tendons.

Post-Run Recovery: A meal of grass-fed and finished beef, paired with Chief Collagen Powder, added to bone broth for joint and muscle recovery.

Snacks:Chief Beef Bars or Carnivore Biltong

Supplements:Chief Liver Capsules to support overall energy and nutrient levels.

Hydration: Water with added electrolytes or a pinch of Himalayan salt.

Race Day

Pre-Race Meal: Stick to what you are used to and eat your regular pre-run meal.

During the Race: Consider Chief Beef Bars or Collagen Bars as an easily digestible fuel source for long races. If you are a carnivore, Chief Carnivore Biltong is your best pick.

Post-Race Recovery: A hearty meal with fatty meat and collagen-rich bone broth, supplemented with Chief Collagen Powder to aid recovery. If you find it too hard to eat straight after running, make a smoothie using frozen bone broth cubes, kefir and Chief Chocolate Collagen Protein powder. A delicious gut-healing hack to soothe you on the inside. Did you know that ultra-running often causes gut irritation, microbiome imbalance and even slight intestinal bleeding?

Addressing Common Concerns

Performance Drops

Some runners worry about reduced performance on a low-carb diet. While there might be a temporary dip during adaptation, many runners report equal or improved performance once fat-adapted.

Glycogen Replenishment

While ketogenic and carnivore diets limit carbs, they don’t deplete glycogen entirely. Protein can be converted to glucose via gluconeogenesis, and fat-adapted athletes utilise glycogen more efficiently.

Micronutrient Intake

Eating a variety of animal-based foods, including organ meats like liver, provides a rich source of vitamins and minerals. Chief Liver Capsules are a convenient way to ensure you meet your micronutrient needs.

Running performance doesn’t have to rely on carbohydrate loading, especially for recreational athletes. By focusing on fat and protein as primary energy sources, you can achieve steady energy, faster recovery, and improved overall health. Whether you’re following a ketogenic or carnivore diet, products like Chief Beef Bars, Collagen Bars, Collagen Powders, and Liver Capsules can support your running goals while keeping your diet clean and nutrient-dense.

References

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