The concept of a low-carbohydrate high-fat (LCHF) diet, which has been praised by Arctic adventurers and extreme explorers for its benefits, gained wider popularity in the early 2000s due to the emergence of fad diets like the Atkins and paleo diets.
Instead of becoming insignificant, the interest in the LCHF diet and its related theory has persisted and eventually extended to endurance sports.
Is a high-fat diet the future of distance running
In the past, it has been commonly advised by exercise physiologists and nutritionists to include a relatively large quantity of carbohydrates in one’s diet. The rationale behind this recommendation is quite straightforward: individuals engaged in endurance running tend to utilize a significant amount of carbs during their training sessions, and studies have shown that consuming a high-carb meal prior to a long-distance running competition, such as a marathon, can have advantageous effects on performance.
However, a different narrative has recently come to light.
Physiologists Timothy Noakes, Jeff Volek, and Stephen Phinney contend in a 2014 editorial that high-carbohydrate diets pose health risks, and assert that athletes can eventually adjust to diets abundant in fat and deficient in carbohydrates.
This is the agreement:
There are two alleged advantages: firstly, athletes following a high fat diet may sidestep any health complications that could be linked to a high carb diet.
Additionally, the authors suggest that athletes following a high fat diet can experience alterations in cellular metabolism that enable them to effectively burn fat at an accelerated pace. Consequently, they posit that this could provide a significant advantage in endurance events, as a “fat-adapted athlete” would be capable of participating in multi-hour training sessions or competitions without the necessity of consuming external sources of nourishment.
The appeal of LCHF for ultra runners
However, the ultra running community started paying attention. In a sport that already prioritizes fat-burning ability due to its low intensity, a decrease in sprinting strength is not a major worry. Additionally, one of the most difficult aspects of ultra running is the struggle to replenish energy, as anyone who has attempted to consume their tenth flapjack after spending twelve hours in the mountains can attest to.
Depending on external sources of carbohydrates is mentally exhausting and can be a gastrointestinal disaster for those with little experience. Opting to depend on the continuously burning flame of your abundant internal fat stores is not only physiologically efficient but also brings psychological relief. It didn’t take long for elite ultra runners to grasp this concept.
Both Timothy Olson, formerly holding the course record at Western States, and Zach Bitter, who achieved a U.S. track 100-mile record in 2015, have adopted LCHF diets.
Jeff Volek, a dietitian and researcher who co-authored an editorial with Noakes questioning the significance of carbohydrates for athletes, asserts that the advantages of a low carb diet become more evident beyond the marathon, as carbohydrates become depleted at that stage.
In recent times, a new method of managing carbohydrate and fat consumption has emerged, wherein athletes restrict their overall carbohydrate intake while increasing it prior to and during extended runs and races.
Moreover, a method known as the fasted workout has gained popularity, which allows for an increase in the utilization of fat reserves as energy during exercise without making changes to one’s diet.
When specific workouts are chosen to be done in a carbohydrate-depleted state (for instance, having a dinner without carbohydrates and then doing a morning run before eating breakfast), the body is compelled to utilize fat as energy, protecting the crucial glycogen reserves, and encouraging the body to become accustomed to using stored fat as fuel as a result.
Nonetheless, the argument continues to divide opinions. Despite undeniable success experienced by certain athletes who follow the LCHF diet, various studies have revealed a general decline in exercise performance and, in certain instances, an adaptation period so unpleasant that it could be deemed detrimental to health.
Our understanding of how different metabolic fuels impact endurance performance is still incomplete, and further research is needed to gain a conclusive understanding. The influence of individual factors and the specific sport also play a role in determining the ultimate effects.
Considering these conditions, the LCHF undeniably offers ultra runners an enticing chance to forego their reliance on bananas and sports gels and instead develop a more effective, fat-powered, long-distance mechanism.
Research behind the high-fat claims
Are these claims truly valid or just impressive-sounding? Noakes, Volek, and Phinney themselves acknowledge the insufficient nature of current research.
Even later studies, such as a 2012 paper conducted by researchers from the University of Rome, found that a low carbohydrate diet did not have an impact on the 30-minute time-trial performance. However, these studies also suffer from the limitation of small sample sizes, with only six masters athletes included in this particular study.
Things become even more unfavorable.
The effects of a low carb diet in ultramarathoners were also examined by researchers at the University of Connecticut and The Ohio State University.
The researchers proposed that a low carb diet could potentially reduce the typical increase in inflammation experienced after engaging in long distance running, based on previous studies that demonstrated the ability of such diets to lower inflammatory indicators in obese and sedentary individuals.
A substantial number of twenty male ultramarathoners were chosen, with half of them following traditional high carbohydrate diets as their regular practice, while the other half adhered to a low-carb / high fat diet (consisting of 11% calories from carbs, 71% from fat, and 19% from protein).
Blood samples were collected and examined for inflammation markers after a three-hour treadmill run. Although the run did cause the anticipated increase in inflammatory markers in the blood, there was no significant distinction in their levels between the high fat diet and high carb diet groups.
Why are we still considering a high-fat diet good for runners
However, there is abundant evidence supporting Noakes, Volek, and Phinney’s assertion that high fat diets indeed modify cellular metabolism. Asker Jeukendrup’s 2003 review article presents multiple studies that illustrate how the body reacts to a high fat, low carb diet by enhancing its capacity to utilize and oxidize fat as an energy source during physical activity.
How can we define the term “fast”?
According to Jeukendrup, when you reach over 75% of your VO2 max, the amount of fat burned by your body decreases significantly. As a point of comparison, the pace maintained during a marathon race falls within the range of 75-85% of VO2 max. Consequently, while adopting a high fat diet may delay the necessity for refueling during extensive training runs and ultramarathon races, it will not prevent the occurrence of “hitting the wall” in a marathon race.
Noakes, Volek, and Phinney could argue that the health risks of high carb diets in athletes are also uncertain, as Jeukendrup mentions that the long-term health consequences of a high-fat diet in athletes remain unknown.
What’s the bottom line?
We will need to exercise patience as usual until the comprehensive and systematic research is conducted to ultimately settle these arguments.
Up until that point, it seems that the only individuals who seem to gain advantages from a diet high in fat but low in carbohydrates are ultramarathoners and Ironman triathletes. Their extensive training sessions and competitions are of sufficient duration to provide a clear competitive edge by burning more fat and fewer carbohydrates during moderate exercise intensities.
Best high-fat foods for ultra-marathoners
We will reveal the top foods you can incorporate into your diet for those endurance exercises that require running longer distances at a moderate intensity, enabling your body to utilize fat as fuel.
Adding these 20 foods to your diet won’t have negative consequences, but it doesn’t imply that you can indulge in fried chicken and expect to burn it all off during your next endurance event. It’s important to note that not all fats are equivalent.
- Almonds
- Walnuts
- Pecans
- Macadamia Nuts
- Cashews
- Pistachios
- Avocados
- Black Olives
- Dark Chocolate
- Chia Seeds
- Flax Seeds
- Pumpkin Seeds
- Sunflower Seeds
- Olive Oil
- Coconut Oil
- Butter
- Chickpeas
- Whole Eggs
- Full Fat Yogurt
- Parmesan Cheese
- Cream Cheese
- Beef (Grass-Fed if possible)
- Salmon
- Trout
- Mackerel
- Sardines
- Herring
Before making any significant changes to your diet, it is important to consult with a doctor. However, if you decide to reduce your carbohydrate intake and opt for a high-fat diet instead, we would appreciate if you shared your experience in the comments. Your feedback could be beneficial for other runners who are looking to improve their running and overall well-being.
