Low carb diet is riding the wave around the world, also in endurance sports. Is it time for triathletes to go low carb?

The short answer is; No, at least not yet.

If you want a longer answer you can keep reading on.

First of all, nutrition is utterly complex. We are nowhere near a full understanding of how different food affects us. Especially in combination with other foods, looking at individual differences and at different stages like training, sleeping etc.

When we train we use energy made up of both carbs and fat. This varies with intensity, physical training and your diet. It also varies with the availability of carbs in your body. The main purpose for a low carb diet, from an endurance perspective, is to increase the body’s ability to utilize fat as energy. That again will make your carb storage hold longer which ultimately can make you hold a higher intensity for longer and finish faster.

Triathlon Taran did a low carb diet leading up to his first long-distance triathlon. That obviously worked for him, but did it work better than a carbs rich diet would? Note also that he did it under the guidance of Dan Plews, one of the world-leading expert on low carbs diets on performance. Taran also has a few interviews with athletes on a low carbs diet where they share their experience.

The reason for using diet to increase fat utilization is indeed valid. Some research studies are very promising. Why do I say that triathletes should not go low carb yet?

1. Decreased carb utilization – Going low carb definitely increase the fat utilization, especially for non-pro endurance athletes (pro endurance athletes often have a very high-fat utilization due to many years of high volume training). The downside is that it may decrease the body’s ability to utilize carbs. That can lead to decreased high-end performance.
2. Decreased ability to perform high-intensity training – Even with the very best fat burning engine available it will never match a carbs fueled engine when it comes ot maximum output. For that reason, it is very difficult/impossible to reach the highest intensities on low carb diets, except short duration. That will leave out training adaption potential.
3. Few world-class endurance athletes are going low carb – While that is not evidence for anything, it is evidence for world-class performances are mostly done on carb-rich diets. It also says that the potential performance gain in low carbs diets are relatively low even at perfect execution.
4. Making it work in real-life can be difficult – Of course, you can have whatever diet you want. Eating, however, is deeply ingrained in our social culture. Few Western cultures are all in on low carbs, especially when celebrating, which we tend to do a lot. For some that may not be a problem. For me, it would be an issue, because I feel I have enough special need from my environment as it is (like fitting in the training).
5. The risk of fuck-ups are high – This is the most important reason, in my opinion, for not going low carb. The potential for performance gain is there in some form, but the risk of fuck-ups are at least ten times higher. Underfueling, poor performance in training, poor recovery, poor sleep, too rapid weight loss (or weight gain) are some. If you are doing it, it should be under the guidance from a professional, a real professional, not people like myself 😉

I define me as an early adopter and keen to try out new things that might improve performance. Still, I see no reason to go as a front trooper in the low carb battle. Let others try, fail and hopefully succeed after a while. If the results are good (more than a handful), then it might be a time to try it out.

While I see that debates on diets often become extremely polarized, I try to not go into one camp or the other. My mind is open and my opinion will change. Remember that while reading low carbs success stories that it probably shows a distorted picture of reality. If someone tried low carbs and it worked great they are happy to share their good experience. If someone tried it and it did not work, they just move on to find the solution that works.

A healthy diet is something that often is overlooked in these debates. There are healthy and unhealthy variants of high carbs, low carb, vegan, carnivore, etc. My short diet advice is to integrate healthy diet habits and focus on eating enough to support your training load. If that is set, then you have a big room to play with in regards to variant diets.