My keto experience

Photo by David B Townsend on Unsplash

In the middle of my Ironman training, I was on a keto “diet” for a couple of weeks. The goal was NOT to lose weight(I feel like I have to point that out because of the “diet” word). The goal was to make the body get used to using fats as fuel. During an Ironman (10+ hours), burning roughly 500 kcal every hour — there’s no way that I can get that many calories in me during that time. So the body needs to use stored fats.

Previously I’ve done fasted bike rides and similar things, but I wanted to take it one step further. I also listened to parts of the Joe Rogan podcast episode with Mark Sisson where they talked about things related to this. They talked about other benefits of doing something similar, not for endurance athletes specifically. I didn’t do any more research, so if you’re going to do something similar — please do your research or reach out to a professional.

What I learned

What to eat

The most difficult thing was to figure out what to eat. I love my oatmeal in the morning, as well as my rice/pasta/potato with my meat for lunch and dinner. After a couple of days of trying different things, I found something that worked for me:
– Breakfast: boiled or scrambled eggs.
– Lunch & dinner: some kind of meat (usually red meat higher in fat) or salmon with a lot of vegetables.
– Evening meal: fruits&greens protein shake.
* and snacking on nuts throughout the day.

It was also difficult to figure out what to use for nutrition during workouts. Usually, I consume gels, carb + electrolyte -drinks, energy bars, or bananas — but now I “couldn’t” consume any of them. So I just consumed nuts.

So my biggest obstacle was the lack of knowledge. I’m sure there would be a lot of better options out there. But this worked for the short time I did it. I would absolutely not be able to stay on this “diet” for a much longer period.

Body getting acclaimed to the new diet

*Sensitive readers, skip this part*

After a couple of days, my stool was getting dark, almost black, and really sticky. I was pretty sure this was because of the “diet”, but still Googled it and found a nice video describing what’s happening inside the body — how it’s breaking things down differently. In the video, they said that it would go back to normal within a week, as it did.

During these two weeks, I didn’t need to use the bathroom as much as I usually do.

Not as hungry

During this period, I didn’t get as hungry as I normally do. I don’t want to go into the facts/research of why this happens, if you’re interested you can Google it, but it makes sense. It was nice to really be in control, and only eat when I “needed to” — truly using the food as fuel.

Everyone can probably relate to the carb-heavy lunches that make you crash mid-day. This didn’t happen, I felt good the whole day.

Because of this experience, I’m going to change my diet slightly — consuming fewer carbs and more vegetables and fats.


Even if this wouldn’t have any impact on my Ironman training/racing, I still think it was a success. I’m a big advocate of trying new things. I’ve probably been eating carbs every day my whole life, so shocking the body by leaving them out is probably a good thing — making the body figure it out and work in a different way (again, based on “what I’ve heard”, don’t take my word for it). As mentioned, based on how I was feeling, I will be making changes to my normal diet as well.



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Andreas Westerlund

Andreas Westerlund

Endurance athlete, digital nomad, nerd. Just a normal guy trying to figure out fitness, business, and life.