It depends on who you ask! Chris Carmichael and Jim Rutberg recently published an article discussing this exact topic. As I expected, they do not believe a ketogenic diet will improve overall performance for endurance athletes. I expected this as the research and science supporting a ketogenic diet is still relatively new, and it would take a major paradigm shift for coaches like this who have been following a successful nutrition program with their athletes for a long, long time.
But I did find the comments at the end of the article very interesting. Several who commented did find their performance has improved on a ketogenic diet. Others saw improvement with a low carb diet and strategic carb cycling.
If you ask Stephen Phinney or Jeff Volek, I suspect they would tell you that a low carb or ketogenic diet absolutely improves performance based on research they have done with cyclists and other endurance athletes. As you’ll note in their research and something I completely believe in, they key is to be fat adapted. It took me several months to become fat adapted and to start reaping the benefits of a ketogenic diet when I was riding my bike. Many people give up before truly becoming fat adapted – it’s not easy, and your performance will suffer while you are getting there. I remember that vividly, and even blogged about it.
My reasons for starting a ketogenic diet had nothing to do with athletic performance. I started this lifestyle to give myself every chance possible to avoid dementia. Since starting over 2 years ago, I’ve learned I’m also giving myself a fighting chance to avoid cancer, Parkinsons’ disease, and many other autoimmune diseases caused by inflammation. Improved performance on my bike was an added benefit I wasn’t expecting.
My point is, your reasons for adopting a ketogenic lifestyle make a huge difference in how you approach it and whether you stick to it. I had strong reasons for doing so, and I was willing to suffer through poor performance on the bike because I believed in the science and I know it would get better. I had no idea how much better, but I did my research and stayed strong.
People who lament the fact that they can’t have birthday cake at a celebration may not be truly committed to a ketogenic lifestyle for the rest of their life. I couldn’t care less about eating a piece of cake. But if I did, because I’m fat adapted, I would be able to get back into nutritional ketosis very quickly (and yes, I’ve tried it with other foods, just not cake!). But again, the key is that my body is fat adapted and has been for a long time. This allows you the flexibility to fuel from carbs if needed, and then get back into burning fat.
Once you’re clear with yourself on what you want to achieve, then stick to that plan for at least 6 months. After that you can start experimenting to see if there are other ways of eating or fueling that can enhance what you are already doing.