I am recently back from a fairly challenging 15-day summer backpack along a section of the Pacific Crest Trail, one covering 555-kilometers (345-miles) through central and northern California. If you follow HumanaNatura, you may know that extended walks of this kind are a regular occurrence for me, and something I encourage for anyone who is able.
What was different this time, however, is that I did the entire walk eating ketogenically, or with a very low carbohydrate intake and primarily burning ketones or fats for energy. Since ketogenic exercise at this level is still unusual, and because there remains quite limited material on ketogenic eating amid strenuous exercise and other demanding physical activity, I wanted to use this opportunity to summarize what I did and experienced. Hopefully, the discussion will be helpful to you and, as importantly, encourage researchers to explore intensive exercise and sustained activity amid intentional ketosis.
Looking South Across A Very Smokey Sonora Pass In Northern California
Before beginning our discussion, let me emphasize that I did this extended keto-enabled walk after a significant time of eating and exercising ketogentically in my regular life (technically, eating phyto-paleo-keto, or a diet that is plant-rich; free of grains, legumes, and processed foods; and then further largely free of fruits and starches – see here and here for examples of my typical once or twice-daily meals). Because of this, I had given my body sufficient time to become keto-adapted or able to readily (and naturally) use fats as my primary energy source.
Importantly, regardless of how physically fit you are or may become, I would recommend not engaging in strenuous or extended exercise on a ketogenic diet until you are fully keto-adapted (this normally takes a month or more), reasonably experienced in ketogenic eating overall, and have successfully exercised more moderately on a ketogenic diet for a number of weeks. I would also recommend avoiding alcohol entirely while eating, exercising, and living ketogenically, as is my practice.