Back in 2011, famous Primal Blueprint guru Mark Sisson wrote a post about how he’d train for a marathon. Mark’s no novice when it comes to distance running: He is in fact a former marathoner! His conversion to the lower-carb, paleo-style Primal approach to eating and lifestyle is in no small part a byproduct of his experience training to race the longest run.
Sisson of course generally discourages any sort of endurance training, prefering a more biologically natural sprint-and-saunter approach to outdoor activity akin to our prehistorical ancestors. Like many paleo-minded humans he’s more into occasional high intensity low duration activity surrounded by lots of regular but very low intensity activity.
This level of activity is of course a better fit for a lower carb Primal style diet, as endurance training traditionally requires a very high carb intake… intake that Sisson’s experience and research taught him can be damaging to your long term health.
However, a lack of carbohydrates can compromise the quality of your endurance workouts, let alone your race performances, since your body typically utilizes glycogen for extended endurance activity.
Sisson historically has preferred to avoid endurance training entirely and focus instead on what he’s found to be a more long-term sustainable lifestyle. His 2011 piece was more of a hypothetical, ‘If I had to train as a Primal disciple to run a marathon this is how I would approach it.’ Sisson’s piece definitely hinted that he had far more intel behind it, and that there was probably a book in him on the subject.
Well, eventually he did write that book. Primal Endurance by he and Brad Kearns spelled out the ideal combination of the Primal diet and lifestyle with the ideal training approach to maximize your performance in a marathon without the usage of carbohydrates and their glycogen.
I’ve given the book a gradual read over time, and while a lot of it reads like sales-letter filler for the Primal Blueprint (which seems superfluous since you probably aren’t reading the book unless you already own, have read and believe in the Primal Blueprint), what remains after filtering through it is a compelling and well-written approach to training as a Primal endurance athlete.
Sisson of course is hardly the only believer that endurance athletes can succeed with a lower-carb approach. Many ultra-runners have sworn by training low-carb to train their bodies to maximize fat usage in their excessively long races. Other non-ultra runners have sworn by training low-carb as well (I even know a few!).
I’ve long since argued (as many do) that accepting this lifestyle and swearing off most carbohydrates does to some degree limit your capability as a distance runner. In principle, I still find that to be true.
But there’s no denying that long term the endurance diet and lifestyle does take a toll on your hormones and to an accordant degree your health. I recall half marathon champ Ryan Hall being forced to retire in his early 30’s due to wanting to start a family and his training lifestyle compromising his body’s ability to do so. Sure enough, once he stopped running, his health rebounded.
I do think there’s a middle ground, mostly that you train in cycles and that you take breaks from training and the diet it demands. However, Sisson and Kearns argue that their recommended lifestyle can be practiced year round, in and out of training, without damaging your race performance.
Matt Fitzgerald’s book 
