In 5 years of blogging, I've intentionally steered clear of writing about how to fuel when running. The reason: diet is the refuge of the lazy athlete. Everyone would like to believe they can improve, not by training more, or harder, or smarter, but by swallowing something. "You like to eat; you hate to work - I get it - now let me get back to business." My belief has always been that the body will adjust to almost any type of fueling and it's simply a matter of preference, that no one diet is inherently better than another; it's time to see if I can justify that.
There are three pure strategies of fueling. The first is the Constant Supply model, the current standard, where one ingests carbohydrate continuously during exercise. Among ultramarathoners, the prime example is Yiannis Kouros; during the Sydney to Melbourne 960K (600 Mile) race, he ingested 7800-13770kcal per day and expended a calculated 7736-15367kcal, with a 5 day total of 55970 ingested, 55079 expended. [Rontoyannis, 1989, quoted in Noakes' "Lore of Running"] His fuel was 96% carbohydrate. It is interesting to note that Noakes has published that one can utilize only one gram (4kcal) of carbohydrate per minute, when ingesting at least 70-100g per hour [citing Hawley, 1982; Wagenmakers 1993; Saris, 1993].
The second pure strategy is the Constant Deficit model, following a ketogenic low-carbohydrate diet. Perhaps the best ultrarunner currently touting this is Zach Bitter.
The third pure strategy is the cyclic Feast and Famine model, which I fell into through habit and inclination. This method alternates periods of high carbohydrate load with periods of low carbohydrate supply.
There are also mixed strategies, which complicate matters. For example, many marathoners will use the Feast and Famine model only in the week leading up to a major race.
What I hope to cover in the next posts is how the body utilizes fuel during exercise, how one can alter that through diet and/or exercise and what that means for anyone trying to optimize race performance.
I expect the answer will not satisfy anyone.
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