Holmer says fat adaptation is no longer an asset
Zach Bitter pushes back in part, saying gut training and better products closed the gap.
Brady Holmer says the old belief that being a better fat burner makes you a better endurance athlete does not survive the high-carb fueling era.
His post is short. He writes that the sport used to hold a strong ideal that fat adaptation, or training your body to burn more fat for fuel, was an asset in endurance sport. "That's no longer true in the era of high-carb fueling," he says.
That's no longer true in the era of high-carb fueling.
Bitter answers with a caveat
Zach Bitter, who has long argued for lower carb training, replied rather than objected. He says fat oxidation does improve from endurance training alone, and that it goes up quite a bit further when you combine endurance training with low carb. The consequence, he says, shows up at the higher end of the aerobic intensity spectrum.
Then he concedes the main point. The reason people chased extra fat burning, Bitter says, was to help meet energy demands in certain race types without overfueling and wrecking the gut. He now believes that gap can be closed another way, through gut training, better products and ratios, and simply taking in more carbs during the race, and without giving up performance at harder efforts.
So this is two fueling voices landing in roughly the same place from opposite directions. The reason to be a fat burner was a workaround for a stomach that could not take enough carbs. Modern in-race carb intake removed the need for the workaround.
The Noakes question
Mark Wilson replied to Holmer asking whether work from Tim Noakes on fat adaptation is still relevant. Holmer's posted thread does not include an answer in the sources here. Noakes has been a recurring presence in these fueling arguments, including his earlier doubts about how many carbs elite marathoners actually take in.
What it actually means for your long run is narrower than the headline sounds. Nobody in this exchange says fat oxidation stops happening or stops mattering. The claim is that deliberately chasing more of it, by keeping carbs low, no longer buys you anything you cannot get from eating more during the race.
We now believe that gap can be closed with minimal risk with proper gut training, better products/ratios, and higher in race carb intake
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