I know if you're dawdling along you can eat pretty much anything to keep you going, but if you're putting in effort you need to take on carbs/sugars, right?

Anecdotally from a pro coach who said it varied by rider, as in one of his riders could last for hours on water and a banana, whereas another needed four gels an hour; lots of other anecdotes from amateur riders who can do 80 miles on an espresso etc. But is this non-reliance on taking on carbs in-built/genetic or can it be trained into everybody?

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    There are many (many) studies on this: Go to pubmed (ncbi.nlm.nih.gov/pubmed) and search for "fat oxidation" or "fat utilization" and "exercise". As exercise intensity increases there's progressive utilization of carbs in favor of fat. Above 60-70% of VO2Max intensity, it's almost all carbs but there's no level where it's almost all fat. There is evidence that carb/fat utilization is trainable, a little. Training to raise VO2Max lets you spend more time (at the same power output) below 60% so you burn more fat.
    – R. Chung
    Feb 16, 2020 at 16:29
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    The book Cycling Science (2017), edited by Stephen S. Cheung and Mikel Zabala, has a 18-page chapter on Cycling Nutrician by Dina Griffin. It amplifies and details the above comment by R. Chung. The book is very complete and up-to-date about the human-part of cycling ; it doesn't deal with the technology and physics of bicycles. Feb 16, 2020 at 17:34
  • That book looks interesting, and comprehensive - is it all fairly cutting edge stuff, across all the chapters? I wouldn't really want to spend on a book to find that a lot of it is opinion or has been debunked á la thin tyres are faster etc.
    – Wilskt
    Feb 16, 2020 at 18:29
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    If people here are unable to answer, I would consider cross-posting on something like the biology stack exchange site. In my perception, the posters here tend to know how to work on bikes. Avoiding bonking by regularly eating carbs could be the extent of our physiological knowledge.
    – Weiwen Ng
    Feb 16, 2020 at 22:19
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    @mattnz Actually, a lot of endurance running is done at a relatively small range of pace; cycling tends to vary quite a bit more in power output because of terrain and wind, plus we have power meters on bikes while (until recently) runners have lacked similar power meters in their shoes. Laboratory cycle ergometers can measure power, while lab treadmills only measure speed. Accordingly, a lot of the nutrition and substrate utilization studies are done with cycling ergometers.
    – R. Chung
    Feb 17, 2020 at 0:27

1 Answer 1


Look at the work of Jeff Volek https://scholar.google.com/scholar?hl=en&as_sdt=0%2C5&q=Jeff+Volek&btnG=

Rethinking fat as a fuel for endurance exercise is one of his many papers, also Metabolic characteristics of keto-adapted ultra-endurance runners

He has also writen a book The Art and Science of Low Carbohydrate Performance

Low-carbohydrate diets for athletes: what evidence? Is likely to be cited by most recent papers.

These days most of his work is in Type2 diabetes, hence I dont' think he has published much on sport since his book. Some of his sport research was done with static bikes using professional long distance cycleists.

Ignore any research that had people on a low carb high fat diet for less then a few weeks before measuring performance as it is a common error other researchers make.

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