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Comment by scott_w | Hacker News Reader

You can't even explain your position to me and I ran 23km on Saturday without feeling depleted at all. I regularly bike over 100km without being depleted. I race middle distance triathlons and the only time I run out of energy is when I stop eating carbs.

You're talking absolute nonsense.

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I think OP is referring to people with poor metabolic flexibility. If not fat adapted, then you have enough glycogen for roughly 1600 calories worth of running at which point you bonk and can’t continue. If you are metabolically flexible then you substantially reduce the amount of glycogen you use at the same effort as someone who is not fat adapted. If you are very fat adapted then you can basically continue indefinitely at sub aerobic threshold pace as long as your muscles are strong enough to support you. I also have a low carb diet. It works very well for me. I was metabolically tested and burn roughly 2g of fat per minute at aerobic threshold which is pretty insane. It gets lower as you increase pace as body switches over to glycogen and then anaerobic respiration. People on high carb diets won’t get anywhere near close to that. My Aerobic threshold is >85% of VO2max (anaerobic 95%) and I can keep that up for hours even when apparently glycogen depleted (as restricted carbs in the preceding days). My running has improved immensely since going low carb - run faster with less effort and recover much faster.

Obvs if I’m racing then I use carbs.

I might add that if I’m racing or doing high intensity work, then clearly I take carbs like everyone else.

I think that’s different. There are people who can do what you say, eating less carbs, but mostly they’ve been doing that their entire lives. It’s not something you can build a training and fuelling strategy from.

Dylan Johnson does a great dive into fasted training on YouTube, which I’d highly recommend.

Thanks for the recommendation - will have a listen today.

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