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by oezi 1235 days ago
One key thing to remember is that humans can't do much more than 30 hours per week of exercise because they can't consume sufficient calories to compensate.

It has come to the point that tweaking nutrition science to feed athletes better so they can train more is a key aspect of the ultra endurance training (e.g. the Norwegian Iron Men around Olaf Alexander Bu).
1 comments
tayo42 1235 days ago
That's 4 hours of activity a day. That can't be true. I do that. I should be fading away then but hover at the same weight.
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oezi 1235 days ago
4 hours of strenuous exercise. This should consume around 3000 kcals.

Studies have found that humans cannot consume more calories than 2.5x their basal metabolic rate.

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petesergeant 1234 days ago
Do you have the source for this? I tried ChatGPT:

>> Someone on the internet wrote "humans cannot consume more calories than 2.5x their basal metabolic rate" -- which study might they be quoting?

> I am not aware of a specific study that states that humans cannot consume more calories than 2.5x their basal metabolic rate. Basal metabolic rate (BMR) is the amount of energy a person needs to maintain basic bodily functions such as breathing and digestion, and it can vary greatly depending on factors such as age, sex, and muscle mass. However, the total daily calorie needs of an individual also depend on their level of physical activity and other lifestyle factors. So, it's likely that this statement is a generalization or an over simplification.

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oezi 1234 days ago
https://www.science.org/doi/10.1126/sciadv.aaw0341

"Incorporating data from overfeeding studies, we find evidence for an alimentary energy supply limit in humans of ~2.5× BMR"

A good book the topic is Herman Ponzer's "Burn"

The main issue seems the surface area of the GI tract.

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petesergeant 1234 days ago
Fascinating, thank you. Apparently this means the most I can gain over Xmas week is 2.45kg, which is reassuring.
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sasawpg 1235 days ago
During aerobic training, Nils van den Poel would average 33hrs/week (3x7hr, 2x6hr) roughly at 250W, which will be in the vicinity of 850-900kCal/hr depending on his body's efficiency, likely around 24-25%. That averages to 4250kCal/day when spread across the week. At his size and fitness level, he is probably in the 1800-2000kCal/day range for metabolic basal rate. He aimed for 7000kCal/day during aerobic training and gained 5kg during that summer on purpose. Math seems to add up to me.
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tayo42 1235 days ago
You have to misinterpreting something. 2.5x is 4750 calories total. Athletes are eating more then that.
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oezi 1235 days ago
The key insight is that you can eat more, but your body will not consume it.

https://www.science.org/doi/10.1126/sciadv.aaw0341

And nobody is saying you can't expend more energy for shorter times. It is just that you can't sustain it over long times because of our metabolic limits.

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