Comment by themodelplumber | Hacker News Reader

Comment by themodelplumber | Hacker News Reader

themodelplumber

> Exercise doesn’t help you burn more energy on average; active hunter-gatherers in Africa don’t expend more energy daily than sedentary office workers in Illinois; pregnant women don’t burn more calories per day than other adults, after adjusting for body mass.

I love this intro.

> His message that exercise won’t help you lose weight “lacks nuance,” says exercise physiologist John Thyfault of the University of Kansas Medical Center, who says it may nudge dieters into less healthy habits.

This is funny to me because my own logs reflect this going back to about 2015. I can more easily drop 10, 20, or however many pounds when not exercising than I can when exercising. That was a really weird one because it opened up a bunch of other problems.

One follow-on problem that came up quickly: How to develop skills requiring fitness during those times, or how to maintain endurance levels when you're intentionally lowering your exercise exposure so you can lose weight. That kind of situation is pretty interesting.

> Azy, a 113-kilogram (249 lb.) adult male (orangutan), for example, burned 2050 kilocalories per day ... When adjusted for body mass, (humans) burn ... 60% more than orangutans

Oh and

> “She burned 40% more energy per minute in the math test and 30% in the interview,” Pontzer says. “Think about any other process that boosts your energy by about 40%.”

This is really curious and fascinating stuff. Thanks op for posting.

PS:

> He calculates that the ceiling for an 85-kilogram man would be about 4650 calories per day.

Combining this with the fact that Everest climbers are apparently eating 10K+ calories a day and then up to around 20K on summit day, I have to wonder how these facts jive...if they can really temporarily push the limit, for how long, etc.

> Combining this with the fact that Everest climbers are apparently eating 10K+ calories a day and then up to around 20K on summit day, I have to wonder how these facts jive...if they can really temporarily push the limit, for how long, etc.

An interesting source here is the Fiennes and Stroud expedition to cross Antarctica in 1992. Stroud (a physician) actually tested how many calories they were burning each day using the doubly-labeled water method, and at one point (ascent to the polar plateau) it was up to 11k. So it is definitely possible to temporarily push the limit - as the article acknowledges - but these are exceptional circumstances.

Another related extreme case was the first person to solo-ski to the north pole. They pre-loaded, mostly on olive oil, packing on tens of kg in body fat, all of which (and more) was gone by the time they were done. I don't recall the daily calorie expenditures but it was gigantic. They did this because there is some mechanical advantage carrying a good chunk of one's energy supply directly on your own bones rather than towing it in the sled.

Fiennes and Stroud lost about 25kg each crossing Antarctica; I don’t know if they pre-loaded beforehand (hopefully they did, losing that much!) but they certainly ran a deficit as a strategic trade-off against their sled weight. Hauling a kilo of fat on a sled is definitely less efficient than carrying it on your own body.

Supposedly their calories during the expedition were primarily from butter, which they mixed into every food and even ate on its own. Apparently you get used to it.

Some friends and I are currently doing a thru hike of the Appalachian Trail, and only ten days in the four of us clocked 7, 8, 10, and 17 pounds lost... But we're hiking 6+ hours a day with heavy packs. We've been eating easily ~3000kcal each daily. I think at the extreme edges, nutrition science is a lot less well understood. We were very surprised to see we'd lost anything at all, as we're stopping to eat 300 calories almost every waking hour.

6hrs a day @ 3 mph = 18 miles per day, 100 calories per mile without packs = 1800 calories per day on top of basal metabolic needs. Given your user name, I'd guess that you're male, and given that you're hiking the AT and have already started, I'd also guess that you're younger rather than older, so I'd peg your basal metabolism at around 2200-2400 calories. Add in the packs and the hills, and it should be clear why you're losing weight.

A lot of an initial 10 pounds of weight loss can be dehydration and less food in the process of digestion.

That's a good point.

Seems early to start the thru hike. How many people are on the trail?

It's already at least 10 people at each shelter every night. There's ~60 people scheduled to leave on 2/22/22, and ~60 on 3/1/22. It's going to be real busy real soon, this year will be packed by March.

We're taking it pretty slow and getting off trail whenever the weather turns sketchy (like last night possible thunderstorms). The real part we're concerned about is getting over the Smokies without getting stuck up there in the snow.

> Combining this with the fact that Everest climbers are apparently eating 10K+ calories a day and then up to around 20K on summit day, I have to wonder how these facts jive...

The estimate is probably off for extreme circumstances and those people probably aren’t fully digesting and using all of those calories. The accurate number would be interesting.

I too have found that cardio isn’t very good for dropping weight, but packing on some muscle does a lot to shift body composition. Maintaining more lean mass simply requires more calories.

I'm baffled by the take away from the study. If a sedentary person and an athletic person burn about the same, doesn't that just mean the sedentary person's energy is being spent on maintaining and accumulating fat mass? But why is that waffled about instead of stated?

Major Edit: more concise example

>As the athletes’ ran more and more over weeks or months, their metabolic engines cut back elsewhere to make room for the extra exercise costs, Pontzer says. Conversely, if you’re a couch potato, you might still spend almost as many calories daily, leaving more energy for your body to spend on internal processes such as a stress response.

If storing fat burned calories, it would make for a pretty poor way to store calories...

Cells don't live for free and fat is stored in cells. So yes storing fat burns calories, just far less than muscle. And that's just the direct expenditure.

I see a few numbers thrown out for how many calories a pound of fat burns a day, but that direct burn is only one way additional fat would lead to energy use. A heavier person while less "active" will burn more during day to day due to carrying a heavier mass. I'm sure there's plenty more ways but I'm not going to go do a deep dive.

> Combining this with the fact that Everest climbers are apparently eating 10K+ calories a day and then up to around 20K on summit day, I have to wonder how these facts jive...if they can really temporarily push the limit, for how long, etc.

I think a lot of these stats are myths meant to accentuate the difficulty of the task. Pontzer’s book discusses Michael Phelps and the lack of an actual source to the rumours he was eating gargantuan amounts during training.

Michael Phelps directly says in one of his auto biographies that he was eating 8-10k calories a day. I don’t think you can call that a rumor.

Of course he could be off a bit, but it seems unlikely that he’s off by a factor of 2.

He lists the foods that he ate, and it definitely sounds like it was close to 10k calories. His coach also discussed his diet, and backs up his claims.

So I'm not sure about everest climbers, 20k sounds pretty crazy.

But I can speak first hand as a former athlete who has had access to NFL players and Olympians. 8-10k during peak active training happens all the time

Long term average might be 4-5k.

You have to remember that these people are often on PEDs that allow them to train all day.

Shit I was a serious powerlifter back in the day and would routinely eat 6-7k calories (weighed) during 2adays depending on how my weight was fluctuating. Add some more height, PEDs, and cardio and I'm almost there.

I think the difference between what is mentioned in the article is #1 obviously PEDs #2 body breakdown and recovery, which might be more in e.g. lifters and swimmers than long distance runners

I've read a decent number of books about climbing big peaks. In all of them they said they were so nauseous on summit day from being in the death zone, they could barely force down a protein bar.

I believe him. As a nowhere-near-olympics division 1 swimmer, I had developed a major weight loss problem my freshman year. I actually was required to log my calories and meet with a sports nutritionist weekly. After 6000 calories a day, I was shoving so much food in my mouth, I felt like it wasn't possible to eat any more than I did. She prescribed Snickers bars as a way to top off my calories every day without contributing too much to feeling full. I was targeting 7000 calories a day, and I don't think I ever consistently reached that goal, but around that time my weight stabilized.

There are a lot of people who maintain a high degree of fitness, and for them I can imagine 4000 calories is about right. But there are some types of training that are consistently pushing your physical limits. I don't have any sort of data to back this up, but it has long been my theory that the reason why elite athletes can burn so many calories is because they aren't actually burning them in the traditional sense of cells oxidizing chemical energy to create work...they've crossed over into the territory of muscle tissues being torn up and resynthesized so much that your body can no longer do so efficiently.

As an analogy, typically in manufacturing there are always efficiencies that can be extracted. But in very mature industries where there aren't any easy efficiencies to eek out of the system, you have to start making tradeoffs. One common tradeoff is throughout vs yield. You can increase your throughout, but in order to do do so, you have to cut corners on processes and subsequently increase the total amount of waste in the process.

And as a "maybe this is related" data point: 82% of marathon runners suffer from Acute Kidney Injury. Your kidneys have one job: waste disposal. It would be easy to infer that at the boundaries of human conditioning, the kidneys aren't up to the task of processing all of the waste that the body is producing.

https://medicine.yale.edu/news-article/marathon-running-and-...

> Combining this with the fact that Everest climbers are apparently eating 10K+ calories a day and then up to around 20K on summit day, I have to wonder how these facts jive...if they can really temporarily push the limit, for how long, etc.

Yeah, I'm not convinced the article passes the smell test.

Michael Phelps discussed his diet extensively, suggesting he ate 10k a day while training. Other athletes talk about similar meal sizes. This suggests that once they stop exercising (thus eventually losing lean muscle mass and requiring less calories) that they would not see a change in their weight, yet there are a lot of old fat athletes (possibly just of a certain generation) out there.

They could just be shitting out the excess calories, and the article directly says,

"Elite athletes can push the limits for several months, as the study of marathoners showed, but can’t sustain it indefinitely, Pontzer says."

Where are you getting those numbers for Everest climbers? I have a very hard time believing them.

High altitude suppresses appetite in general and your body does not get enough oxygen to meaningfully process food above about 25,000 feet. Everest summit day via the South Col starts at about that altitude.

Plus it’s freezing cold and everything takes forever to do. I don’t think there is much eating at all on Everest summit day, let alone 20,000 calories.

Napkin math: 20,000 calories is 36 Big Mac burgers

In vegetable oil it would be about 4.8lbs of oil - that’s probably not at all plausible for digestion or bowel control

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