Comment by deepnotderp

1. Phelps seems to be guessing: "Maybe eight to ten thousand calories per day," he writes... Also, the research shows there is extreme variation in people's resting BMR (perhaps due to large variation in height, body weight, stress levels, etc), so you eating 3500 calories isn't decisive against the thesis of this article.

2. That is exactly his hypothesis, and he has produced evidence for this hypothesis in a recent experiment. I don't know why you are presenting this as some kind of counter-argument.

3. That blog post isn't a coherent critique. The post's two points are that the drinking solution is also used for measuring energy intake, and that the Hadza actually burn far less calories than Western people until such numbers are adjusted. This first point isn't relevant without further explanation, and the second point only serves to further support the thesis.

> From a simple sniff test, if this were true, then athletes wouldn't need a lot of calories.

That was my first thought as well.

It's even more evident with certain types of sports. Take cycling for example. Lifting mass up a mountain is going to take quite a bit of energy; maintaining a constant speed in the face of wind resistance will take energy. That energy has to come from somewhere.

> 1. then athletes wouldn't need a lot of calories.

Some don't. Think about marathon runners (which would be pretty close to the tribe studied), they have a muscle ratio that is way lower than your Phelps example and their body composition if also probably more efficient than yours (I don't know you, but let's assume). I wouldn't be surprised if a pro marathon runner would have be close to your 3.5K a day when going through light training.

Think of it through different angles: mountain trekkers aren't packing 80kg of sugar to go through their trekking, their bodies are way more efficient at doing these tasks and need less calories to work than what we'd expect from a random person. It literally means doing more with less.

> This often happens to people trying extreme calorie loss diets.

This happens to everyone. From your link: "In fact, your body is hard wired to maintain energy balance within a fairly small range."

> 3.

It seems well argued but just really nitpicky. It goes into the whole energy intake vs energy spent debate to explain why they don't agree with the methodology, but don't prove why they think the conclusion is wrong. It's as if I'd nitpick your use of calorie intake measurements and explain in great details how it's approximation of an approximation and we have no way to actually know someone's actual intake calorie, without ever engaging with your actual points.

> 1. From a simple sniff test, if this were true, then athletes wouldn't need a lot of calories. This obviously isn't true, eg Phelps eats 8-11K calories a day. I personally eat around 3.5K calories a day. If exercise didn't impact caloric burn I assure you I'd be a lot fatter...

I agree and I'm in the same boat. After 10 years of running ~70km/week, I'm eating way more, have dropped 20lb, and am healthier and stronger.

> The implication of this is that somehow the sedentary lifestyle of your average couch potato is the "normal" lifestyle for a body, and the lifestyle of a hunter gatherer is "overactive", and their bodies are chronically tired and trying to reduce their metabolisms. That... seems quite unlikely.

I think people underestimate what being active and excercise actually mean. Our ancestors were vastly more active than we are today. The amount of movement that was required for foraging, hunting, agriculture is hard for most modern people to imagine.

Even the act of preparing the food that was gathered/hunted/harvested was so much more manual and energy intense than what we are accustomed to today.

For most of our evolutionary history basically everything we did was powered by our bodies. Today we have machines for everything, and a high standard of comfort.

It's true that calorie restriction is easier for most people than excercise, but I think it's because.. to put it bluntly.. we've become lazy.

>> somehow the sedentary lifestyle of your average couch potato

What I got out of the article wasn't that sitting still and not thinking can somehow burn calories; just that strenuous mental activities can burn a great deal more energy in humans than in apes. This is believable to me. I'm a person who falls asleep doing math in my head every night. I got a chance, during a year of pandemic lockdown, to experiment with my own body in this way.

I only eat once per day. I don't keep fixed hours; sometimes I'll stay up for 24, sleep for 16; other times I'm regularly 8/16 sleep/wake. I don't have a set bedtime. I try to maintain 16/48 sleep/wake over any given period.

No matter what, I only eat one meal every 24 hours. I've been doing this for about 20 years.

This makes it easy to measure when I get hungry in relationship to my last meal. My body is well trained to expect about a 24 hour delay; I have no appetite and don't think about food until around 22 hours post-dinner.

Under lockdown conditions, I began to notice that I wasn't hungry as expected on days where I hadn't spent >= 6 hours working on strenuous code. If I took a day off and "couch potato'd", I might not eat at all for 48 hours. But if I focused on code for 8+ hours, I would be hungry on time or early.

I started to experiment with this. I figured out that if I took a 1 hour walk, plus 4 hours programming, it made me hungry right around where 6+ hours of code did. A 1 hour walk - to me - seems about equal to 2 hours of writing code in terms of what my body feedback gives me about my calorie burn.

I don't walk very fast, and I code very intensely.

But that's just it - this article is about solving math problems as a way to burn calories. I have a nice new M1 Mac that only ever turns its fans on or gets warm when I'm using all 10 cores. Last night my task falling asleep was to calculate randomly chosen x/128ths as percentages to five decimal places. My daytime task was harder; and now I'm hungry. And I haven't walked anywhere today.

However: Couch potato, this ain't. And the point about the body's reduced expectation of physical output is probably accurate as well.

Yes, those marathon runners mentioned might reduce their TEE from 6200 to 4900 kcal/day. But that is still way more than most office workers eat.

And if you check the article:

https://www.science.org/doi/10.1126/sciadv.aaw0341# == The reduction in TEE among RAUSA subjects can be partly attributed to marginally reduced body mass and daily mileage (table S3). Still, even after accounting for these changes, Week 20 TEE was 596 kcal/day lower (range, 400 to 923 kcal/day) than expected ==

So they did loose weight during the marathons and the metabolic compensation is less than half of what you would think reading the original article.

== ... The magnitude of metabolic response in RAUSA athletes (~600 kcal/day, ~20% TEE) is similar to the degree of adaptation reconstructed for the most physically active subjects in a recent cross-sectional study (17) and may reflect humans’ maximal capacity for metabolic compensation. ==

So if 20% percent is the maximum, it means that if you try to outrun your diet, you might have to eventually exercise 25% more. Except by then you will probably have more muscle mass that will burn more calories even when not exercising. And you will be able to exercise more in less time.

Suddenly it does not look so hopeless.

I don't think you read it properly ... what I got from the article is that there is large energy compensation happening, but it's not endless, there is a threshold.

Ie. scientists wouldn't think that average Hadza hunter burns same calories as average sedentary guy from US ... which is the point of this new discovery ... the lifestyle is different enough that you would not think the expenditure will be similar. We always knew there is compensation happening, but we didn't think that much.

But, if Phelps burns 8k calories ... then he perhaps far far exceeds the amount of exercise the average Hadza hunter outputs ... at that point, the body can't just shift some energy expenditure around and compensate for it .. it will in fact need lot more energy to support the physical output.

The article even proposes what the ceiling of input calories (and therefore sustainable output expenditure) is. 4650 cal for 85kg man. So obviously, it doesn't claim that every human on the planet burns the same amount of calories no matter what they do. It only claims that for example energy requirement differences between somebody who outputs 200kcal or 1000kcal in exercise are nearly erased because the body compensates on the BMR. Obviously there is a hard limit on how much body can compensate and save energy by cutting it from other processes.

I think the debate has been settled a long time ago:

https://www.bmj.com/content/349/bmj.g7257

Don't forget Phelps also spends most of his exercise time in water. The body expends energy to maintain thermal equilibrium, and water absorbs heat much more quickly than the air. With several hours of swimming each day, that energy will add up.

I do think the point is also partly that what most people consider 'a good amount of exercise' isn't really very strenuous. Doing a bit of cardio and weights at the gym 3x a week isn't enough to offset a bad diet. If you run 10k every day, that's a very different ballgame because you meaningfully burn more calories than a regular diet gives you.

It's also incredibly easy, at least in America, to consume way too many calories. To meaningfully lose weight you have to drastically change your diet or drastically up your movement.

But, surely the researcher is aware of people like Phelps. It wasn’t addressed in this article for the masses, but I wonder if he addresses people like Phelps in his actual research papers.

About Phelps - he need to build, maintain and condition a whole lot of muscle mass.

He’s incredibly far from a normal human - he’s a true specialist.

Lots more energy goes in to that, compared to losing excess fat and living a “normal” human hunter gatherer existence.

The whole system change once you go google scale, so to speak, and phelps is gmail.

In the words of Ido Portal: we’re human first, movers second and specialists last.

I see relevance in this research in the human/mover perspective.

> If exercise didn't impact caloric burn I assure you I'd be a lot fatter...

Simply having more muscle mass can burn calories too. Most people don't spend most of their time training either, so comparing to elite athletes is fairly irrelevant.

Swedish speed skater Nils Van Der Poel drinks cream and eats crisps, LOTS of it, while training just to get enough calories in his body to continue training so number 1 is faulty.