For hundreds of thousands of people it’s not true. That is not an exaggeration in numbers.
Handwaving away large numbers data points that disprove a theory is not how science is supposed to work.
And as we have seen in this thread, the lack of clarity on the nuance discourages people from making exercise.
Over simplifying it to 600 burned, 600 saved later is harmful and also inaccurate. (and yes More inaccurate than my loose choice of saying nap which you pointed out that led you to the wrong conclusions on my understanding, please consistently apply that critical standard)
Also an endurance runner and read Pontzer's book. I do enough running for my wife to get pissed off! I agree with you that there's definitely more work which needs doing to understand metabolism in the context of endurance athletes. I don't think his work is outright nonsense though. Here's something to think about...
I ran 21 km yesterday, in zone 2, in a fairly glycogen depleted state. That was about 4:30min/km for 21km, with 600m of elevation - about 1500kcal of energy. I didn't eat or drink anything throughout the run. I'm a big nerd, so I took a lactate sample at the end. I didn't hit the first ventilatory threshold for the whole run and that indicates I'm burning a large proportion of fat compared to a normal person (and probably a normal recreational runner).
Afterwards, I ate a banana and had a couple of spoons of peanut butter + honey. A few 100kcal. Fast forward to the evening. I didn't eat any more than I usually would do if I had a few days off running. I went on with my day as normal and recovered fine the next day. I didn't feel hungrier than usual. Fairly standard. My body is well adapted to this kind of exertion. I think my body is quite efficient at doing every day things. I don't get out of breath walking up stairs, for example. Maybe it's fair to say I'm more energy efficient than a regular person. Perhps, I don't need to eat any more than usual immediately after running because I'm burning a high proportion of fat and my metabolism is quite efficeint anyway.
Someone who has a poor aerobic system wouldn't be capable of doing that. They'd likely be running at a much higher heart rate and bonk after 10km having not eaten any carbs the day before. They'd also likely need to eat a huge bowl of pasta afterwards just to feel OK. I suspect this person would feel like crap for the rest of the day (maybe even multiple days... Imagine.. they've likely just done a 10km at VO2max untrained) and I could completely imagine them having a nap or watching TV for the rest of the day as they'd have no energy to do anything else. Their bodies are not adapted to this kind of exertion. They are not efficient. Their body needs to rest to get back in equilibrium.
The energy requirement is the same in both cases but it comes from a different source. In my case the high fat oxidation is acting as a battery/buffer. In the average person, those fat stores are not really accessible when doing anything more than sitting or light walking. Both examples are in equilibrium but present in different ways.
This is mostly unrelated to the current point, but you’re unquestionably fitter than the average person. I used to dance for about 15 hours a week, and I have no idea what I actually burned calorie-wise, but it was plenty of cardio.
After about a year of dancing, I had a moment where I needed to run after someone about a half kilometer away. It was incredible- I’d never felt so buoyant while running. After I passed the message on, I decided to do a measured run. I ran a six minute mile in my late twenties with zero warm-up after having not run in over a decade. I wasn’t even out of breath, it was fucking easy. Cardio is a life hack.
First, note that my biggest point is that the way his group presented the work has led to gross over simplifications that actually cause harm when they help deter people from making changes, and the group has not gotten the word out that those interpretations are incorrect.
It’s pretty clear the effect of exercise is neither extreme. It is definitely not the naive 100% of calories burned in regular exercising are balanced out by metabolic reductions elsewhere compared to the same person not regularly exercising. And it’s definitely not 800 burned regularly means 800 mores than the person would if they didn’t exercise regularly.
It’s going to be in between, and I would wager it’s like backwards graduated tax brackets in terms of compensation percent.
It’s been a while since I read his paper, but if I recall right it actually did hand wave away the endurance athletes. But endurance athletes are not a binary yes no state andHand waving away obvious conflicting data isn’t logical or scientific. And so especially when people are on a graduated spectrum all the way up to the immediately obvious theory breakers running 60+ mi/week. Where would the cut off come? 15mi? 20mi? 25mi? Above what cut off should we ignore data to make the naive theory work.
Handwaving away large numbers data points that disprove a theory is not how science is supposed to work.
And as we have seen in this thread, the lack of clarity on the nuance discourages people from making exercise.
Over simplifying it to 600 burned, 600 saved later is harmful and also inaccurate. (and yes More inaccurate than my loose choice of saying nap which you pointed out that led you to the wrong conclusions on my understanding, please consistently apply that critical standard)