[paulpauper]

One hour of reasonably intensive cardio burns 500~600 kcal. If you have two such workouts a week it comes down to an increased energy use of 2600/(72500) = 7%. Or a large meal. Just looking at the numbers it seems spending some time at the gym is not going to do much for loosing weight. Or said differently: eating 7% less is easier.

Not sure about this. Herman Pontzer's work shows that the body adapts by burning fewer calories later, so your energy expenditure is the same. Burning 600 calories with exercise means burning 600 fewer later, like burning fewer calories during sleep or fidgeting less.

[mint2]

Not this again: “Burning 600 calories with exercise means burning 600 fewer later.” No it doesn’t. That work is highly misinterpreted.

Because it doesn’t ELI5 how body mass and composition and steady vs unsteady state actually play into it, people take away a meaningless self serving interpretation.

If you start running 4-5 times a week, I guarantee you’ll be eating significantly more and burning significantly more. Unless you’re intentional about restricting your eating, weight will most probably stay the same, but you’ll be burning far more calories.

But keen eyed reader perhaps you object with “but you’ll move less and nap on the couch more, it will balance out like Pontzer’s work seems to say!” Haha, but no. Well yes to napping, but no to balancing out. It’s literally impossible. There’s no amount of napping that makes up for 13+ miles runs. There’s a lot of people who regularly do 10 to 20 mi runs on weekends. They can literally burn more calories just in the run than a sedentary person does in an entire day. And that’s their regular routine. Take a look at Boston to see 30ish thousand examples of it.

As one example, My weight has been steady state for decades, but I started running marathons two years ago. I had to start eating an extra meal. And when I take it easy for a couple weeks after each marathon, my appetite ramps down.

And if you don’t start eating more you’ll just get injured and be forced to stop running.

Pontzers work is bad. Ask any endurance sport club and they’ll laugh at it.

[Kirby64]

I don’t think most people (besides some naive readings of that research) should come to that conclusion. The proper conclusion is that it will offset some of the calories burned by exercise through reduction in NEAT (non exercise activity thermogenesis), but not all of it. So a 600cal exercise may only have an effective net calorie addition of say, 400cal, due to reduction in NEAT.

The problem becomes when people do the naive calculation of exercise calories (Eg, I ran 2 miles so I burned 400cal, so I can eat 400 extra calories), and come to the wrong conclusion.

[mint2]

The comment I replied to stated that was the conclusion - 600 burned meant 600 saved. So apparently the misinterpretation is common.

[alecst]

So is your rebuttal to Pontzer et al that it doesn’t match your personal experience?

[mint2]

So we’re focusing on the anecdotal part to ignore the part where I point out the naive reading of his conjecture literally defies thermodynamics? I pointed out it’s literally impossible for it to work for a subset of the population.

Over a hundred thousand endurance athletes in just the USA would have to literally defy the laws of thermodynamics for the naive reading to work.

I can see why the question ignored that and focused on the personal story that went along with the hard facts and stats.

[alecst]

Pontzer's work isn't about napping. It's about your body having a set point for how many calories it burns, independent (up to a factor of +/- a few hundred calories) of how much exercise you do. For most people this is true, as their work shows. It may not be true for extreme athletes. I don't think Pontzer's team of dozens of people working over ten years misunderstood basic thermodynamics. Their work clearly points to "compensation" -- the body making up for energy it burned during the day by gently lowering the metabolism later on.

Saying "burning 600 calories now means burning 600 less later" gets the point across. It's pretty much on the money for some people. For others compensation may not be total. I guess I'm not really sure where your beef is.

[mint2]

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)

[rojeee]

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.

[alecst]

What is your interpretation of Pontzer’s data, then?

[paulpauper]

I guess I'm not really sure where your beef is.

he's being pedantic. no use bothering to argue

[mint2]

Pontzers work shows that a 150lb male, dependent on their activity they can burn anywhere between 2000 to 3750 calories on average per day in a maintainable fashion that can go on for years. I.e activity is highly impactful to total daily caloric expenditure.

Moreover, they also showed that exercise beyond that upper limit of 2.5x the base metabolic rate is very possible for temporary durations, weeks even. The extra energy comes from stores like fat and obvious is not sustainable over years.

Even at minor increases of daily exercise for sedentary people, a regular 400 calories of exercise in one study, leads to increased total daily expenditure of around 225-250 after the body is fully adapted.

If that’s not your understanding of pontzer’s works then there is nothing pedantic about my comments. But it’s understandable if you’ve been confused because pontzer has almost willfully obfuscated the actual interpretation of his groups data. Their actual data & equations versus how they message them and explain their findings is shameful.

[paulpauper]

My own experience matches closer to Potzner's work. I see some initial loss on the after exercising but the rebound is really fast. Perhaps if you keep it up everyday there can be some long-term weight loss but it will not be continuous, and if you stop the weight will come back fast.

[throwaway22032]

Isn't that kind of like saying that the tooth decay will come back real quick if you stop brushing your teeth?

Most people need to supplement their activity with exercise nowadays because otherwise their lives are very sedentary. It's a forever thing, unfortunately for those that don't enjoy it.

[sudosysgen]

Your weight is an equilibrium between calorie intake and caloric expenditure. Increased weight increases baseline expenditure, hence the equilibrium.

If you stop exercising, but keep the same caloric intake as before, yes, it will rebound really fast, because the equilibrium point will stay the same. If you want to move the equilibrium, you either need to do the exercise regularly forever, or reduce your caloric intake, or build significant amounts of muscle (fat free body mass) to increase your baseline. expenditure

[sudosysgen]

That's just not possible. You aren't going to be burning less calories during sleep after a workout, you're going to be burning more due to increased protein synthesis as your body recovers (unless the workout was very light).

Reduced fidgeting leading to 600 calories less in a day is not reasonable, either.

To drive this home, just look at professional cyclists : a lot of them have to eat 5000+ calories a day, because they burn 3500+ calories just training, on average, for years and years.

Additionally, if you work out more, you will increase your fat-free mass significantly.

In any case, Pontzer's work never seems to claim you somehow compensate against activity expenditure, it's actually a very strong independent variable in the model of the linked study?

[throwaway22032]

This is literally impossible. The calories exerted during exercise are real work done.

Athletes exist and are real. They are not all genetic anomalies. Most of us are normal people that got off our arse.

Literally every person who has ever tried to make a weight band is living proof.