Comment by idontwantthis
3 years ago
> it never really worked because I’d unconsciously eat to compensate
The wild thing is he’s saying that’s not true either. He’s saying you never burned the extra calories in the first place.
3 years ago
> it never really worked because I’d unconsciously eat to compensate
The wild thing is he’s saying that’s not true either. He’s saying you never burned the extra calories in the first place.
That’s the part that’s at least slightly exaggerated, or giving a misleading impression. Exercise absolutely burns more than 0 calories, and I definitely was burning some. Calorie burn from exercise is straightforward to approximately measure, and many people walking around with iWatches and FitBits and heart monitors are doing so. What’s well known to many people is that exercise burns far fewer calories than you wish it did, and less than it feels like. ;) The article points out that aerobic exercise adjusts your RMR and it becomes more efficient over time. However, it does not become 100% efficient, even though the article seems to suggest it and doesn’t bother with any fine print. It doesn’t bother to differentiate between running and weight lifting either, and we adjust to those differently.
I would really like to see raw data because it feels like the story being told can’t possibly be complete.
This in particular feels really hand wavy: “After weeks of training, they barely burned more energy per day when they were running 40 kilometers per week than before they started to train.”
What does “barely” mean? 40km/week isn’t that much in terms of calorie burn. The 100 calories/mile rule of thumb says this would imply ~350 calories/day. And this article says a woman would have a daily calorie expenditure of 2400 already (seems high, though). So this is only 15%. But anyway, this drops after adaptation seemingly, so does “barely more” mean 50 calories/day? Or does it mean 300? Because those are very different. And to where is the difference attributable? Because someone going from sedentary to trained runner is going to get a lot more efficient at running. “Less energy on inflammation” is really hard to swallow as the primary source of adaptation, especially when this is presented as conjecture.
It does seem like the article is exaggerating. ;) This could be more about the author presenting a narrative than Pontzer’s data. Bringing in the sports physiologist to argue for the idea of exercise without countering the caloric claims adds a little perhaps predictable dramatic flair.
At some point, there’s just physics. Running a mile isn’t free, benching 100kg isn’t free. These things take work and we can calculate the minimum energy requirement that adaptation can’t escape. Our bodies do not adapt so far that exercise becomes pointless, it only shifts the balance a little (which might be enough to be demotivating for some people, but it’s still relatively minor.) I was under the impression that the total range of metabolic adaptivity for a given person might be on the order of 25%-30% maybe. That might be an over-estimate. I googled a little and found this paper mentioning adaptations of like 8%-15% for severe calorie restriction diets (depending on how RMR is measured).
https://academic.oup.com/fampra/article/16/2/196/480196
40km/wk is only 3.4 miles/day. It's only a half hour of moderate exercise a day. It sounds like the study didn't actually measure a significant exercise workload.
3 replies →
Not sure why you’re getting downvoted. That is literally the thesis here, that calorie expenditure is essentially decoupled from exercise.
Which is laughably ridiculous when you start considering the extremes like Michael Phelps eating 10kcal for breakfast.
The issue is the uptick in energy burn is unintuitive especially in the world energy dense high-processed food
As an ex once put "you have to run 5 miles to earn a cupcake - totally not worth it!"
> Which is laughably ridiculous
We're glad you're here to poke fun at the research of at least two people with PhD's centered on this topic.
> when you start considering the extremes
When you start considering the extremes, you often find that they can't tell you much about the middle ground.
2 replies →
> Which is laughably ridiculous when you start considering the extremes like Michael Phelps eating 10kcal for breakfast
I think you are missing the fundamental part of the article about the calorie expenditures being adjusted based on non-fat body mass.
So, yes Michael Phelps eats a lot of calories, but him (and other pro athletes) have spent their lives building muscle and keeping fat reserves down. Michael Phelps I think is at a 5% body fat, while the average American is 18%+. He needs more calories for that extra body mass that most people the same height don't have.
1 reply →
Total body calorie expenditure seems decoupled.
Exercise obviously must burn calories because work is being done. The body can’t overcome physics.
The nuance, and the surprising thing, is that other parts of the body seem to adjust their energy levels to compensate. If you don’t do a lot of exercise, something else burns calories. If you do exercise, the “something else” burns less.
What is the something else? That’s the mystery that still needs to be solved. And by extension, what are the limits of the something else? After all, there are well-documented examples of extreme athletes who consume lots of calories without gaining mass.