“Pregnancy” probably isn’t a thing. “Pregnant” people eat around 500 more calories per day. This is sufficient to explain all the weight gain from “pregnancy” without supposing anything other than thermodynamics at work—anyone who eats an extra 500 calories per day will probably gain that much weight over the course of 40 weeks.
I think Ege’s alleging that SMTM presented two causal graphs:
calories → ? → weight gain
calories → weight gain
Ege’s saying that 2 is simpler and sufficient, so we don’t need to posit a ? in the middle.
You’re pointing out that we still need to address a third causal graph:
? → calories → weight gain
Edit: And maybe that there’s also a scenario where ?, calorie intake, and weight gain are all in some complex interrelationship. Maybe contaminants cause more fat deposition and less energy and more hunger, thereby increasing weight gain per calorie, increased calorie intake, and increased contaminant intake via food. Or something.
Ege’s agreeing with you, but wants to emphasize that this is compatible with criticism of SMTM’s alleged emphasis on graph 1.
Note: I say “alleged” only because I’m sidestepping evaluating the truth of Ege’s claim. Just trying to clarify what it is (AFAICT).
I don’t agree with this presentation of what I’m saying.
I’m not terribly sure what SMTM means when they say “the increase in calorie intake is small”, but all possible interpretations of their claim seem wrong. For instance, one plausible interpretation in causal graph lingo is “if you applied the do operator on calorie intake and raised it by 20%, we would have seen an increase in body mass that’s significantly smaller than what we’ve actually seen”. I think this claim is wrong, basically for long-run energy balance reasons.
I’m not saying anything else about the structure of the causal graphs, which could be arbitrarily complicated and involve arbitrarily many nodes and dependencies. I’m just saying that if you apply the do operator on calorie intake and raise it by 20% then you’d get an increase in mean body mass that’s about as big as what we’ve seen.
Thanks for clarifying that I misrepresented your view. Based on your response here, you’re pointing out that there’s a strong correlation between increased caloric intake at the population level, and increased obesity. You are also saying that the explanations you’ve read from SMTM for why this correlation exists seem wrong, and also that they underestimate the magnitude or importance of the caloric intake.
WRT Eliezer’s arguments, you seem to be agreeing that there may be some underlying force(s) causing that increased caloric intake. However, you are very uncertain about which, if any, of the hypothesized forces(s) are the true causes of increased caloric intake.
Eliezer and others seem to be perhaps mistakenly interpreting you as denying the existence of, or “need for,” a deeper explanation for increased caloric intake and consequent weight gain. You are confused about why they are making this mistake.
I’m not sure who is “to blame” for the miscommunication but I suspect I simply was not clear enough in my top comment. Now it’s likely too late to clear up the issue for most readers as they won’t be following the developments in this thread.
I’m just saying that if you apply the do operator on calorie intake and raise it by 20% then you’d get an increase in mean body mass that’s about as big as what we’ve seen.
This is “assuming there’s no link “increased calorie intake → increased energy expenditure”″, right? I think one of the things Eliezer is saying is that there seems to have been such a link in the past and now there isn’t / it’s much weaker.
That’s not quite true—there is at least the naive link that a higher equilibrium body mass leads you to expend more energy in daily activities even if you exercise the same amount as before. In my very naive model I assume these are directly proportional, but Natalia cites some better research that does a log-linear regression of calorie expenditure on equilibrium (I think? I didn’t check this part) body mass which seems to be more accurate empirically.
I think it’s unclear whether we had the link you mention in the past, too. We definitely had a correlational link: people who did hard labor and ended up exercising a lot every day took in much more calories, as we would expect, and they were generally not obese. However, I think my argument would work just as well in the past if you just applied the do operator on calorie intake per day and looked at the causal impact on equilibrium body mass, as I don’t think there’s evidence that there’s a big downstream link from calorie intake per day to exercise.
I don’t understand why you’re “retrying”. I already agree with your point and you not saying “yes, you already agree with me” is quite confusing to me. As I say in my comment:
Externally, why people feel the need to keep eating until they become obese is not a question with a clear (to me) answer. It could be because there is some process that’s operating in the body that’s taking priority over other activities and hoarding a lot of the energy intake to produce fat cells, which I think is your story.
Do you think this characterization of your position is unfair or wrong? If so, why?
As far as I can see the only object-level point I disagree with you about is that I don’t think the evidence for obesity being like cancer or pregnancy is as strong as you seem to think it is. It’s definitely possible for it to be like that but I would bet against it at even odds. I explain this here:
I don’t think the overfeeding experiments provide strong evidence for your scenario, though I agree that they should be a Bayesian update in favor of accounts in that broad neighborhood. What would convince me is experiments which involve smaller increases in calorie intake but sustained over much longer periods of time, on the order of a year or so. If such experiments failed to find an effect that would be a strong update for me towards your view. Right now I buy the cancer analogy on conceptual grounds but I don’t think we have enough evidence to conclude obesity is like cancer in this regard, though it very well could be the case.
On top of that I also have a separate disagreement with you about emphasis in the context of my comment, since the point of my top comment is to draw attention to 400 kcal/day not being a small increase in calorie intake. You agree with me about this but you just don’t think it’s worth focusing on, probably because you think it’s a trivial observation. I still think it’s something that should be corrected given that SMTM explicitly said that it’s a small increase.
As far as I can see the only object-level point I disagree with you about is that I don’t think the evidence for obesity being like cancer or pregnancy is as strong as you seem to think it is.
Some people certainly are obese because of literal cancer and literal pregnancy. We seem to have strong evidence for that.
The interesting question is about how much of the obesity pandemic is explainable by such factors and not whether evidence for such factors exists.
We certainly don’t see enough pregnancy and cancer to explain the obesity epidemic but there might be other factors that are similar but harder to see. Thermodynamic arguments don’t help us rule out other effects that are similar to pregnancy/cancer.
I agree with everything you said, so again I’m confused why you thought you should make this comment.
I feel like I don’t really disagree with most of the commenters but they either think I do disagree with them or that I did a very bad job of communicating exactly what my point was. It’s hard for me to understand.
I still stand by this claim, again with the caveat that you take it as a correlational use of the word “explain” (which is not at all uncommon e.g. when talking about “fraction of explained variance” and so forth) and not one that suggests a causal explanation of the form “people wanted to eat more food, so they ate more food, so they got fatter as a result”.
Ok. My main point is just to clarify that other people are reading you as talking about explanation in general, not just strictly correlational explanation (if that’s what’s happening).
I do also think that’s not a great use of the word “explain” and “mystery”, because it’s not why the colloquial word is useful. The colloquial words “explain”/”mystery” are useful because they index “more information and ideas given/needed about this”. So just because X correlationally explains Y, and X is true, doesn’t mean there’s no mystery about Y.
I never said there’s no mystery about Y, just that there’s no mystery about Y being true conditional on X being true.
It’s a fair point that my usage of “explain” and “mystery” confused some people but I’m not too sure how else I would have made my point. Should I have said “people today are eating about as much more compared to the past as we would expect given how much fatter they’ve gotten”?
Retrying again:
By the same reasoning:
“Pregnancy” probably isn’t a thing. “Pregnant” people eat around 500 more calories per day. This is sufficient to explain all the weight gain from “pregnancy” without supposing anything other than thermodynamics at work—anyone who eats an extra 500 calories per day will probably gain that much weight over the course of 40 weeks.
I think Ege’s alleging that SMTM presented two causal graphs:
calories → ? → weight gain
calories → weight gain
Ege’s saying that 2 is simpler and sufficient, so we don’t need to posit a ? in the middle.
You’re pointing out that we still need to address a third causal graph:
? → calories → weight gain
Edit: And maybe that there’s also a scenario where ?, calorie intake, and weight gain are all in some complex interrelationship. Maybe contaminants cause more fat deposition and less energy and more hunger, thereby increasing weight gain per calorie, increased calorie intake, and increased contaminant intake via food. Or something.
Ege’s agreeing with you, but wants to emphasize that this is compatible with criticism of SMTM’s alleged emphasis on graph 1.
Note: I say “alleged” only because I’m sidestepping evaluating the truth of Ege’s claim. Just trying to clarify what it is (AFAICT).
I don’t agree with this presentation of what I’m saying.
I’m not terribly sure what SMTM means when they say “the increase in calorie intake is small”, but all possible interpretations of their claim seem wrong. For instance, one plausible interpretation in causal graph lingo is “if you applied the do operator on calorie intake and raised it by 20%, we would have seen an increase in body mass that’s significantly smaller than what we’ve actually seen”. I think this claim is wrong, basically for long-run energy balance reasons.
I’m not saying anything else about the structure of the causal graphs, which could be arbitrarily complicated and involve arbitrarily many nodes and dependencies. I’m just saying that if you apply the do operator on calorie intake and raise it by 20% then you’d get an increase in mean body mass that’s about as big as what we’ve seen.
Thanks for clarifying that I misrepresented your view. Based on your response here, you’re pointing out that there’s a strong correlation between increased caloric intake at the population level, and increased obesity. You are also saying that the explanations you’ve read from SMTM for why this correlation exists seem wrong, and also that they underestimate the magnitude or importance of the caloric intake.
WRT Eliezer’s arguments, you seem to be agreeing that there may be some underlying force(s) causing that increased caloric intake. However, you are very uncertain about which, if any, of the hypothesized forces(s) are the true causes of increased caloric intake.
Eliezer and others seem to be perhaps mistakenly interpreting you as denying the existence of, or “need for,” a deeper explanation for increased caloric intake and consequent weight gain. You are confused about why they are making this mistake.
Is that a more accurate account of your position?
Yes, this summary is accurate.
I’m not sure who is “to blame” for the miscommunication but I suspect I simply was not clear enough in my top comment. Now it’s likely too late to clear up the issue for most readers as they won’t be following the developments in this thread.
Feel free to adapt, or copy/paste, the summary into your parent comment if you like.
This is “assuming there’s no link “increased calorie intake → increased energy expenditure”″, right? I think one of the things Eliezer is saying is that there seems to have been such a link in the past and now there isn’t / it’s much weaker.
That’s not quite true—there is at least the naive link that a higher equilibrium body mass leads you to expend more energy in daily activities even if you exercise the same amount as before. In my very naive model I assume these are directly proportional, but Natalia cites some better research that does a log-linear regression of calorie expenditure on equilibrium (I think? I didn’t check this part) body mass which seems to be more accurate empirically.
I think it’s unclear whether we had the link you mention in the past, too. We definitely had a correlational link: people who did hard labor and ended up exercising a lot every day took in much more calories, as we would expect, and they were generally not obese. However, I think my argument would work just as well in the past if you just applied the do operator on calorie intake per day and looked at the causal impact on equilibrium body mass, as I don’t think there’s evidence that there’s a big downstream link from calorie intake per day to exercise.
You left out weight gain->calories, as in the pregnancy example, and calories ← X → weight gain.
I don’t understand why you’re “retrying”. I already agree with your point and you not saying “yes, you already agree with me” is quite confusing to me. As I say in my comment:
Do you think this characterization of your position is unfair or wrong? If so, why?
As far as I can see the only object-level point I disagree with you about is that I don’t think the evidence for obesity being like cancer or pregnancy is as strong as you seem to think it is. It’s definitely possible for it to be like that but I would bet against it at even odds. I explain this here:
On top of that I also have a separate disagreement with you about emphasis in the context of my comment, since the point of my top comment is to draw attention to 400 kcal/day not being a small increase in calorie intake. You agree with me about this but you just don’t think it’s worth focusing on, probably because you think it’s a trivial observation. I still think it’s something that should be corrected given that SMTM explicitly said that it’s a small increase.
Some people certainly are obese because of literal cancer and literal pregnancy. We seem to have strong evidence for that.
The interesting question is about how much of the obesity pandemic is explainable by such factors and not whether evidence for such factors exists.
We certainly don’t see enough pregnancy and cancer to explain the obesity epidemic but there might be other factors that are similar but harder to see. Thermodynamic arguments don’t help us rule out other effects that are similar to pregnancy/cancer.
I agree with everything you said, so again I’m confused why you thought you should make this comment.
I feel like I don’t really disagree with most of the commenters but they either think I do disagree with them or that I did a very bad job of communicating exactly what my point was. It’s hard for me to understand.
(The thread continues to look to me like what I described here https://www.lesswrong.com/posts/7iAABhWpcGeP5e6SB/it-s-probably-not-lithium?commentId=NxzEfuyGfuao25mrx
i.e. Yudkowsky is responding to the part of your original comment where you said
)
I still stand by this claim, again with the caveat that you take it as a correlational use of the word “explain” (which is not at all uncommon e.g. when talking about “fraction of explained variance” and so forth) and not one that suggests a causal explanation of the form “people wanted to eat more food, so they ate more food, so they got fatter as a result”.
Ok. My main point is just to clarify that other people are reading you as talking about explanation in general, not just strictly correlational explanation (if that’s what’s happening).
I do also think that’s not a great use of the word “explain” and “mystery”, because it’s not why the colloquial word is useful. The colloquial words “explain”/”mystery” are useful because they index “more information and ideas given/needed about this”. So just because X correlationally explains Y, and X is true, doesn’t mean there’s no mystery about Y.
I never said there’s no mystery about Y, just that there’s no mystery about Y being true conditional on X being true.
It’s a fair point that my usage of “explain” and “mystery” confused some people but I’m not too sure how else I would have made my point. Should I have said “people today are eating about as much more compared to the past as we would expect given how much fatter they’ve gotten”?
That’s clearer to me, yeah. It’s unambiguous that it’s about conditional prediction (“we would expect given”) rather than explanation-in-general.