I am always suspicious of mono-factorial explanations of any complex phenomenon, whether it be obesity or climate change. Yet for any such phenomenon there seems to be a population of people, call them philosophical monists, who stridently insist that the sole explanation for A must be B and B alone, and that anyone who claims otherwise or cites contrary evidence is in the pocket of Big B.
Climate change is a funny example here! It seems like there's a pretty strong consensus that a single factor (CO2 emissions) causes the large majority of warming. And I'm unaware of any hardcore faction of 100% carbonists who deny the role of methane.
I guess my wider claim is that monocausal explanations are often "right enough", if you see what I mean. Tobacco didn't turn out to cause 100% of lung cancer, but it did cause 90-95% - that was a huge surprise, and a stupendously important public health victory. I don't think it's likely that there's a nearly-monocausal explanation of the obesity epidemic, but I do think it's plausible, and good on the seed oil guys, plus Slime Mold Time Mold etc, for trying to find it.
I think it’s important to distinguish between processed foods and *highly* processed foods. Even hunter gatherers used fire to cook meat to make it easier to chew and digest. Potatoes would kill you if eaten raw, so we cook them in all kinds of ways to make them safe, edible, and (most importantly) delicious. Avoiding foods that are processed in any way is basically a raw food diet, and I don’t think there’s any conclusive evidence that this is optimal for human health. Hunter gatherers were certainly lean, but they also very likely suffered long periods of nutrient scarcity, which (probably) took a toll on their lifespans. That said, I try to be mindful of my vegetable oil consumption and prefer to use less “processed” alternatives as often as I can. My wife’s fried chicken is just too damn good to pass up.
Totally agree—processing is a spectrum, and I personally have no plans to give up cooked food! (What happened to that old theory that cooking was the core technology that made humans become humans?)
You mean the theory that attributes our big brains to the sudden uptick in surplus calories as a direct result of cooking? That's a pet favorite of mine, although I'm sure the whole story is more complicated than that.
Great write-up! Now, can you do a follow-up on the "ultra processed food" craze?
This sounds like the latest and greatest nutrition ultra-mega-boogeyman.
In other words, is "ultra processed" really just a shortcut for "eat better qualify food"? Or is it really, truly about the "ultra processing?" (I suspect the former)
Drilling down a bit more, I'm curious about the dynamics of processed meats. Yes, there are damning studies. Yes, nitrates seem not good. But one can get no-nitrate processed meats. Is that OK? But, no, they're heavily salted! That's bad, right? But, wait! New views on existing studies appear to indicate that salt (like cholesterol) may be a victim of correlation vs. causation.
The entire field of nutrition seems to be creating/caught up in a bit of a crisis.
I understand being suspicious of all the criticism from experts of "processed" food. It sounds like a very vague boogeyman, an extremely broad category of mostly-unrelated things that also mostly seem unlikely to be harmful (chopping?). I have heard many people make this argument, and indeed I used to believe it myself! But these days I do tend to accept the conventional wisdom that avoiding "ultra-processed" food is the single best diet advice we have. My argument for this is somewhat complicated (so maybe I should write a post on it) but it's ultimately an argument that nutrition is too complex and uncertain for it to be productive for us to try to reason about at the level of nitrates and salt and specific fatty-acids.
Knowing the drivers of nutrition health will enable consumers to better demand the changes that need to be made in order for food makers to make better food products.
Imagine if we found out what the real culprit of cancer is in deli meats, and this became mainstream knowledge. The deli meat industry would then be compelled to create better product (even if it ends up still not being a *good* product). I mean, someone at Boar's Head thinks that nitrates are the problem, so they already offer nitrate-free products! I view this as evidence that this dynamic works.
This seems like a better outcome than fantasizing that people will actually stop buying deli meats.
Oh sure, we should definitely continue to try to understand the mechanisms. I guess as we gradually gain more understanding we should shift from using very high level heuristics (like "no processed food") to more low-level reasoning. My feeling is that it's still wisest stay close to the high level heuristics end of the spectrum. But not always! For example, I think it's wise to specifically avoid trans fat (even though we don't understand how trans fats cause most of the problems they cause).
Unfortunately, more information does not automatically translate into more knowledgeable consumers. My understanding is that activists tend to be either ignorant or systematically misinformed when compared with high-information individuals who participate in the sort of dispassionate truth-seeking we commonly envision, who aren't nearly as inclined to advocacy.
I'm not sure what the truth is, nor that it always wins. There's also the matter of the incalculable collateral damage that arises as a matter of course from well-meaning advocacy. My mother has been shopping organic for years, and I guarantee you that the 500% upcharge has done more harm in her life, financially, than whatever infinitesimal advantage free-range eggs might've bought her.
> My argument for this is somewhat complicated (so maybe I should write a post on it) but it's ultimately an argument that nutrition is too complex and uncertain for it to be productive for us to try to reason about at the level of nitrates and salt and specific fatty-acids.
Agree, but I think the main operating force here is economic incentives, not knowledge. Even if we slowly get insight into the effect of individual components, ultra-processing still gives a huge amount of power to these macro-companies to optimize for their own aims which are largely orthogonal to our long-term health. So best avoided anyway!
I would recommend you the book Ultra-Processed People if you're curious.
I think "eat better quality food" is meaningless, what exactly is it that makes food low quality and how or why is it bad?
The fundamental argument in the book seems to be that ultra processed foods are made by dissolving the raw ingredients, such as corn or soy, and putting them back together at the molecular level into molecules your body has never seen before. This is a much more compelling explanation of why ultra-processing is indeed bad, while cutting, salting and cooking is not. In that regard, ultra processing strikes me as a bad word, and it should really be called something like chemically constructed food-like substances.
I appreciate this. I, too, have recently gone down a seed oil rabbit hole. There's a lot of enthusiasm and a lot of (very motivating) good results, but the causal factors remain quite unclear.
From Hannah Rithcie's Most Excellent "Not the End of the World"
Researchers at Harvard University have loudly pushed against this backlash. A meta-analysis covering 30 studies found that omega-6s lowered the risk of heart disease: those with more in their bloodstream were 7% less likely to develop
Another study followed around 2,500 men for an average of 22 years, and found that those with the highest blood levels of omega-6s had a much lower risk of dying from any disease. Studies show that they lower cholesterol and blood sugar. And the American Heart Foundation found that getting 5% to 10% of your calories from omega-6s reduces your risk of heart disease.
I've been following this debate for some time and I've landed in a similar place. My bird's eye takeaway for dietary wisdom has slowly coalesced into something like a smattering of loosely-related Rule of Thumb heuristics:
1. Don't drink your calories; instead, drink almost exclusively water
2. Eat mostly ingredients; avoid foodstuff with inscrutable origins
3. Refined carbohydrates, sugar and trans fats are on the naughty list
4. Err on the side of low-carb, err towards higher protein consumption
5. Don't eat gluten if you've got IBD (or any of the associated/adjacent conditions)
6. Prebiotic, soluble fiber might be good for you, but most fiber probably isn't
I grew up in a household that demonized mainstream medicine and lionized Dr. Oz, and since then I've had to eat a lot of crow as my personal investigations have overturned my previously unexamined beliefs, handed down by my parents; such subjects as iodized salt, fluoride in toothpaste and tap water, psyllium husk as a dietary supplement, colloidal silver and other homeopathic remedies that my mother/grandmother used to proselytize.
Probably the most contentious of the numbered list above are numbers five and six, both of which should be considered /strong opinions held loosely/ because they are based mostly on personal anecdote. I've had gastrointestinal issues since I was born, but I wasn't given an official diagnosis of IBD 'til well into high school, and it took them another decade to upgrade that diagnosis to full-blown Ulcerative Colitis. I've been through several phases of wacky self-experimentation, but my condition has been perfectly under control for the past five years now. And this is AFTER it had gotten so bad that I was pretty sure I'd be facing down a colectomy. The things that had the most tangible impact were FMTs (mostly this was a one-and-done sorta deal), cutting gluten completely out of my diet (I have since reintroduced gluten in very small, occasional amounts and it no longer triggers immediate adverse affects although it's still not pleasant) and avoiding fiber almost entirely.
Staying inquisitive, skeptical and genuinely oriented towards the truth has made all the difference. The heuristics that I listed above could be inverted if I discovered strong enough evidence, although the overall trajectory of my gut health has weighted my priors down pretty heavily in some regards. You've done an unusually good job capturing just how difficult it is thinking about diet, since it's almost impossible to have anything resembling a complete picture. I've tried to keep the odds of harm/benefit on the correct sides of the Pareto Principle where my takeaways are concerned, but quite likely I'm just plain wrong about something.
Congrats for getting out of your inherited dogma, that's always hard work but rewarding.
Largely agree with your list but I"m not so sure on #4, my vague impression is that the demonization of carbs in favor of protein may be just another fad.
I think you've debunked it well enough. If you need to look TOO hard, you'll find what you're looking for because you get sloppy (as shown by your GDP data). The correlation that is easier to see is with "highly processed foods," meaning vending machine stuff, packaged muffins, that sort of thing. Obesity skyrocketed in Mexico after NAFTA made it possible to import said junk food in large, inexpensive quantities. I'll add this separate point: palm oil use is decimating jungles in Indonesia and other places, where jungles are being cut down for palm plantations. So... choose your (or the Earth's) poison.
Nice write-up. What is your source for the linoleic acid % in body composition over time? That's a very striking graph, but I'd like to know the source/methodology.
I have done a deeper dive on this than I care to admit, and where I landed was:
1. Olive oil and avocado oil are your best bet for everyday use in most applications.
2. Animal fats are okay *in moderation*. Don't go crazy. Avoid the non-animal highly saturated fats like coconut oil and palm oil.
3. Try to get some omega-3s. They are preferentially processed as compared to omega-6s, and the metabolic channel doesn't have infinite capacity. If you are processing omega-3s, you aren't processing omega-6s.
4. Avoid seed oils to the extent possible. But there's no need to be a zealot. Have some chips and queso when you're at the Mexican restaurant. It will be okay. There isn't a really good reason to believe that low level PUFA intake results in increased risks.
In practical terms, the regimen above is fairly conventional advice on diet (avoid junk food and eat lean proteins and vegetables and olive oil...Who knew??), and the downside risks seem to be slim to none.
My working theory is, more or less, PUFA intake above a certain threshold can interact with other diet and lifestyle factors to result in metabolic dysfunction that can cascade in lots of negative directions. It's tough to evaluate it all because, from an empirical perspective, the systems are absurdly complex and multi-variate and also because the impact of the hypothesized metabolic dysfunction is more in the way of long term chronic issues (diabetes, obesity, increased inflammation / cancer, etc.), whereas the benefits of replacing bad saturated fats with PUFAs is in the form of acute harm reduction (avoiding strokes, heart attacks, etc.).
Just to add to that. The main point the author there makes is that linoleic acid itself doesn’t necessarily make you fat. But it triggers torpor in animals to trigger pathways to start accumulating fat. It’s like a trigger from nature. Because usually linoleic acid rich foods are available around fall which is when animals need to store weight before the winter.
The origin of schools of thought like the seed oil one are pretty fascinating. Like why did people skip by the more straightforward stuff like calories in and out, glycemic index, highly palatable food, and nutrients? I mean, I guess I know the answer - it's because the basic answers are kind of boring and it's much more fun to have access to special knowledge that makes you special and also presents a workaround to boring stuff like eating less. And sometimes the special knowledge turns out to be true.
Overall, I guess I'm glad that we have people going off on weird tangents like seed oils, lithium in the water, and potato diets, but most of the time they're going to come to nothing. They're very low probability, high payoff bets.
I also continue to be amazed by how hard it is to really know anything in epidemiology. We've done, what, 30/50/100 studies on seed oils? And the answer we come out with after careful consideration for what seed oils do is, "Hmm, not quite sure, probably nothing in particular." I guess that's just how it is, but sometimes it makes me laugh/cry.
One reason why calories in/calories out has come into question is because aggregate food supply data show that calories per person have flattened, yet obesity continues to rise in an unmitigated fashion.
Similarly, sugar supply has tanked over the past 20 years while obesity has climbed.
To me the bigger mystery is why there is so much geographical variation *within* countries. Calories can’t explain that, neither can seed oils (probably).
Do you have a source that calories/person have flattened? I just checked the FAO data (where most people seem to get these numbers: https://www.fao.org/faostat/en/#data/FBS) and here's what they have for kcal/cap/d for the US in the last few years:
2010: 3729
2011: 3727
2012: 3765
2013: 3754
2014: 3742
2015: 3754
2016: 3777
2017: 3791
2018: 3824
2019: 3876
2020: 3892
2021: 3911
Pretty noisy, but looks like it's rising overall. But then... I guess this is only for calories "delivered" to people not necessarily consumed. (I can't believe people are actually consuming 3900 kcal/day on everage!)
Yes, I go to two sources: FAO [via "Our World In Data"] and the USDA Economic Research Service. I only had FAO up to 2017 so I didn't know of the recent uptick since then.
For the USDA ERS, it unfortunately cuts out at 2010 but here's what it reports:
2001: 2,546
2002: 2,574
2003: 2,566
2004: 2,566
2005: 2,551
2006: 2,554
2007: 2,562
2008: 2,543
2009: 2,469
2010: 2,501
I'm not sure why it's off by over 1,000 calories from the FAO data.
You can also get food diary data from NHANES. These show a completely flat trajectory since 2000 but not sure they are believable since it's self-reported food diary data, so easy to "forget" that you ate that extra handful of M&M's.
Unfortunately you have to click through and open each year's PDF to look at the data. I have an R script that goes through it and creates a chart that I'd be happy to share with you if you'd like.
Interestingly the food diary data shows an uptick of omega-6 PUFA consumption along with an uptick in the total disappearance of edible seed oils from the food supply data, but the levels are *way* off across the two.
The story gets even more interesting if you go back further. If you look at data from before 1960 (which is admittedly hard to come by), you'll find that we ate a lot more in, say, 1930 than we do today.
Wait, does it show that? That link shows that men in the heaviest labor roles were eating 3900 calories per day, and men in light labor roles much less. But the data above for 2021 suggests that the average over the *whole population* (women, children, men who are mostly not in heavy labor roles) was 3900.
Great post, but isn’t using BMI for global comparisons problematic due to between-race variance in how well it correlates with obesity/bad health outcomes?
On the wider and more interesting question of "what went wrong", I agree that singe-cause explanations are not very believable. But in very broad terms, in the last century or so humanity has been hyper-optimizing all sorts of things. From capital usage, competition and advertising, to land yields and fabrication recipes, everything is now hyper optimized, or it just can't compete in the mainstream. Not to idealize or simplify the past too much, but nothing used to be so relentlessly optimized. Cultures would vary from one place to the next instead of being all in contact and competition, innovation was slow, expectations were much lower, and there weren't just that many people around to be fed and sold to.
And what happens in a dynamic system when you optimize for a subset of parameters, is that the *rest* of the parameters just jump around randomly. If there was some kind of cultural selection pressure keeping them within some bounds, it gets overwhelmed and is no longer operative.
So I'm not surprised that the result is what some people nowadays call a "polycrisis". Everything that isn't being directly optimized for by the economic system is just slowly going out of whack, from the Earth's climate to our physical and mental health, to the sanity of cultural output. It's Cory Doctorow's enshitiffication, but on the broadest scale.
And on the practical terms of "what can I do with the moderate amount of effort that I'm willing to put on this", I basically agree with Dynomight and other commenters' suggestions. At home we just use cold-pressed olive oil for everything; it's not some hard won virtue over here in Spain, it's just what my parents and their parents used to do, we're lucky the this particular continuity didn't get broken. Drink mostly water or teas (herbal or regular), eat plenty of vegetables, etc. And for home usage I try to avoid stuff with ingredients someone's great grandma wouldn't recognize - we get enough of that shit when eating out.
(accidental duplicate comment removed)
Thank you for that excellent analysis.
I am always suspicious of mono-factorial explanations of any complex phenomenon, whether it be obesity or climate change. Yet for any such phenomenon there seems to be a population of people, call them philosophical monists, who stridently insist that the sole explanation for A must be B and B alone, and that anyone who claims otherwise or cites contrary evidence is in the pocket of Big B.
The term I've heard for those people is "hedgehog": https://en.wikipedia.org/wiki/The_Hedgehog_and_the_Fox
Climate change is a funny example here! It seems like there's a pretty strong consensus that a single factor (CO2 emissions) causes the large majority of warming. And I'm unaware of any hardcore faction of 100% carbonists who deny the role of methane.
I guess my wider claim is that monocausal explanations are often "right enough", if you see what I mean. Tobacco didn't turn out to cause 100% of lung cancer, but it did cause 90-95% - that was a huge surprise, and a stupendously important public health victory. I don't think it's likely that there's a nearly-monocausal explanation of the obesity epidemic, but I do think it's plausible, and good on the seed oil guys, plus Slime Mold Time Mold etc, for trying to find it.
this is cool and interesting! thank you.
I think it’s important to distinguish between processed foods and *highly* processed foods. Even hunter gatherers used fire to cook meat to make it easier to chew and digest. Potatoes would kill you if eaten raw, so we cook them in all kinds of ways to make them safe, edible, and (most importantly) delicious. Avoiding foods that are processed in any way is basically a raw food diet, and I don’t think there’s any conclusive evidence that this is optimal for human health. Hunter gatherers were certainly lean, but they also very likely suffered long periods of nutrient scarcity, which (probably) took a toll on their lifespans. That said, I try to be mindful of my vegetable oil consumption and prefer to use less “processed” alternatives as often as I can. My wife’s fried chicken is just too damn good to pass up.
Totally agree—processing is a spectrum, and I personally have no plans to give up cooked food! (What happened to that old theory that cooking was the core technology that made humans become humans?)
You mean the theory that attributes our big brains to the sudden uptick in surplus calories as a direct result of cooking? That's a pet favorite of mine, although I'm sure the whole story is more complicated than that.
Great write-up! Now, can you do a follow-up on the "ultra processed food" craze?
This sounds like the latest and greatest nutrition ultra-mega-boogeyman.
In other words, is "ultra processed" really just a shortcut for "eat better qualify food"? Or is it really, truly about the "ultra processing?" (I suspect the former)
Drilling down a bit more, I'm curious about the dynamics of processed meats. Yes, there are damning studies. Yes, nitrates seem not good. But one can get no-nitrate processed meats. Is that OK? But, no, they're heavily salted! That's bad, right? But, wait! New views on existing studies appear to indicate that salt (like cholesterol) may be a victim of correlation vs. causation.
The entire field of nutrition seems to be creating/caught up in a bit of a crisis.
I understand being suspicious of all the criticism from experts of "processed" food. It sounds like a very vague boogeyman, an extremely broad category of mostly-unrelated things that also mostly seem unlikely to be harmful (chopping?). I have heard many people make this argument, and indeed I used to believe it myself! But these days I do tend to accept the conventional wisdom that avoiding "ultra-processed" food is the single best diet advice we have. My argument for this is somewhat complicated (so maybe I should write a post on it) but it's ultimately an argument that nutrition is too complex and uncertain for it to be productive for us to try to reason about at the level of nitrates and salt and specific fatty-acids.
Yes but!
Knowing the drivers of nutrition health will enable consumers to better demand the changes that need to be made in order for food makers to make better food products.
Imagine if we found out what the real culprit of cancer is in deli meats, and this became mainstream knowledge. The deli meat industry would then be compelled to create better product (even if it ends up still not being a *good* product). I mean, someone at Boar's Head thinks that nitrates are the problem, so they already offer nitrate-free products! I view this as evidence that this dynamic works.
This seems like a better outcome than fantasizing that people will actually stop buying deli meats.
Oh sure, we should definitely continue to try to understand the mechanisms. I guess as we gradually gain more understanding we should shift from using very high level heuristics (like "no processed food") to more low-level reasoning. My feeling is that it's still wisest stay close to the high level heuristics end of the spectrum. But not always! For example, I think it's wise to specifically avoid trans fat (even though we don't understand how trans fats cause most of the problems they cause).
Unfortunately, more information does not automatically translate into more knowledgeable consumers. My understanding is that activists tend to be either ignorant or systematically misinformed when compared with high-information individuals who participate in the sort of dispassionate truth-seeking we commonly envision, who aren't nearly as inclined to advocacy.
I'm not sure what the truth is, nor that it always wins. There's also the matter of the incalculable collateral damage that arises as a matter of course from well-meaning advocacy. My mother has been shopping organic for years, and I guarantee you that the 500% upcharge has done more harm in her life, financially, than whatever infinitesimal advantage free-range eggs might've bought her.
> My argument for this is somewhat complicated (so maybe I should write a post on it) but it's ultimately an argument that nutrition is too complex and uncertain for it to be productive for us to try to reason about at the level of nitrates and salt and specific fatty-acids.
Agree, but I think the main operating force here is economic incentives, not knowledge. Even if we slowly get insight into the effect of individual components, ultra-processing still gives a huge amount of power to these macro-companies to optimize for their own aims which are largely orthogonal to our long-term health. So best avoided anyway!
I would recommend you the book Ultra-Processed People if you're curious.
I think "eat better quality food" is meaningless, what exactly is it that makes food low quality and how or why is it bad?
The fundamental argument in the book seems to be that ultra processed foods are made by dissolving the raw ingredients, such as corn or soy, and putting them back together at the molecular level into molecules your body has never seen before. This is a much more compelling explanation of why ultra-processing is indeed bad, while cutting, salting and cooking is not. In that regard, ultra processing strikes me as a bad word, and it should really be called something like chemically constructed food-like substances.
I appreciate this. I, too, have recently gone down a seed oil rabbit hole. There's a lot of enthusiasm and a lot of (very motivating) good results, but the causal factors remain quite unclear.
TY for this, especially the Distraction part.
From Hannah Rithcie's Most Excellent "Not the End of the World"
Researchers at Harvard University have loudly pushed against this backlash. A meta-analysis covering 30 studies found that omega-6s lowered the risk of heart disease: those with more in their bloodstream were 7% less likely to develop
Another study followed around 2,500 men for an average of 22 years, and found that those with the highest blood levels of omega-6s had a much lower risk of dying from any disease. Studies show that they lower cholesterol and blood sugar. And the American Heart Foundation found that getting 5% to 10% of your calories from omega-6s reduces your risk of heart disease.
I've been following this debate for some time and I've landed in a similar place. My bird's eye takeaway for dietary wisdom has slowly coalesced into something like a smattering of loosely-related Rule of Thumb heuristics:
1. Don't drink your calories; instead, drink almost exclusively water
2. Eat mostly ingredients; avoid foodstuff with inscrutable origins
3. Refined carbohydrates, sugar and trans fats are on the naughty list
4. Err on the side of low-carb, err towards higher protein consumption
5. Don't eat gluten if you've got IBD (or any of the associated/adjacent conditions)
6. Prebiotic, soluble fiber might be good for you, but most fiber probably isn't
I grew up in a household that demonized mainstream medicine and lionized Dr. Oz, and since then I've had to eat a lot of crow as my personal investigations have overturned my previously unexamined beliefs, handed down by my parents; such subjects as iodized salt, fluoride in toothpaste and tap water, psyllium husk as a dietary supplement, colloidal silver and other homeopathic remedies that my mother/grandmother used to proselytize.
Probably the most contentious of the numbered list above are numbers five and six, both of which should be considered /strong opinions held loosely/ because they are based mostly on personal anecdote. I've had gastrointestinal issues since I was born, but I wasn't given an official diagnosis of IBD 'til well into high school, and it took them another decade to upgrade that diagnosis to full-blown Ulcerative Colitis. I've been through several phases of wacky self-experimentation, but my condition has been perfectly under control for the past five years now. And this is AFTER it had gotten so bad that I was pretty sure I'd be facing down a colectomy. The things that had the most tangible impact were FMTs (mostly this was a one-and-done sorta deal), cutting gluten completely out of my diet (I have since reintroduced gluten in very small, occasional amounts and it no longer triggers immediate adverse affects although it's still not pleasant) and avoiding fiber almost entirely.
Staying inquisitive, skeptical and genuinely oriented towards the truth has made all the difference. The heuristics that I listed above could be inverted if I discovered strong enough evidence, although the overall trajectory of my gut health has weighted my priors down pretty heavily in some regards. You've done an unusually good job capturing just how difficult it is thinking about diet, since it's almost impossible to have anything resembling a complete picture. I've tried to keep the odds of harm/benefit on the correct sides of the Pareto Principle where my takeaways are concerned, but quite likely I'm just plain wrong about something.
Thanks for another solid article, Dynomight.
Congrats for getting out of your inherited dogma, that's always hard work but rewarding.
Largely agree with your list but I"m not so sure on #4, my vague impression is that the demonization of carbs in favor of protein may be just another fad.
I think you've debunked it well enough. If you need to look TOO hard, you'll find what you're looking for because you get sloppy (as shown by your GDP data). The correlation that is easier to see is with "highly processed foods," meaning vending machine stuff, packaged muffins, that sort of thing. Obesity skyrocketed in Mexico after NAFTA made it possible to import said junk food in large, inexpensive quantities. I'll add this separate point: palm oil use is decimating jungles in Indonesia and other places, where jungles are being cut down for palm plantations. So... choose your (or the Earth's) poison.
Nice write-up. What is your source for the linoleic acid % in body composition over time? That's a very striking graph, but I'd like to know the source/methodology.
I have done a deeper dive on this than I care to admit, and where I landed was:
1. Olive oil and avocado oil are your best bet for everyday use in most applications.
2. Animal fats are okay *in moderation*. Don't go crazy. Avoid the non-animal highly saturated fats like coconut oil and palm oil.
3. Try to get some omega-3s. They are preferentially processed as compared to omega-6s, and the metabolic channel doesn't have infinite capacity. If you are processing omega-3s, you aren't processing omega-6s.
4. Avoid seed oils to the extent possible. But there's no need to be a zealot. Have some chips and queso when you're at the Mexican restaurant. It will be okay. There isn't a really good reason to believe that low level PUFA intake results in increased risks.
In practical terms, the regimen above is fairly conventional advice on diet (avoid junk food and eat lean proteins and vegetables and olive oil...Who knew??), and the downside risks seem to be slim to none.
My working theory is, more or less, PUFA intake above a certain threshold can interact with other diet and lifestyle factors to result in metabolic dysfunction that can cascade in lots of negative directions. It's tough to evaluate it all because, from an empirical perspective, the systems are absurdly complex and multi-variate and also because the impact of the hypothesized metabolic dysfunction is more in the way of long term chronic issues (diabetes, obesity, increased inflammation / cancer, etc.), whereas the benefits of replacing bad saturated fats with PUFAs is in the form of acute harm reduction (avoiding strokes, heart attacks, etc.).
Have you reviewed the works of Fire in a bottle and the surrounding community? Lots of good meta research on this topic.
Just to add to that. The main point the author there makes is that linoleic acid itself doesn’t necessarily make you fat. But it triggers torpor in animals to trigger pathways to start accumulating fat. It’s like a trigger from nature. Because usually linoleic acid rich foods are available around fall which is when animals need to store weight before the winter.
The origin of schools of thought like the seed oil one are pretty fascinating. Like why did people skip by the more straightforward stuff like calories in and out, glycemic index, highly palatable food, and nutrients? I mean, I guess I know the answer - it's because the basic answers are kind of boring and it's much more fun to have access to special knowledge that makes you special and also presents a workaround to boring stuff like eating less. And sometimes the special knowledge turns out to be true.
Overall, I guess I'm glad that we have people going off on weird tangents like seed oils, lithium in the water, and potato diets, but most of the time they're going to come to nothing. They're very low probability, high payoff bets.
I also continue to be amazed by how hard it is to really know anything in epidemiology. We've done, what, 30/50/100 studies on seed oils? And the answer we come out with after careful consideration for what seed oils do is, "Hmm, not quite sure, probably nothing in particular." I guess that's just how it is, but sometimes it makes me laugh/cry.
One reason why calories in/calories out has come into question is because aggregate food supply data show that calories per person have flattened, yet obesity continues to rise in an unmitigated fashion.
Similarly, sugar supply has tanked over the past 20 years while obesity has climbed.
To me the bigger mystery is why there is so much geographical variation *within* countries. Calories can’t explain that, neither can seed oils (probably).
Do you have a source that calories/person have flattened? I just checked the FAO data (where most people seem to get these numbers: https://www.fao.org/faostat/en/#data/FBS) and here's what they have for kcal/cap/d for the US in the last few years:
2010: 3729
2011: 3727
2012: 3765
2013: 3754
2014: 3742
2015: 3754
2016: 3777
2017: 3791
2018: 3824
2019: 3876
2020: 3892
2021: 3911
Pretty noisy, but looks like it's rising overall. But then... I guess this is only for calories "delivered" to people not necessarily consumed. (I can't believe people are actually consuming 3900 kcal/day on everage!)
Yes, I go to two sources: FAO [via "Our World In Data"] and the USDA Economic Research Service. I only had FAO up to 2017 so I didn't know of the recent uptick since then.
The USDA ERS link is here (go to "Totals" tab): https://view.officeapps.live.com/op/view.aspx?src=https%3A%2F%2Fwww.ers.usda.gov%2Fwebdocs%2FDataFiles%2F50472%2Fcalories.xls%3Fv%3D6095.7&wdOrigin=BROWSELINK
The above link can be accessed by visiting the following link and then clicking on "Calories": https://www.ers.usda.gov/data-products/food-availability-per-capita-data-system/
For the USDA ERS, it unfortunately cuts out at 2010 but here's what it reports:
2001: 2,546
2002: 2,574
2003: 2,566
2004: 2,566
2005: 2,551
2006: 2,554
2007: 2,562
2008: 2,543
2009: 2,469
2010: 2,501
I'm not sure why it's off by over 1,000 calories from the FAO data.
You can also get food diary data from NHANES. These show a completely flat trajectory since 2000 but not sure they are believable since it's self-reported food diary data, so easy to "forget" that you ate that extra handful of M&M's.
The NHANES source is "What We Eat In America" here: https://www.ars.usda.gov/northeast-area/beltsville-md-bhnrc/beltsville-human-nutrition-research-center/food-surveys-research-group/docs/wweia-data-tables/
Unfortunately you have to click through and open each year's PDF to look at the data. I have an R script that goes through it and creates a chart that I'd be happy to share with you if you'd like.
Interestingly the food diary data shows an uptick of omega-6 PUFA consumption along with an uptick in the total disappearance of edible seed oils from the food supply data, but the levels are *way* off across the two.
Thanks. I guess I'll classify this as ambiguous for now.
Which, to be clear, is a shift from my expectations—I would have thought calorie consumption was unambiguously going up!
The story gets even more interesting if you go back further. If you look at data from before 1960 (which is admittedly hard to come by), you'll find that we ate a lot more in, say, 1930 than we do today.
unfashionable.blog/p/obesity
Wait, does it show that? That link shows that men in the heaviest labor roles were eating 3900 calories per day, and men in light labor roles much less. But the data above for 2021 suggests that the average over the *whole population* (women, children, men who are mostly not in heavy labor roles) was 3900.
Here's a document of charts I put together: https://raw.githack.com/tyleransom/obesity-graphs/master/writeup/graphs.pdf
You can find all data + code underlying the document here on GitHub: https://github.com/tyleransom/obesity-graphs
Interesting. I haven't looked into this in detail, but it seems like the FAO had a significant shift in methodology in 2010, might explain the reversal of the trend there? https://fenixservices.fao.org/faostat/static/documents/FBS/Key%20differences%20between%20new%20and%20old%20FBS%20June2022%20.pdf
(But that wouldn't explain the local maxima in 2006...)
Yes, I was vaguely aware of the methodological shift in 2010 but haven't looked too deeply into what it would mean. Thanks for sharing!
Great post, but isn’t using BMI for global comparisons problematic due to between-race variance in how well it correlates with obesity/bad health outcomes?
On the wider and more interesting question of "what went wrong", I agree that singe-cause explanations are not very believable. But in very broad terms, in the last century or so humanity has been hyper-optimizing all sorts of things. From capital usage, competition and advertising, to land yields and fabrication recipes, everything is now hyper optimized, or it just can't compete in the mainstream. Not to idealize or simplify the past too much, but nothing used to be so relentlessly optimized. Cultures would vary from one place to the next instead of being all in contact and competition, innovation was slow, expectations were much lower, and there weren't just that many people around to be fed and sold to.
And what happens in a dynamic system when you optimize for a subset of parameters, is that the *rest* of the parameters just jump around randomly. If there was some kind of cultural selection pressure keeping them within some bounds, it gets overwhelmed and is no longer operative.
So I'm not surprised that the result is what some people nowadays call a "polycrisis". Everything that isn't being directly optimized for by the economic system is just slowly going out of whack, from the Earth's climate to our physical and mental health, to the sanity of cultural output. It's Cory Doctorow's enshitiffication, but on the broadest scale.
And on the practical terms of "what can I do with the moderate amount of effort that I'm willing to put on this", I basically agree with Dynomight and other commenters' suggestions. At home we just use cold-pressed olive oil for everything; it's not some hard won virtue over here in Spain, it's just what my parents and their parents used to do, we're lucky the this particular continuity didn't get broken. Drink mostly water or teas (herbal or regular), eat plenty of vegetables, etc. And for home usage I try to avoid stuff with ingredients someone's great grandma wouldn't recognize - we get enough of that shit when eating out.
Saturated fat has no effect on overall mortality according to the meta
https://sci-hub.se/10.1002/14651858.CD011737.pub3
That meta analysis is discussed at length in the article: https://dynomight.net/seed-oil/#the-inside-view