Debunking food, fat, and fitness myths

[rachelmanija]

I would like your best recs for in-depth articles, studies, or books on the most cutting-edge current knowledge about nutrition, body weight, and health.

I am NOT interested in basic articles about very well-known ideas like fat will kill you, carbs will kill you, meat will kill you, anything your grandma wouldn't recognize as food such as everything but cabbage and turnips will kill you, etc.

I am also NOT interested in articles with a primarily political bent (i.e., "pushing diets on women is based on sexism/capitalism not science;") I agree with that, but I'm looking for stuff where the meat is science and the politics is the side dish rather than the reverse.

I'm looking for more in-depth, up-to-date information on topics including but not limited to...

- Do we actually know anything about nutrition, given the every-five-year swings between "eggs are cardioprotective/eggs are a heart attack on a plate," "fat is the Devil/carbs are the Devil," etc? If so, what is it and how do we know it?

- What is the actual science on grains (and no, I don't mean Wheat Belly)?

- What is the best and most cutting-edge knowledge on gaining strength?

- What is the actual science on the causes of Type 2 diabetes, why its prevalence has risen so much, and its association with obesity?

- What is the actual knowledge of the diet and health of "cavemen?"

- What is the actual science on being fat, thin, and in-between in terms of health? For instance, is it better to be fat and active than "normal weight" and sedentary? (I know the answer but I'm looking for something that goes into this in-depth.)

- What is the deal with "calorie reduction makes you healthier and live longer" vs. "dieting is bad for you?"

I'm already familiar with Michael Pollan, Barbara Ehrenreich, Mark's Daily Apple, Diet Cults, Body of Truth, and The Starvation Experiment. And lots more but those are the things I get recced a lot already.

Comments

[starlady]

This article is from last year and you may have already seen it, but this article by Mark Bittman and David Katz is a pretty good summary of the current state of knowledge about what we actually know about nutrition, to the best of my knowledge: The Last Conversation You'll Ever Need to Have About Eating Right.

[rachelmanija]

Thanks!

[havocthecat]

One of my best friends is getting her PhD in nursing. Let me see if she has any information on this from her classes or from her work experience (she is presently in a hospital setting, but also adores research) and then I can hopefully get back to you.

[rachelmanija]

Thanks, that would be awesome! I have enough of a medical background to read more academic stuff.

[naye]

The University of Cambridge Epidemiology Unit is full of people trying to answer a lot of these questions, but because they're scientists they don't give quick cut-and-dry answers about anything. Their research papers should all be available open access, and they have a Researcher Voices section where they have podcasts, blog posts etc aimed at a general audience.

Disclaimer: I worked there as an admin for years, which is the only reason I know this page exists. I am not a scientist and can't actually parse research papers.

[rachelmanija]

Thanks, that sounds great!

[pameladean]

This is an account of an experiment run on consenting conscientious objectors after World War II, with the purpose of finding out what was the best way to help the millions of people who had been deprived of adequate food during the war. The article compares the deprivation that the subjects underwent to that mandated by weight-loss diets. If I hadn't eschewed dieting forever already, this would certainly have made me do so.

https://www.refinery29.com/en-us/minnesota-starvation-experiment

P.

[rachelmanija]

Thanks!

[sciatrix]

I work on energy balance, metabolism, and leptin, albeit at a jaunty angle from people studying human body weight. Let me see what I can tease out for you. In the meantime, books you might find interesting that you haven't listed are Marlene Zuk's Paleofantasy and Traci Mann's Secrets From the Eating Lab. Mann's book in particular links to one of the most startling findings I've run into in years, which is that the perception of how good a food will taste/how "healthy" it is actually influences how much ghrelin is secreted in response (ghrelin being a hormone associated with being full-not-hungry, much like my leptin).

- What is the actual knowledge of the diet and health of "cavemen?"
If humans can fit it in their mouth and it won't immediately kill them, historically humans have tended to give eating it their best shot.

- Do we actually know anything about nutrition, given the every-five-year swings between "eggs are cardioprotective/eggs are a heart attack on a plate," "fat is the Devil/carbs are the Devil," etc? If so, what is it and how do we know it?
In my personal estimation, having gone digging through a bunch of this literature? We know approximately how much you probably need to keep someone alive, and we know how dietary deficiencies like rickets work. We have a rough idea of the types of diets associated with longevity, but we don't have a good idea of how transferrable those diets are to other people, and we don't really understand well how adiposity (fatness) and diet fit together, nor do we have a great understanding of how these things interact with other things (like STRESS). We know that if you feed mice and rats very high-fat diets, they will become obese, and we know that it's very hard to get people to sustainably change weights outside of about 20lbs away from their "set point". We do not understand how "set points" get set or why they change over time.

- What is the actual science on being fat, thin, and in-between in terms of health? For instance, is it better to be fat and active than "normal weight" and sedentary? (I know the answer but I'm looking for something that goes into this in-depth.)

It's better to be active. If you want it, I'll go digging for the primary literature, but the Mann book also talks a lot more about this in a lot of detail, and I would probably start by looking into her citations.

[sciatrix]

Oh, and before I forget--let me just point out that stress, especially chronic stress, is a huge factor in weight gain, to the point that one of the existing models for obesity in rats is stress-induced hyperphagia. I cannot overestimate how much energy balance and stress are hooked together (as are things like reproductive investment and social context). I would be very interested in looking at overall stress levels in the context of modern weight gain, personally.

In the meantime, I'm looking at the interactions between cortisol and leptin in the context of social behavior, and I'm really excited to see that data once I can successfully analyze it.

[telophase]

This is a few years old, but IIRC, Spark: The Revolutionary New Science of Exercise and the Brain was a good look at what we know about exercise ca. 2008 (1st edition) and 2013 (2nd edition).

[rachelmanija]

Thanks! I've been meaning to read that, so thanks for reminding me.

[shati]

Ancestral Appetites: Food in Prehistory by Kristen Gremillion was published in 2011, so YMMV on cutting edge, but it's one of the newer books I could find on the subject. (Paleofantasy is the other, but I haven't read it yet.) It's mostly focused on how flexible human diets and human behavior around food have been, but there's some discussion of nutrition, and a lot of examples of what's known about pre-Neolithic food in particular areas and how it's known.

[rachelmanija]

Thanks! That sounds fascinating.

[jenett]

She's not currently updating, but the Fat Nutritionist has been a great source for breaking down some of the research and what people misread in the research - she's got an articles and resources section on her site as well as the stuff in her blog posts.

[vass]

That's one of the links I was about to post.

The other one is bigfatscience. The blogger's a scientist (in I think a different field) who runs that Tumblr as a hobby. The FAQ has the tags you'll need to have a hope of navigating it.

[longstrider]

I've enjoyed Healthcare Triage on Youtube hosted by Dr. Aaron Carroll. He takes short looks at health science news that has made headlines and then looks at what the research actually says. Lots of talk about the different ways that statistics don't mean what people think they mean and which ones are likely to be the most relevant. Also how different kinds of research articles can tell us different kids of things. (experiments in animals vs people, review articles, clinical trials etc etc) He also has a book called 'The Bad Food Bible'. While I haven't read it, I generally trust that he's going to tell you exactly why he's said X is likely ok/good for you and link to the research to back it up.

[shopfront]

I quite like The Food Medic, who's a junior doctor in the UK with a specific interest in nutrition. It sounds like you're pretty well informed on the basics already, so she might not deep-dive in the way you're currently looking for though. But she's across a lot of channels (I mostly just use her instagram and podcasts) and so a convenient sort of general ongoing background content choice for me and I often look to see if she's written or spoken on a subject if I hear some new health thing that I want to fact check. I find her a good mix of being super enthusiastic and interested in new research and info, while also really good at keeping things in perspective and very upfront about where there's gaps in current knowledge. Her guests are largely (though not solely) also medical professionals and researchers, so she can sometimes be a good bouncing spot for useful citations or people who do specialise in the actual cutting edge things. Overall I'd say she's very in keeping with The Last Conversation article linked above as being sensible and evidence based and focused on the basics.

Incidentally, she's eating mostly vegan lately - but she's also the first person to interrupt anyone specifically preaching any given diet including veganism and is very open that it's a super personal choice, and that there's loads of diet choices that may be better for some people/there's pros and cons to any diet. So if you're looking for more info in that direction (either for or against) to arm yourself against pushy doctors, she might be helpful there.

[megpie71]

One nobody's mentioned yet is The Angry Chef, who works on debunking a lot of the pseudoscience in food fads.

[rattfan]

Off topic - but thanks for all this. My doc has just told me I need to have more bone strengthening stuff in my diet (which she already made me change last year).

[rydra_wong]

What is the actual knowledge of the diet and health of "cavemen?"

Diet: that hunter-gatherers can and will (and did) eat everything available to them.

No agriculture so no farmed grains (though there's evidence that people did, for example, gather grass seeds if they were available and make porridge) or legumes, no processed seed oils, no cane or beet sugar but honey if/when you can get it, no dairy until you reach the nomadic pastoralist stage (at which point a lot of people evolve lactose tolerance), minimal trans fats because you only get them in significant quantities when humans start industrially processing vegetable fats in the 1950s for things like margarine.

But aside from those things which were literally unavailable: EVERYTHING THAT A HUMAN CAN INGEST THAT HAS CALORIES IN IT AND IS NOT ACTIVELY POISONOUS (OR CAN BE PROCESSED SOMEHOW SO IT'S NOT POISONOUS). IF IT EXISTS HUMANS WILL SHOVE IT IN OUR FACES.

Based on knowledge of existing hunter-gatherer groups (or records of how groups were eating before they collided with "modern"/Western civilization), there's a very wide range of macro-nutrient ratios, depending on whether (for example) the environment provides lots of starchy roots to dig up.

https://www.sciencedirect.com/science/article/pii/S0271531711000911?via%3Dihub (very wide range of carbohydrate intakes, though all lower than current recommendations)
BUT WHAT ABOUT TEH KITAVANS (traditional horticulturalists, eat a diet very high in carbs from tubers and saturated fat from coconut, apparent absence of heart disease, suggesting that high-carb per se is not a problem): https://www.gwern.net/docs/nicotine/1994-lindeberg.pdf

https://www.nationalgeographic.com/foodfeatures/evolution-of-diet/ -- interviews with researchers, round-up of the incredible diversity of hunter-gatherer diets

[rydra_wong]

Health: there is a well-documented decline in certain aspects of health as shown in skeletal evidence when humans invent agriculture.

Agriculture can support a higher population density, but people get shorter, their teeth get worse, and there's more infectious disease (probably from increased population density and maybe living in closer quarters with farmed animal populations -- this stuff is not necessarily due to diet). This does eventually reverse, but not until relatively recently in human history:

https://www.sciencedaily.com/releases/2011/06/110615094514.htm

Hunter-gatherer populations typically have excellent metabolic and cardiovascular health (lower life expectancy at birth is largely due to infant mortality):

https://onlinelibrary.wiley.com/doi/full/10.1111/obr.12785 (completely fascinating in multiple respects)

[ironed_orchid]

This article from last year on why dieting doesn't work is really good, and may help to counterbalance people who fixate on ideas about obesity and BMI:

Everything You Know About Obesity Is Wrong, Michael Hobbes

[kore]

I liked that one quite a lot, especially the photographs.

[rydra_wong]

- What is the deal with "calorie reduction makes you healthier and live longer" vs. "dieting is bad for you?"

WE DUNNO. AFAIK, right now it's all a big mess of fruit flies, mTOR, autophagy and speculation.

Also there may be some sort of trade-off between absolute maximum longevity and physical performance/well-being in the medium term?

There are hints that there may be some mechanisms that kick in during food-deprivation that it may be beneficial to have switched on some of the time.

Which is one reason why there's so much self-experimentation with different versions of intermittent fasting going on, to see if you can get benefits without having to restrict your total food intake (however, there's also anecdata that intermittent fasting can work out badly for at least some women).

One that's got some interesting research behind it is "time-restricted eating" (Google Dr Satchin Panda, who has serious researcher cred) -- it looks like restricting your eating to a window as wide as 12 hours (so if you eat breakfast at 8am, you'd have supper finished by 8pm) can have significant benefits.

However, it looks like this is strongly related to circadian rhythm stuff.

Anyway, it's all very speculative. But (I am not a researcher) it looks much less like "CALORIES BAD", more like "there are some mechanisms that kick in at times when we're not eating, we maybe want to have those activated sometimes?"

[recessional]

Yeah honestly it's mostly "there's so much variation here we may literally never know" - a HIGHLY RELEVANT QUOTE from this CBC health-article: "A large grain of salt": Why journalists should just avoid reporting on most food studies:

Haber has a particular interest in those types of headlines because he studies the way scientists and the media deal with causal inference — whether the evidence is strong enough to establish a cause and effect.

In most nutritional research, it is not. And nutrition researchers know this. They are careful to report their findings as being "associated" or "linked" to a specific outcome, whether it's a disease or risk of death, or something positive like longer life.

[....]

"Unfortunately, we cannot get solid answers about common nutrients and common foods with the same epidemiology tools we use in other domains."

That's because in dietary research, there is just too much noise, he said.

Most nutritional studies are based on observational data collected by asking people to remember what they ate and then running statistical analyses looking for links between nutrients and a particular health outcome, such as cancer.

Problems include the vast assortment of confounding factors: Are overweight people also under extra stress? Are red wine drinkers also wealthier? Are people who eat lots of processed food also struggling with lower incomes?

Add to that the differences in age, genetics, sleep rhythms, education levels, access to recreational facilities and community health services and on and on. With 250,000 different foods consumed in endless combinations, the constantly changing circumstances are too complex.

"Individuals consume thousands of chemicals in millions of possible daily combinations," Ioannidis wrote in an article published in JAMA last month.

"Disentangling the potential influence on health outcomes of a single dietary component from these other variables is challenging, if not impossible."

Researchers try to account for the confounding variables, but Ioannidis said they can't eliminate them. Eating is too tightly wound up in other social and behavioural factors that can affect health.

Emphasis mine.

And that's not even a REMOTELY full list, as there's also the full range of "do you have this odd/rare genetic combination?" "were you subject to traumatic stress as a child and did you get a bunch of electrolytes after it?"

It gets to the point where the factors involved become "is the moon full?" and "did your cat sneeze?"

It's just very, very complicated and we're so far from being able to determine signal to noise in most cases, especially around fiddly bits (that is, more complex than "eat food, lots of plants, not too much, move around a bunch including some that raises your heart-rate") that it's not even funny.

[duskpeterson]

Okay, now you've got me wondering whether https://www.choosemyplate.gov (which is a revision of the Food Pyramid, which is a revision of the Four Food Groups, which is a revision of the Seven Food Groups) has any solid science behind it. Is it like climate change, where there's a consensus on the basics by 99% of the scientists, or is this a case where the U.S. government nutritionists threw up their hands and said, "Well, heck, this one looks good"?

[thomasyan]

solid science behind it

Well, I think companies have studied how to effectively lobby. So at least in that sense, there is probably solid science/experience. For the science we want, maybe not so much.

[rydra_wong]

What is the best and most cutting-edge knowledge on gaining strength?

Stuff on which there's a LOT of consensus:

Lift heavy things (including your own body), for something in the region of 3-12 reps (exact range within that depending on whether you're aiming for pure strength of some hypertrophy or strength-endurance), at a weight where that's your limit, three sets are better than one set, have at least a day off before you hit that muscle group hard again, eat enough protein for muscle growth, people over about 40 need more protein for that than younger people do.

Climbing-specific strength is weird because a lot of what we need is isometric finger strength, which has to be trained differently from isotonic (concentric/eccentric) strength.

[rachelmanija]

The "never train the same muscle groups on consecutive days" is actually one of the things I was wondering about. Everything I've ever read says that, but after one month on crutches in which I had to do the same weight-bearing exercise every day whether I liked it or not, I've broken through a strength plateau and now have bigger arm muscles and noticeably improved upper-body and grip strength. I was never able to get that with standard weight training every other day or every three days.

[philomytha]

I found Stephan Guyenet's 'The Hungry Brain' worth reading and very much grounded in science. It's largely about the neurobiology of overeating, basically, what affects your brain's signals about hunger and fullness and what affects whether you decide to eat or not eat something.

[rachelmanija]

Thank you!

[monanotlisa]

Hmm, I'll be subscribing to the answers to this post -- very good question.

[rydra_wong]

Saw this and thought of you:

https://www.frontiersin.org/articles/10.3389/fnut.2019.00066/full

FRUIT IS SAFE OKAY.

[rachelmanija]

LOLOLOLOL.

I just posted on body composition changes due to a month and a half on crutches, BTW.

[kore]

Not sure if you're still looking, but this was a fascinating and actually scientific (Randomized, controlled research) look at people eating super processed v unprocessed food -- its one of the most scientific studies I've seen, since they tracked stuff like hormone changes and blood glucose levels and other metabolic changes quite closely

https://www.npr.org/sections/thesalt/2019/05/16/723693839/its-not-just-salt-sugar-fat-study-finds-ultra-processed-foods-drive-weight-gain

https://www.nytimes.com/2019/05/16/well/eat/why-eating-processed-foods-might-make-you-fat.html

"The perpetual diet wars between factions promoting low-carbohydrate, keto, paleo, high-protein, low-fat, plant-based, vegan, and a seemingly endless list of other diets have led to substantial public confusion and mistrust in nutrition science" https://www.cell.com/cell-metabolism/fulltext/S1550-4131(19)30248-7

"LANDMARK findings that food processing - not fat, sugar, salt, carbs, or even fiber - drive over-consumption, while minimally processed, phenolic-rich foods drive gradual weight loss. Likely starving vs. nourishing the microbiome too." https://twitter.com/Dmozaffarian/status/1129120688177131522 (Dean of school of nutrition at Tufts)

Everyone is focused on "it makes you fatter" &c &c but I was more intrigued by how people on the ultraprocessed diet ate more, felt less satisfied, and there were apparent significant impacts on their health.

[rachelmanija]

Those look really interesting, thanks!

[cimorene]

A few areas of nutrition and health science that I've read about recently:

Tim Spector's research on the gut microbiome and its impacts on health (if what he says is true, it's probably contributing to the results mentioned above about the negative effects of processed food): The Diet Myth is his book; there are excerpt/articles and videos like "What Role Does our Microbiome Play in a Healthy Diet?" from the Royal Institute floating around. Apparently he's been doing this research for some time, but it probably still counts as 'new' since it's not widely known or accepted by doctors and science journalists...? To promote the health of one's own gut microbiome with diet, he advises maximizing diversity with different foods from as many sources as possible, as well as emphasizing fibers, fermented foods, and polyphenols.

A few months ago I saw a TED talk (Segal, "What is the best diet for humans?") about this 2015 study, Personalized Nutrition by Prediction of Glycemic Responses, which found that the "ideal diet" actually varies tremendously from person to person because which foods cause blood glucose spikes varies from person to person. "Glycemic Index" is supposed to tell you how much of a blood glucose spike an individual food will produce (hence you'll get things like 'But ACTUALLY white rice has a higher glycemic index than [carb-based dessert food]'), but it's based on average values that aren't guaranteed to hold true for any individual.

I recently read a short recommendation for The Salt Fix, a 2017 book by a cardiologist claiming that salt has been erroneously blamed for high blood pressure without other factors being adequately controlled, and that a diet too low in salt is more dangerous to the health than a diet with more salt than your body needs. I gather there isn't really enough research to support this position right now and that it all hinges on arguing about how studies have been interpreted, so I doubt this book is going to provide me with a definitive answer, but I intend to read it anyway, not least because I'm always suspicious of 'accepted wisdom' medical advice about which doctors are as passionate as they are about the salt one.

[conuly]

- Do we actually know anything about nutrition, given the every-five-year swings between "eggs are cardioprotective/eggs are a heart attack on a plate," "fat is the Devil/carbs are the Devil," etc? If so, what is it and how do we know it?

Actual scientists are not making those swings, the media is in its chronic churn. The data says something like "a reasonable amount of eggs, in moderation, are probably good for you, but eating too many is probably bad for you" and "all humans need fat/carbs/protein in reasonable proportions, which no doubt vary according to genes and lifestyle in ways that we're still working out".

[rachelmanija]

Can you rec some books or articles that go into depth on those topics, such as what is meant by "a reasonable amount," "in moderation," "in reasonable proportions," and "too many?"

And, also our measurement basis is imprecise

[jesse_the_k]

Is the conclusion I drew from a long article in The Economist
https://www.1843magazine.com/features/death-of-the-calorie
By Peter Wilson
DEATH OF THE CALORIE

The history of the calorie as a measurement of food value is checkered and confusing, and wildly inconsistent.

[ewt]

Hello, I am here from silveradept's post.

I think most of the things I was going to say have been covered, but where people talk about the glycaemic index, it might be interesting to look at the insulin index of foods. This has only been calculated for a smallish number of foods yet (and measuring insulin is more expensive than measuring glucose and, notably, much harder to do at home -- which means you can't easily construct your own, personalised insulin index the way you theoretically could for a glycaemic index) but has some interesting bits in; sorry, I am using my phone and do not have the link to hand, will try to come back from a big computer.

I would also add that a lot of the animal studies are... not great? I mean, if we are testing stuff on mice who are obese because of a specific genetic mutation, it might not apply to humans (who can't be assumed to have that genetic mutation).