December days: Health at every size

[liv]

A while back, I made a post related to weight loss dieting, and in the comments, shreena asked me why I do believe that politically and scientifically, health at every size and similar approaches are 'better' than weight loss dieting, commenting:

I'm interested in the evidence base on this. I have not looked into it so I don't really have an opinion but I'm interested by the fact that many intelligent knowledgeable friends of mine hold the view that you [...] have expressed but so many health institutions and guidance hold the opposite view (i.e. that health and size are correlated.)

I possibly shouldn't have shoved this in with the December Days prompts, because really I want to put in lots of links to evidence rather than just writing off the cuff as I end up doing when I'm trying to post every day. But equally, I don't want to duplicate the work that lots of other fat acceptance / HAES bloggers have done really comprehensively, so I'm going to try a brief run-down here, and follow up in the new year if this isn't satisfactory.

In order to address this prompt, I am going to talk about weight loss and dieting and also about the medical establishment's attitude to fatness and fat people. My plan is to take this post in a fairly sciencey way, given shreena asked for the evidence base. I have a political opinion, which is strongly body positive and against medical and other discrimination against fat people. But I'm going to try to be as neutral as I can, and I'm going to entertain various possible interpretations of the evidence that I'm discussing. I'm aiming to present a case to intelligent, open-minded skeptics, basically, and I appreciate that even acknowledging the possibility that fatness may cause bad health is going to be offensive or upsetting to some people.

Further, I'm talking purely about the connections between size and health. I am committed to the view that health is not a moral imperative, so even if I saw enough evidence to completely convince me that it's always healthier for everybody to be as thin as possible, I would still argue that people have the right to choose whether they want to go on weight loss diets or not. But that's not the point of this post, I want to explore the question of whether losing weight actually is beneficial to health.

I should also warn about the comment discussion that might come up. I didn't do so last time I discussed this topic, and some of the comments ended up upsetting some friends – I'm very sorry about that. I generally get a lot of pushback when I talk about this sort of topic, because some of my friends are more politically radical than me, and some are convinced by the orthodoxy about fat and health. I hope everybody will be civil and sensitive about discussing a fraught topic, but I expect a fair range of opinions here. I may also not have time to answer comments, partly because it's about to be Christmas and partly because I'm trying to keep up this daily posting for another couple of weeks, given it's been so satisfying up to now.

As I said, there's a lot of good stuff available examining the evidence for and against weight loss dieting for health, and I'm relying quite a lot on secondary and tertiary literature, I haven't personally examined every single study about weight loss ever published! Though I have read quite a lot of them, both several that support my view and several that do in fact show weight loss is good for health outcomes. I strongly recommend the blog Junkfood science which has absolutely masses of links, and basically anything by Paul Campos, who has a number of articles online but no centralized blog, but who has written a book, The obesity myth which goes over a lot of the relevant science as well as the reasons why the science is ignored or misinterpreted.

I think the thing that caused me to question the assumption that fat people should lose weight to become healthy was probably something like this ancient link round-up, which cites a number of peer-reviewed studies that come out against intentional weight loss and in favour of HAES. There have been, to my knowledge, several large, high-quality studies in the most recent decade that point in a similar direction. However there have also been a great many studies that show beneficial effects of weight loss, so I don't want to just cherry-pick the stuff that agrees with my beliefs. I want to talk in fairly general terms.

So, with that preamble, my first point is that health and size are correlated is not actually the "opposite" of health at every size and similar approaches are 'better' than weight loss dieting. There may in fact be a correlation between being fatter and having poor health outcomes, and there is indeed some evidence for such a correlation, though also some evidence against it, as I shall go on to discuss. But that doesn't at all imply that deliberately restricting calories in order to lose weight will make a currently-fat person healthier. Being fat may be correlated with ill health, without being the cause of it, in which case losing weight won't help. Being fat may be the cause of (some) ill health, but losing the extra weight may well not fix the damage potentially caused by being fat in the first place. Finally, losing weight may be good for (some) people, but, contrary to what naively seems expected, restricting calorie intake, ie what people normally mean by dieting, may not be a good way to achieve weight loss. In fact my knowledge of the research leads me to conclude that all of these maybes are in fact true.

Is fatness correlated with ill health? There are certainly some studies showing such a correlation. Particularly studies of people who already have a serious illness, such as heart disease or diabetes; in such groups, the fattest individuals tend to have the shortest life expectancies. There is also pretty sound evidence that really extreme obesity is correlated with poor health. However, in long term studies of the general population, there's more and more evidence that people classified as overweight live longer on average than people classified as "normal" weight, and even some evidence that people classified as obese, but towards the lower end of the range so classified, have the same or better life expectancies as people classified as normal weight. So at the very least the range of weights considered healthy or unhealthy are pretty dubiously evidenced.

Also, BMI, which is the easiest thing to measure and the most commonly used in studies of the health effects of obesity, is really not very well correlated with actual fatness; it is merely a ratio between weight and height, so it's affected by things like proportion of muscles and ethnicity and body type. Now, of course the answer to this is to use actually meaningful measures of fatness, such as body fat percentage, waist to hip ratio and so on, but a huge number of the studies that make claims about size and health in fact rely on the rather unscientific measurement of BMI, so you have to be careful in how you interpret them.

Further to this, there are at least some big, high quality studies which show that fatness stops being correlated with poor health if you correct for confounding factors. A big one is the Framingham study which is the absolute gold standard in risk factors for heart disease, since it's been following thousands of people for over 60 years. This shows that being overweight has little or no effect on heart disease risk if you correct for race and socioeconomic status and things like that. I mean, there's a strong correlation between being overweight and being poor; maybe it would do as much good to give people more money and resources as to deny them calories. There's this study which really shows that fatness is only an additional risk factor in people who also smoke and drink too much alcohol and do no exercise and don't eat any fresh fruit and vegetables.

But the problem with any statistical analysis that corrects for confounding factors like this is that you don't know that they're true confounders, they may in fact be relevant to the effect you're trying to use. Some people will dismiss the lack of effect of fatness alone seen in Framingham and similar results as irrelevant because there are very few individuals who are actually rich and healthy and have all these other advantages who are also very fat, even though the statistics predict that such people would be expected to be just as healthy as similarly advantaged thin people.

Correlations aside, I have seen very little direct evidence at all that losing weight improves health outcomes. And believe me, I've looked for it. It's usually just assumed that if fat people have worse health, then losing weight must improve health. But that doesn't follow at all; it seems actually quite likely that if being fat is bad for you at all, the damage caused by being fat is irreversible or at any rate poorly reversible. I've seen people trying to disappear the inconvenient result that the lower end of the supposedly overweight-obese range is correlated with longer lifespan by stating that the important factor is the highest weight people have ever been; some normal weight people may in fact have bad health because they were once fat and then lost the weight. Which is a plausible explanation but has never been proved either way, and if that is the case there's not a very good reason to encourage fat people to diet!

There is very mixed evidence about "weight cycling"; some studies purport to show that fluctuating weight, as you might see with someone who diets and then regains weight repeatedly, have worse health than people who remain at a constant weight, even if that weight is higher overall. On the other hand I have seen those studies hugely criticized, and many people who seem to know what they're talking about will vehemently deny that there is any harm associated with weight cycling. This is one issue I haven't really come to a conclusion about, I'm just telling you there are competing claims out there. And it seems at least plausible that big changes in weight may be as harmful or more harmful than having a high absolute weight, or indeed that dieting itself may be bad for some people.

Anyway, in summary, there is some evidence that high weight is correlated with poor health, especially very high weight. There is some evidence against this view too, but I'm reasonably prepared to believe there is sometimes a correlation there. But there is little evidence that losing weight improves health. So (in spite of my hardline political stance) I think it's probably medically worth it to try to maintain a lifestyle that prevents major weight gain, but once you are already fat, I am not at all convinced it's worth going on a diet to lose that weight. Or at least, if you want to be healthy, eating a balanced diet (without calorie restriction) and doing plenty of exercise have both been shown very clearly to have beneficial effects. Along with other things like getting enough sleep, drinking in moderation and not smoking at all and some mental health things that are a bit complicated to discuss here. Whereas the evidence for weight-loss dieting is extremely equivocal.

Which brings me to my third point. One of the major reasons there isn't clear evidence about whether weight loss actually helps is that successful weight loss is surprisingly rare. The huge majority of people who attempt to lose weight by dieting regain as much as they lost or more within a few years of stopping their diets. Fat activists claim that it's about 5% who lose weight and keep it off, but it's not very clear where that figure comes from. I mean, I've seen peer-reviewed studies of diet methods that claim a higher success rate than that, though my general impression is that they tend to be fairly short term.

But it's not unusual to see studies claiming that a method of losing weight is "successful" when the amount of weight loss is really tiny, like a few kg on average even after really intensive support and not counting all the study participants who gave up the diet before they'd completed it. Here's an example where the conclusion was that low-calorie, low-fat and low-carb diets are equally good, while what the numbers actually say is that fewer than 1 in 6 of the people who successfully stuck with their strict diets had lost 10% of their body weight and kept it off after 2 years (no matter which method they used). And, well, if someone was classified as obese or extremely obese when they started their diet, losing 10% of their body weight usually isn't going to put them even close to a so-called "normal" weight category. I haven't got links to hand but it's interesting that even bariatric surgery has a fairly high failure rate (like 30-50% IIRC, but that's not going to be convincing if I can't show you the cites); even among people who have had their stomach stapled or half their digestive tract removed, who therefore physically can't consume "too many" calories, many regain much of the weight they initially lose.

But again, I don't want to cherry-pick studies just because they support my view. I think one of the most interesting is the Look-AHEAD study, which is one of the biggest and most rigorous diabetes studies, which researchers halted because they weren't seeing any improvement in health outcomes based on their weight-loss interventions. And that's some pretty serious health intervention, the people in the study were getting way way way more support than your average dieter, even one who signs up for a guided programme like Weight Watchers or Slimming World or whatever. But the weird thing about that study is that they claimed that their interventions were "successful" in producing important long-term weight losses and improvements in cardiovascular disease risk factors among a significant proportion of severely obese individuals, but when you look at the numbers, it turns out what they're calling "important" is an average weight loss of 5% after 4 years, and with error bars of ±7-8%. That is, even the most intensive and best evidenced weight loss intervention you could ever imagine only helped people to lose about 5% of their body weight; if they were severely obese to start with they were still severely obese by the end. And, well, those error bars are bigger than the absolute average weight loss, which strongly suggests that some people gained weight. Now, that's people with type II diabetes, so it's possible that people who don't have diabetes are more easily able to lose weight. But still, it's kind of suggestive.

I find it very plausible that most people (not all, but most) have a natural set-point for their weight. The body has mechanisms to keep weight constant, even with increased calorie intake and decreased calorie output, or (as the typical situation of a dieter), restricted calorie intake and increased activity. It would make evolutionary sense to try to hold weight constant through fluctuating food availability, wouldn't it? And that's made more plausible by the cluster of studies that show very small changes in weight, or changes that are reversed as soon as the intense diet phase ends, even with quite drastic changes in calorie balance. Of course the set-point is not absolute, it seems to gradually creep up with age, and hormones and some drugs affect it. But there probably is some kind of homoeostatic mechanism in play there.

So, maybe weight loss would hypothetically be good for people's health, but for many people it's not actually possible. Not without really quite extreme measures, anyway; most commercially and even medically promoted weight loss diets are nowhere near enough to bring about long-term, large scale reductions in people's weight. So that means that people are putting lots and lots of effort into something that's extremely likely to fail, especially if the goal is to change from being very fat to being the medically approved "normal" weight. Whereas if people were to put the same amount of effort into improving their stamina and cardiovascular fitness and eating healthily and so on, they would probably get many if not all of the health benefits anyway, without having the extremely discouraging effect of not achieving their goal. Because outside of strictly controlled experimental studies, many many people give up their diets if they find they're not losing weight or they are regaining what they lost. So that's basically the HAES thing, people should try, or be supported if they're in a situation to get medical support, to actually live more healthily, without worrying about the number of kg they weigh. Especially since that number is only very dubiously connected to health and is also, for most people, pretty hard to change.

And my final reason for saying that HAES / weight neutral health initiatives are better is that insisting on weight loss does measurable harm. It makes people hate themselves, and people who hate themselves aren't very likely to alter their behaviour to be more healthy. It can also exacerbate eating disorders and other mental health problems. So even as far as it's true that health and size are correlated:

• there is weak evidence that losing weight actually improves outcomes
• losing weight is rather difficult to achieve, especially losing enough weight to change fat people into normal weight or thin people
• weight loss diets and insisting on weight as a measure of health do actual harm

Does that help? Basically that's where I'm coming from on the issue, scientifically, though my political views do follow on from and extend that. I don't think it's going to be enough to help my brother and his housemate argue against the weight centric approach being applied to care home residents, but it's the best I can manage in an evening.

[December Days masterpost]

Comments

[jack]

*HUGS* Thank you for managing to write this.

[jae]

This is great, thanks.

When the researchers talk about "weight cycling," do you know how much weight lost and gained is generally meant? I have never deliberately tried to lose or gain weight, so this is not a psychological issue for me, but due to various other factors (like fluctuations in my activity level and eating patterns), it has historically not been uncommon for me to lose or gain, say, 20 US pounds over the course of any given year. My minimum exercise level has been pretty stable since late 2011, so this has gotten a little better, but it's still not unusual for me to lose or gain 10 US pounds in a given year. (Basically, I just lose AND gain very easily.) Does that count as "weight cycling", or is that a small enough range that it's close enough for government work?

For clarification purposes: this isn't something I worry about per se, it's just that I've always been curious whether or not they mean me when I read about weight cycling.

-J

[woodpijn.livejournal.com]

I'm a bit like this; my weight naturally fluctuates quite a lot without any deliberate choice on my part.
I don't much care whether I'm a size 8 or a size 14[*] if only it would stay the same and my clothes would fit!

[*]the typical range of the fluctuation

[ljgeoff]

I was just thinking something similar -- it's such a hassel to have clothes that don't fit! I don't have enough time nor make enough money to find something that might fit me just right. And I don't like yoga pants. Size 20 used to fit me just right, but then I lost some weight and my muscle to fat ratio shifted a bit and my old clothes no longer fit, but at the same time, I can't fit into the next size down, either. I'm considering a concerted weight loss and toning effort so I can fit comfortably into a size 18. Stupid clothes.

[jenett]

One of the complications is that *changes* in weight can be medically useful data, if one can manage not to get hung up on the idea losing weight always being a good thing.

In other words, I can see an argument for monthly weighing in a care home or something equivalent, so long as precautions are taken to allow people to avoid knowing the numbers if they don't want to (and that weight loss is not praised or weight gain scolded. This part is really really hard in our culture.)

I keep thinking back to the fall before my hypothyroidism was diagnosed, where I went *hyper*thyroid for a bit (common in people where it's an autoimmune issue) where I lost more than 10% of my body weight in a couple of months (I am sizeably fat) and the only thing I heard about it was praise. It was never marked as "Hey, you haven't changed your habits that much, that's weird, let's check that out." and even though I brought it up when I was pushing for more thorough testing, it took me several rounds to get it taken seriously.

(And as a note, my weight bounced back to my general set point I've been near for 10 years after shortly thereafter.)

My current health care provider weighs every visit, but it is very explicitly treated as 'we want to make sure there hasn't been a noticeable change without some understandable reason', the same way they check my blood pressure or my pulse or whatever. (And where a single unusual reading probably isn't a big deal, but two in a row is a lot more cause for concern.)

I am also not required to see the number if I don't want, and they have been very good about my saying "I care about my overall health, I do not want to valourise weight loss, because Bad Things Happen In My Head When You Do That."

I do have health issues that the weight probably isn't helping, but my exercise is more limited by lung scarring from pneumonia when I was 11 (and asthma) than it is by the weight. Funny how no one really has a solution for that.

[azurelunatic]

One of the things which helped me in light of teenage trauma around a parental role model with overwhelming somewhat manic self-loathing-with-dieting cycles was frequent blood plasma donation, where your weight is checked and logged (I don't know if it would have been possible for me to avoid knowing the number in that setting, but limiting the frequency to twice a week maximum was great) and any loss greater than 10 pounds in a rolling month was inquired about with deep seriousness, as unexplained weight loss is of course a possible symptom of a great many things that would not be pleasant to have loose in the blood-and-blood-products supply. So I got it conditioned into me that rapid weight loss is a cause for valid medical concern, especially if it's unexplained. Which made me retroactively very sorry for my teenage self and the praise I was getting for making some very poor choices in pursuit of unnecessary and I think ultimately damaging weight loss.

[woodpijn.livejournal.com]

Very good thoughtful reasoned post, thank you. My previous experience of health-at-every-size people has been that they are very angry about the prevailing view and not very prepared to have reasoned discussions about it, so this is very helpful.

I have a related question that's linguistic rather than biological. You use the word "fat". I would be very hesitant about calling you, or anyone else, fat. Do you consider it a neutral descriptive term, or one of those reclaimed words that you can only use if you are it, or something else?

[rmc28]

I'm not Liv, but I am fat, and my view is that I think 'fat' ought to be a neutral descriptive word, but socially it very much isn't - which I think is where your hesitation to call anyone fat comes from. The more I can matter-of-factly use it, the less the social disapproval has power over me (and perhaps people around me).

So e.g. when my son mentions that I am fat, I agree cheerfully. He is right, I am fat. I want him to understand that being fat is not a Bad Thing, and I do my best to model that to him. (I might not always feel that way, but the more I fake it, the less power the social disapproval has over me.)

I call myself fat. I find it harder to call other women fat because of the strong social sense that I might be insulting them. I do my best to ensure that I react to people calling me fat as though they have said something neutral and factually correct. (which they have)

[(Anonymous)]

I dislike ephuisms, but I might use "plump" when I really mean "fat"...or maybe not. What I think of as "fat" implies concern about diabetes & other health problems connected with more than trivial overweightness. I guess I might use that word to them, but not when writing about them. And hey, I know one person who is no more than hefty above the waist, but grossly obese below it -- clearly a genetic problem, not a dietary one... and I just don't talk or write about this, nor does it ever enter my interactions with him.

[(Anonymous)]

Oops! I don't know how that comment (beginning with "I dislike ephuisms" (which might not be spelled correctly) got posted as "anonymous", but it was written by Don Fitch, who has never posted anything anonymously, intentionally.

[ghoti.livejournal.com]

*hugs* thank you for writing this.

[davidgillon]

Possibly worth noting around the 'fat people have worse health' thing that in a lot of cases it's putting the cart before the horse/confusing correlation with causation. There are a whole bunch of illnesses with metabolic effects, and an even wider use of medications with weight gain as a very common side effect. Steroids are probably the ones everyone knows, but I've had noticeable weight gain while using both amitriptyline (an anti-depressant) and gabapentin (an anti-convulsant) for pain control. In the case of the gabapentin (which I never wanted to be on in the first place, but my GP was being pressured over opiate prescribing) I was gaining 2 pounds a month with no change in activity levels or diet, I stopped the gabapentin due to the weight gain and the weight started coming off me at about half the rate it went on (and once I did stop it I realised there'd been some nasty psych side-effects as well). That was around a 10% increase in body mass in 6 months solely due to medication, in BMI terms it was very nearly enough of a change to tip me over into the obese category.

This is why I *headdesk* every time a Clinical Commissioning Group or whoever announce they plan on restricting access to joint surgery to overweight patients until they lose weight. Almost inevitably the weight gain is due, at least in part, to medication effects and reduced activity levels, which mean they're not encouraging weight loss, they're actually punishing the patient for being disabled and needing medical support. Or worse, they know this, and are using it as an excuse to cut the budget by forcing the patients to jump through hoops before they can access the service.

[princessofgeeks]

Thank you for this.

[siderea]

Marvelously put.

[silveradept]

This makes excellent sense, and appears to be a well-supported position.

Observations on a couple of doctors

[eftychia]

My mother is fat. Fat enough to affect how she can bend and probably part of the reason she can't get herself up when she falls. She gets weighed at each visit to her doctor. A couple months ago, she had lost a few pounds. Her doctor said to add Glucerna to her diet because he didn't like the weight loss: at her age some serious illness or injury is nigh inevitable and he wants her to have enough fat reserves to get through that when it happens.

I am fat, eighty pounds heavier than the weight where I felt most physically comfortable and best liked how I looked. When I started seeing my current doctor eleven months ago, he said nothing about my weight until late summer when my weight had increased three months in a row. From his phrasing and tone of voice I got that he was concerned about the change, not my absolute weight. (I am on medications that tend to increase weight.)

Neither doctor has explicitly invoked HAES, but both have been surprisingly not thinness-obsessed. I do want to lose weight (maybe not all eighty pounds since my body has changed in other ways in the decades since I was that thin) but I'm really glad my doctor isn't trying to blame most of my problems on my weight or make it a priority. (I haven't asked him how much weight he thinks it would be okay for me to lose. And if I never lose any, well I've got much bigger issues than that to worry about anyhow.)

I will be disappointed if I can't improve my stamina a bit, and that's more important.

Re: Observations on a couple of doctors

[azurelunatic]

Stamina is a great thing to gain. I'm enjoying mine a lot!

[shreena]

Depressingly, I have to work this morning (boo!) so will post a proper comment later on - I just wanted to say thank you for taking the time to write this, it's very interesting and I particularly appreciate the focus on the evidence base.

[falena]

Thank you so much for writing this.

[(Anonymous)]

So, if people have a set-point for weight/fatness .. why is that set point, on average, getting ever higher? Look at crowd footage from (say) the UK from the 70s and from now. Most people now are WAY WAY WAY fatter.

[ceb]

Food rationing in the UK only finished in 1954.

[(Anonymous)]

OK, so *if* rationing in childhood is the explanation, then that argues food restriction DOES work, and 'set points' are not so 'set'...

[ceb]

I think it more strongly argues that food habits can be set by rationing (and if there's one thing weight loss and behaviour change studies do consistently show, it's that habits are very hard to change).

ETA: I'm thinking more of adults' response to rationing; e.g. I think there are people in my parents' generation who eat lots and fed their kids lots because they remember growing up with little.

[(Anonymous)]

I think it more strongly argues that food habits can be set by rationing

But the point is that it more directly implies that food habits have an effect on size, doesn’t it?

[kaberett]

The same phenomenon is observed globally and cross-species, including in lab animals whose diet has been recorded in painstaking detail throughout. We don't know why, but it's not ~people being awful~ or whatever.

[(Anonymous)]

I find it very plausible that most people (not all, but most) have a natural set-point for their weight. […] Of course the set-point is not absolute, it seems to gradually creep up with age, and hormones and some drugs affect it.

That thing about it not being fixed, though, I’m not convinced there isn’t a feedback loop where if you gain fat the body decides that gaving energy stores is ‘the new normal’ and steps up the set-point.

You can see where that would be useful, evolutionarily: in times of plenty, it would be of benefit to build up as much of a store as possible, and try to maintain it as hard as possible through intervals of shortage (weeks, months, even years) in order to be ready for the Big Famine.

I know I got lardy when I got an office job but kept eating like a student, and it took a couple of years of cutting out chocolate and going to the gym to get my body fat back into single digits and even several years later it is still proving difficult to get down to 5-6%, and I can’t help thinking I have myself to blame: if only I had not let myself bloat, I wouldn’t be in this position now.

[ceb]

it turns out what they're calling "important" is an average weight loss of 5% after 4 years, and with error bars of ±7-8%

It's worth pointing out that small weight losses *are* important in diabetes, that's not just the researchers overblowing the results. There's increasing evidence that everyone has a (different) bodyfat % at which some metabolic processes tip over from this-body-is-coping to this-body-is-not-coping, and small weight losses can be enough to tip them back (depending on an individual's exact situation &c. &c., and probably only for a limited period of time as people's glucose regulation tends to get worse with age).

[redbird]

I suspect we're looking at the difference between clinically significant and statistically significant. If it's true that for the individual, losing 5% of body weight is medically important, it's also true that for the next individual, gaining 3% is likely to be.

The individual patient who is being offered this intervention should be told both that it might help them lose weight, and that they might put in lots of effort and gain weight. In other words, they should treat it more like prescribing a drug: a competent doctor, if she offers Prozac, will warn the patient that there is a small but important chance that it will increase rather than relieving depression.

[quizcustodiet]

I'd like to echo everyone's thanks above, as I found this really interesting to read. It also flushed out in my head the way that when reading about health issues I've conflated things which are correlated with cardio-vascular fitness (e.g. dementia, which terrified me into starting back at the gym!) with things that are correlated with weight alone.

It raised a couple of further questions for me which I'd be interested in your thoughts on as someone who works in the field. (There can be a certain amount of physical sciences/biological and social sciences incomprehension, as I found when I was reviewing a paper and they started talking about the 90% confidence interval. Totally not a thing we talk about in my area of physics!)

I was interested in your comments about BMI being a weak measure of fatness. I was aware that it was not great as a measure for an individual, but I'd understood that it was much more useful on a population basis, not least because you can build a much bigger research sample if you can use data that is routinely recorded in medical records like height and weight than if you have to do a bespoke body fat % measurement. I gather from your comments about research studies that you don't think it's useful even for population level stuff: are the natural variations that big? I would naively have assumed that there would only be 10% or so who were very badly described by BMI, and that they'd be evenly enough spread across the 'healthy, but BMI says overweight/obese' and 'unhealthy, but BMI says normal' that it wouldn't be a big issue overall.

The other thing I was surprised not to see covered is (as Foresight put it) the 'obesogenic environment'. Their argument (as closely as I can recall without reading the report again) was that the type and prices of food that we have available and the way we design our towns and cities and manage our lives all conspire to mean that the default choices will lead to weight gain and, in the longer term, obesity. To counter that, they would argue that we need government interventions like sugar taxes, cycle lanes, etc to shift the defaults back to make it easier not to gain weight in the first place. From what you've said, it sounds like that would all be consistent with your view of Health at every size, but I'd be curious to know if you think it's actively a good thing or not.

[naath]

BMI, crock of shit> me and my size 8 jeans would like to wonder why I'm "overweight", and in that case what "normal" even means (I'm cheating, I'm made of muscle, and like snugly-fitting jeans, but anyway) (I actually visited size 6, and a "normal" weight last summer, but I was kinda ill, and also still had visible body fat, and it wasn't really a good look) [this is kinda a random point to add, but I feel sort of weird identifying as either "fat" or "not fat" on account of how my weight and dress size tell very different stories]

I think there seem to be good arguments in both directions on "is it bad for you to be fat", but I really really don't see why "being rude to people" "for their health" is expected to cause them to change their behaviour at all (even supposing behavioural changes "worked"). AFAICT being rude to people about their "bad" habits is just about the best way to make them do them *more* not less!

There are also huge social issues about access to a)accessible exercise and b)healthy food that never seem to be addressed by the "eat less, exercise more" crowd.

[ephemera]

Thank you for putting this together ;)