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Being Slightly Overweight May Lead To Longer Life
Hugh Pickens writes "Findings of a new study show that underweight people and those who are extremely obese die earlier than people of normal weight — but those who are only a little overweight actually live longer than people of normal weight. 'It's not surprising that extreme underweight and extreme obesity increase the risk of dying, but it is surprising that carrying a little extra weight may give people a longevity advantage,' said one of the coauthors of the study. 'It may be that a few extra pounds actually protect older people as their health declines, but that doesn't mean that people in the normal weight range should try to put on a few pounds.' The study examined the relationship between body mass index and death among 11,326 adults in Canada over a 12-year period. The study showed that underweight people were 70 percent more likely than people of normal weight to die, and extremely obese people were 36 percent more likely to die. But overweight individuals defined as a body mass index of 25 to 29.9 were 17 percent less likely to die than people of a normal weight defined as a BMI of 18.5 to 24.9. The relative risk for obese people was nearly the same as for people of normal weight. The authors controlled for factors such as age, sex, physical activity, and smoking. 'Overweight may not be the problem we thought it was,' said Dr. David H. Feeny, a senior investigator at Kaiser Permanente Center for Health Research. 'Overweight was protective.'"
Someone with a high BMI might be overweight - or they might be in really good shape and have lots of muscle. Just something to think about.
My blog
Then let me ask this. If slightly overweight seems to be healthy, then how was the "ideal" weight range determined?
See my journal for slashdot ID's by year. Mine created in 2005. http://slashdot.org/journal/289875/slashdot-ids-by-year
Sounds to me like the definition of "over-weight" is based on appearance instead of health.
Now I have an excuse to not lose those "extra pounds" my wife has been complaining about!
bringing the health industry profits since 1830
More calories or less?
http://en.wikipedia.org/wiki/Calorie_restriction
Calorie restriction refers to calories of food energy absorbed per day (rate of energy in). "Overweight" refers to accumulate body mass, in the form of fat (accumulation). You use fat at a rate determined by your physiology and physical activity (rate of energy out).
rate of energy in - rate of energy out = rate of accumulation
You can be fat and eat very few calories, or skinny and eat a lot of calories. If your rate in is equal to your rate out, you'll maintain your current weight, whatever that might be.
The study in TFA, however, is probably misleading to most of us because it's a critique of BMI, which only measures weight, not fat content. I know people who are very fit, not crazy body builders, and still considered overweight via BMI because they have too much muscle and not enough fat to match the index's expectations.
"I zero-index my hamsters" - Willtor (147206)
As someone who has been extremely underweight (body fat percentage down to 3.4%), 50 pounds overweight, and also a track runner in good shape, I can agree with this. Underweight is by FAR the worse: you feel absolutely horrible because your body doesn't have the nutrients you need to rebuild your body and keep it in good shape. It took me years to completely recover from that. There is nothing worse than waking up in the morning and feeling just as bad as when you went to bed because your body hasn't been able to repair itself in the night.
If you are the exact weight you need to be, then you need to have a very well balanced diet, that includes all the nutrients you need in the proper proportions. Otherwise, obviously, you are going to be missing a few nutrients you need.
If you are a little overweight, it's not nearly as hard to have a balanced diet: you can have a higher percentage of carbohydrates and lower percentage of protein in your diet and still be ok, because you are eating more than you need of both. It is more flexible and easier, even if less attractive.
And don't forget to eat broccoli. You're going to have to eat a lot of beef and wheat and other foods to make up for the nutrients you are not getting in green vegetables. That can put you far overweight, especially as you age.
Qxe4
And STDs are also incredibly rare too!
Taxation is legalized theft, no more, no less.
"70 percent more likely than people of normal weight to die" did they also find the fountain of youth? I'm pretty sure that humans have a 99.9999% chance of dying taking into account the humans currently alive who still have a chance of finding that fountain of youth. Its not the destination its the trip that truly matters.
I can see that the intent of the article will lead to immense amounts of false justification. See, the majority of people that are overweight usually arrive at that state from extended periods of poor eating habits (or lots of drinking), inactivity or a combination of both.
It also appears that both articles base their study largely on BMI, which is well-known for being an outdated indicator of health in relation to weight. It works for those that are not athletic or abnormal, but is unreliable for anyone in those two categories. What might have been a better criterion for this study was body fat, which correlates much better to a person's weight.
Intuitively, I agree with the point made here. From the little that I know about nutrition, I've read that having some extra weight (apart from lean body weight and the necessary amount of body fat) helps the body function much better in everyday situations. Should this reach mass media, I'm almost positive that this, amongst other things, will be the excuse for those that don't wish to consider improving their health and lifestyle choices.
Oh well. Mental masturbation never fails to relieve.
I'm sure you're feeling really smart now, having repeated the endless slashdot correlation does not prove causation meme. It's so great that every 14 year old slashdotter seems to know more about statistics than scientists do.
You're even closer to your "best of slashdot" award by not even reading the summary, or not knowing what "corrected for physical activity" means. But beware: the hundreds of "BMI is stupid because I'm not fat/It's all muscle/my bones are heavy" commenters are on your heels. It's surprising that there's not a single really overweight person commenting here, considering that 90% of overweight (by BMI) are simply fat. But maybe, just maybe, all the geeks here are secret superheros.
Fleur de Sel
"They" say being slightly overweight leads to a longer life than "normal" weight. Perhaps the reality is "they've" defined normal a little too low.
BMI also assumes your height is what you "should" be. I have scoliosis to a fair degree, so I'm about and inch or two shorter than I would be without it. How does this skew my BMI results? Some quick checks with online BMI calculators shows that adding one inch removes almost a point from my BMI. Which number is more accurate?
I'm not going to say BMI is a horrible thing, but as a critical data point in a study like this it is far too inaccurate. Body fat percentage seems like a much better factor.
That kind of survival statistic is always measured within some specified period of time, usually a year for this kind of study. So if, say, the annual death rate is 100 per 10,000 for people of normal weight (just pulling the number off the top of my head here), 170 per 10,000 for underweight people, and 136 per 10,000 for obese people, then the statement is correct.
The correlation between ignorance of statistics and using "correlation is not causation" as an argument is close to 1.
As long as you had food, water, and pr0n you could live forever on your computer chair.
Yeah, if you like bedsores on your ass!
;)
There aren't enough details to decide but I could understand how being slightly overweight could be beneficial to women in particular. There's a reason why women like these and this were considered the most attractive in antiquity. Chubby is coming back in style
Even today many guys like me prefer chubby women - they're softer to cuddle with, they tend to have bigger and more plump breasts, they're curvature is accentuated and their plumpness makes them look "cuter", they're better-equipped to have healthy babies, and (in my experience) they have more orgasms. The homos out there are aware of the popularity of "bears".
I'm glad that the starving, anorexic "heroin-chic" fad is going out the door. One can be fit and comfortable without having to go hungry or be unattractively obese. Vanity, like eating, is unattractive in excess.
It's not that bad. The igloo I grew up in, in Edmonton, worked pretty good at insulating us against the cold.
I remember coming in off the ice-flow, after spending the day hunting sea-lions for food and fuel-oil, the igloo was so warm I had to pretty much strip off all my clothing.
But now that I've moved to Vancouver, where we've got these new-fangled things called 'houses', I find that I'm expected to remain mostly clothed both indoors and out. And my snowmobile only is useful a couple days a year.
Sleep your way to a whiter smile...date a dentist!
You're being a bit flame-batish, but I do have to agree. The "fashion industry" (or rather what a bunch of homosexual men and weird women) promotes a form of female beauty that's largely at odds with the ideal as found throughout most of human history.
A few months ago my wife and I were watching Some Like It Hot, and during the scene where Marilyn Munroe sings, my wife commented that according to modern fashions, she would be considered overweight, if not outright fat. It struck me right there that here is one of the most sensual women of the modern era in one of the sexiest scenes ever to be found in the movies (all praise Billy Wilder with putting up with her to make this film), and a pack of queers and freeky fashionistas have programmed into so many that having some seventeen year old girl with the figure of an eight year old boy is superior to the greatest sex goddess of modern times.
So, from all the guys who secretly fantasize about the golden age of Hollywood sexpots, here's a big "fuck you" to the fashion industry, truly the most perverse and vile aspect of modern media around.
The world's burning. Moped Jesus spotted on I50. Details at 11.
...or is it just that it takes longer for friends and family of the slightly overweight people to realize the fact they are still on the couch is not normal.
"There is more worth loving than we have strength to love." - Brian Jay Stanley
That used to be true. Just look at anyone born before the early 20th century. 100% mortality rate. But with the rise of modern science and the marked decrease in pirates, we've slowly been reducing that rate.
If you look just at the stats for people born since 1980, you'll find a remarkable level of resistance to death, with death rates less than half of those who were born in the 1930's, so it's obvious that there have been significant improvements.
At this rate, not only will those born after 2030 never die, but by 2080, people will be living two, maybe even three lives at once, for eternity!
Last post!
The ignorance of some humor is just shocking!
Of course Canadians have cars and central heating. How else would they get to and stay warm in their yurts? Although the heating is a tricky business for those who live in igloos, but they're just a smaller portion of the population. Only about 35% or so.
The article mentions that they "controlled" for physical activity. Does that mean that they compared like for like? Fat couch potatoes with skinny ones, fat joggers with skinny ones? I'm not a statistician but it seems on the face of it there's a problem: Being overweight generally causes you to become less physically active, so comparing normal joggers to heavy joggers is comparing someone of high-normal fitness to an obese person who's extraordinarily fit (for their weight range). The comparison may not be fair because that extraordinarily fit person could have good genes to begin with.
That aside, people who are skinny are sometimes skinny for health related reasons: cancer, AIDS, drugs. Here it's not the fact that they're skinny which is the issue but their low weight is a symptom of health problems. A more complex take on that would be a person who has lost weight because they were ordered to by their doctor. They're diabetic or have high blood pressure. So yes, they've lost weight and are healthier than before, but still less healthy than the slightly overweight person whose doctor didn't make them lose weight because they didn't have metabolic syndrome. Again, the low weight would not be a cause of illness, but an (indirect) effect.
Also, if it's true that you tend to gain weight every year you remain alive, then people who live a long time are more likely to be overweight. Not because they're heavy but because they're still alive. And people who die prematurely young are more likely to be skinny, not because they're malnourished, but because they simply didn't live long enough for a slow metabolism to pack on the pounds.
There are two kinds of people: 1) those who start arrays with one and 1) those who start them with zero.
Sure, you'll be fine if you spend your entire life indoors. Which I'm guessing is what you'd do anyway, being on /.
You are welcome on my lawn.
BMI is like judging the value of a diamond on carat weight only. Much more goes into it than that.
Take for example, me. According to the typical categories, at 6'2", my normal range is 144lbs - 195lbs. Now, I'd love for you to look at a 6'2" guy that weight 144 and tell me he's normal (implicitly healthy) in weight. I have cancer patients that weigh more than that. And plenty of in shape guys that are 6'2" weigh well over 195. Science light...go America (and, apparently Canada).
BMI Categories:
Underweight = 18.5
Normal weight = 18.5-24.9
Overweight = 25-29.9
Obesity = BMI of 30 or greater
The other thing to be careful about with these statistics is that Canada has a very good public health system. One that far outranks just about every other western country on this blue marble. That will surely shift the results to the right compared to other countries.
And yes, I am dirty about it. My country *used* to have a superior public health care system. That is until a prime minister thought it would be a good idea to follow the US. There's the lingering shell but that'll be gone in a couple of years.
*sigh*
.
And how do you know which is which? The BMI is not meant to be used in the fashion that you're suggesting, percent body fat is. While percent body fat isn't the end all be all, it is a fair measure, and it does a pretty damn fine job of it too.
Unfortunately neither one does a good job of separating visceral fat from subcutaneous fat, and that's more important than being a bit chubby. I do carry a fair bit of fat, but very little of it is visceral, and I'm still within about 5lbs of what's ideal for a person of my build.
The BMI demanded weight of about 170 would definitely be detrimental to my health. BTW, last time I weighed myself I was roughly 189 and 5' 10.5, I don't feel well when I have gotten down under 180.
I used to concur with you that it is homosexual men pushing the "heroin chic" look, but a little more in depth look is revealing. Yes, skinny is the most noticeable aspect of the look, but there are other telling features involved with the supposed ideal body. Slight build, large eyes, androgynous features, lack of body hair... that describes a pre-pubescent child.
I'll never make that mistake again, reading the experts' opinions. - Feynman
There's a big problem with the BMI. It's a quadratic aproximation to a cubic mesure. I.e. the body should be proportional to the cube of the height.
No, it most certainly shouldn't.
Cube square law.
Large humans cannot be scale models of small humans. Bone strength is proportional to the square of the linear dimension, not the cube. If you scale the skeleton up by a factor of X, the mass you hang on it had better scale up by no more than X^2. Check out Haldane's essay "On Being the Right Size"
http://www.geoffreylandis.com
That's nonsense.
Everyone dies.
When your research indicated that overweight people live longer, what it's really telling you is that your definition of "overweight" is broken. And BMI is, indeed, seriously broken, since it does not take in to account age, build, or even sex. BMI says that a man and a woman of the same height should be the same weight. Which is medically dangerous quackery.
The BMI formula was created by a mathematician, not a doctor or someone with medical training. It was pushed as a medical standard by phamracuetical companies that have invested heavily in weight loss drugs. When they found that the 1985 standards for obesity (~27.5) wasn't selling enough weight loss prescriptions, they pushed to lower the threshold to 25 instead.
The reason there are more overweight Americans in the last ten years is that the definition of overweight was changed in 1998. You'll never see a news article that says "Americans used to average ### pounds in weight, and now they average ###+n pounds, or even that the average BMI used to be ## and is now ##+n. All you'll ever see is "there are more overweight americans, with no explanation of how this is determined.
Because, dammit! those pharmaceutical execs have boat payments to make!
what you describe as the ideal curvaceous woman is a man's idea of an attractive woman. a woman's idea of an attractive woman is not the same as a man's idea of an attractive woman. for whatever reason, a lot of women are very self-loathing. and no, its not the usual bogeyman we try to blame for our own behavior, "the media", its some sort of innate psychological thing. a lot of women really think the body of a prepubescent boy is the ideal female appearance for some reason
if you take a woman with a banging bod, subject her to constant attention from all men, she can still go home and look in the mirror and find something to criticize. and she does: she think's she's too fat
the fashion industry has no real power. the fashion industry is given power by the people who buy clothes: women. and there's a lot of self-loathing in the female world. a shame
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
Not so fast. As a guy who has married into a Canadian family (hailing from Vancouver, to be specific), I have had quite a re-education as to how bad the Canadian Health Care system is. I, like many other Americans, bought into the idea of how great Canada's Health Care System was, but I have been taught that this is absolutely not the case. I've learned this from many family members and friends. I've read many articles and stories like this one that paint a very different picture than the rosy one I had heard about before.
The bigger the cushion, the sweeter the pushin'.
No wait... That was Spinal Tap.
If I were God, wouldn't I protect my churches from acts of me?
1. This is old news.
2. They mean 20-30 lbs. overweight, not 100. I.e. the peak of the longevity Bell curve is about 20-40 pounds more than the supposed medically desirable weight. Then it goes back down again.
The guy giving the South Park kids a run for their money on WoW has a life expectancy significantly lower than the "normal" weight people, who are lower than the "overweight but not obese" people.
Cartman, however, remains doomed.
(-1: Post disagrees with my already-settled worldview) is not a valid mod option.
I would say everyone is 100% likely to die.
Speak for yourself. I plan on living forever.
So far, so good!
I remember reading a study like this something like 2 years ago. I don't think this is a new idea at all. As I recall, the conclusion of the one I read a while back was that people who are a little bit overweight tend to exercise more frequently than people who are at a normal weight in an effort to lose the extra weight, and the extra exercise gave them bonus health points. Basically, by constantly wanting to lose that extra 10 lbs, you improve your cardiovascular health in a way that far outweighs the negative impacts of carrying an extra 10 lbs.
It makes sense to me that people who are obese don't see the same advantages, because I imagine there is very little interest or incentive in getting out to exercise when you have such a long road to fitness in front of you. It also makes sense for obvious reasons that people who are naturally underweight or at a normal weight have less social pressure to get out and exercise.
Anyway, there's more to the "but it's Canada" argument than just heat.
Japan tops the world in longevity and they also have some of the lightest people in the world. While obesity isn't unheard of there, and neither is being slightly overweight, it's a lot more common to be underweight by the accepted western definition. I couldn't find the average weight for adults, but the average weight for a 16 year old male in Japan is around 136 pounds at a height of around 5'6". In the United States, that is the lowest recommended weight even for someone with a "small frame" at that height.
So why do they have such long lifespans if being slightly overweight is better than being underweight?
I'm sure it has mostly to do with the amount and type of nutrients a person is ingesting. Westerners eat a diet that's higher in fat and calories per nutrient. For example, they eat a lot more fish than we do; we eat more red meat. They eat more rice; we eat more potatoes. Without making a real effort or taking supplements, a westerner will need to ingest more calories and fat to get the same nutrients as a Japanese person.
I would strongly suspect that this is a case where correlation != causation in terms of being slightly overweight and living longer. A person would probably live longer still if they were slightly underweight but got the same (or better) nutrients, which is basically the situation in Japan and that is exactly the result.
I'll forego using mod points on this thread to reply. I'll burn them off on some other topic.
It's surprising that there's not a single really overweight person commenting here, considering that 90% of overweight (by BMI) are simply fat.
I qualify by BMI (29.5, just shy of "obese") and by personal assessment (yes, I do look feel fat in this body right now). I was forced into a more sedentary life style 20 years ago and for many years I was obese by any standard, but I've shed more than 20 lbs from my heaviest weight. I am now reasonably fit, bicycling over 100 miles per week and self-training to do century ride in a month or so. I also do flat water kayaking, which is a good complement to the biking.
link to the NIH BMI Calculator used below.
Here's the thing: my personal ideal body weight will give me a BMI of 27.0 at the weight where I felt best before the accident that changed a lot of things in my life. This is still "overweight" by accepted standards. But to get to the top of the "normal" BMI range at 25.0, I would have drop to my weight when I graduated from high school, when I was a skinny guy with all the muscle tone of a boiled noodle. My long term (5 - 10 year) goal is to drop another 20 lbs to a BMI of 27, but I would have to drop 33 lb to get down to a BMI of 25, and that would definitely be unhealthy.
BMI can be sort of helpful to people of European and Asian descent in possibly refining their personal ideal self-image, but it isn't going to work so well with descendants of Native Americans, Polynesians, or Arctic peoples. But it isn't very accurate, and if it does not match up with a healthy person's ideal self-image, it should be ignored.
Will
It's surprising that there's not a single really overweight person commenting here, considering that 90% of overweight (by BMI) are simply fat.
Since you asked: I'm really overweight; BMI is bullshit. These two things are not related.
The idea that body shape is irrelevant in determining "ideal" weight is somewhat bizarre.
By the way, great job coming up with that 90% figure - it's fun to make shit up, isn't it?
sic transit gloria mundi
So let me get this straight... your message to a "pack of queers" is "fuck you". Interesting choice of words. Something tells me that you spend a lot of time in airport bathrooms, tap tap tappin' away...
The thing is, I totally agree with your point. The fashion industry has promoted an unhealthy ideal for decades. So why did you have to ruin your post with the homophobia? I'm not doubting that there are tons of gays in fashion, I'm just saying that it's a huge homophobic leap to go from that to "teh homogays made wimmen hate themselves".
The guy who discovered Twiggy, the stick-figure prototype of the modern model, was hetero enough to have two kids with her. I know that doesn't prove anything, but still... are you sure that you're not full of shit?
I think you're dying to wear your Peter Pan costume to work tomorrow. And you know what? I hope one day you do give yourself permission to be who you really are. I'll support you in that!
There's an even chance that this will either shift the ideal range of BMI or place more emphasis on factors other than BMI. Maybe both.
BMI is a stupid measure. IIRC, it was developed in the 1830's for some kind of sociology study, nothing to do with health, diet, etc.
Penn & Teller's BullSh*t has a good episode called "The Obesity Epidemic is Bullshit", which is currently on Netflix streaming. They make the point that Brad Pitt is overweight and George Clooney is obese, according to BMI. And this is what they base our insurance premiums on....
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
... showed a similar result, until they controlled for for that.
Teetotalers were on average somewhat more likely to die than people who had a few drinks each week. Sounds like the same thing. Until someone realized that there were two subgroups of teetotalers: lifetime teetotalers and former alcoholics. The former alcoholics had a history of drinking a lot, but currently drank nothing. When they split those two groups apart, the lifetime teetotalers were the healthiest group.
I'd bet that the same thing will eventually be found here. There are two subgroups within the normal weight group: those who have always been healthy as distinct from those who have 'normal' BMI because they have some other health problem that affected their weight
Is accurate geography really important in a satirical take on uninformed stereotypes?
Canadians love to complain about our health care system, but the numbers show that it does very well compared to other systems.
The article you link to seems pretty shady. It's clearly looking for reasons why the US should not change their private health insurance model. The first paragraph talks about how Erbitux (cetuximab) "... targets cancer cells exclusively, unlike conventional chemotherapies that more crudely kill all fast-growing cells in the body" even though standard treatment with cetuximab is used in conjunction with chemotherapy and/or radiation therapy, in patients who do not respond to chemotherapy alone. Did she already fail a course of chemotherapy? She went to a cancer clinic in a foreign country (the US) and was surprised that it was hard to get reimbursed? Finally, cetuximab is only used in cases of colorectal cancer where there's EGFR expression. If her tumor was not this kind then treating her with cetuximab would indeed be unproven. It also appears that cetuximab has not yet completed it's phase III trials, which again makes it experimental. Nevertheless, it has been approved by Health Canada for patients who meet the criteria above.
You can read the Health Canada Summary Basis of Decision on cetuximab here: http://www.hc-sc.gc.ca/dhp-mps/prodpharma/sbd-smd/phase1-decision/drug-med/sbd_smd_2007_erbitux_088225-eng.php
Well, I have a fun anecdote for you.
A month ago I thought exactly the same thing that you do: just because you're eating fat doesn't mean it sticks to you. ...and, actually, that's still true. It's more complicated than that.
Months ago I came across this news item:
http://www.eurekalert.org/pub_releases/2009-01/cp-adr122908.php
I read the article that the scientists wrote in Cell Metabolism (it was actually free at the time, but not anymore), which was nice and scientific and all. They took some mice, fed them a high fat diet, waited for them to become obese, then did some tests to determine if the cellular stress they suspected of causing obesity had occured. Then they gave the mice some drugs to reduce this cellular stress and, like magic, they began eating less and exercising more and lost a lot of weight, all of their own free will. (Naturally they used a lot of control groups, but I'm just summarizing.) It was nice to see that real scientists were working on the weight loss problem, given that the weight loss industry is all about pointless bullshit.
Anyway, after tiring of eating mostly oatmeal cream pies, I switched to a diet of ice cream for about a week, at which point I randomly weighed myself and found that I weighed 260 pounds, which was up from the rather steady 250-255 I had seen for the past year. I was sick of ice cream by that point anyway, so I went to the store and picked up some Stouffers heat-it-in-a-pan meals, for no reason other than that they looked good.
While cooking the stuff, I noticed the fat content was really low. Eating an entire bag was only 25% of the recommended fat intake. This made me start thinking about that study those scientists did, and how, while they seemed to carefully consider all sorts of variables, something they seemingly assumed to be an absolute truth was that the path to obesity was a high-fat diet. In fact it seemed to be their theory that the high fat diet causes some sort of stress in the leptin-sensing cells in the brain, causing the brain to believe the body has less fat than it actually does.
Thinking about it, if it were true that high fat diets cause obesity, it would be the simplest experiment to confirm it. Get some mice, feed one group a high-fat diet, the other a low-fat diet, let both groups eat as much as they like, and see what happens. Surely if it weren't true, scientists researching obesity would know.
This all got me thinking: Assuming I'm overweight because I've eaten high fat foods and reduced the leptin sensitivity in my brain, would eating a low fat diet allow that leptin sensitivity to restore itself? Since I had a week's worth of Stouffers meals anyway, I decided to find out.
I'd tried low-calorie diets before, but they never went anywhere. As I tell people all the time: Hunger is regulated by the brain. If you're not eating what it wants you to, you'll spend all day thinking about food. Despite popular belief, overweight people don't eat for the joy of it. I was eating only oatmeal pies because I simply couldn't convince myself to eat anything else, and I really didn't like the oatmeal pies all that much either. It was just that whenever hunger became uningnorable, it was easy to eat one and get back to whatever I was doing.
Even though the Stouffers meals were fewer calories than I was used to, I initially started out with just two bags a day, which is only 1500 calories or so, and yet I didn't really feel any need to eat more than that. I expected that after a day or two my brain would wise up to the fact that the same volume of food was now fewer calories, and cause me to want to eat more, but it didn't happen. I was sort of hungry, but it was the kind of hu
See, for example, http://www.jstage.jst.go.jp/article/jea/14/Supplement_I/14_S18/_article for a study in Journal of Epidemiology showing what I wrote. There are more.
If they did, I didn't see it in the article. The problem is that sometimes the causation factor runs the other way - being unhealthy causes you to lose weight. If you have, say, AIDS, tuberculosis, or certain cancers, the disease both causes body wasting, and makes you die sooner. This can skew the statistics - yes, these people are skinny and died younger than they should have, but the skinniness didn't cause the early death - instead, both were caused by the underlying disease. It's possible that if you controlled for that, that underweight people wouldn't show such a tendency to die young.