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Comment by bwestergard | Hacker News Reader

This paper provides a helpful breakdown of types of mortalities and how they're associated with BMI. It's interesting to see that the lowest All-cause mortality is at a BMI of 25. A BMI of 30 doesn't increase the hazard ratio that much, but a BMI of ~45 doubles it. The minimum for cancer mortality is notably lower (21) but perhaps surprisingly the minimum communicable disease mortality is at a BMI of 26.

https://www.thelancet.com/journals/landia/article/PIIS2213-8...

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This kind of stat is misleading and is seen in many health metrics - blood pressure, cholesterol, etc. In fact, it's sometimes known as the "cholesterol paradox" because people with higher cholesterol have a lower risk of dying. However, it's misleading because blood pressure, weight, and cholesterol often come down as people suffer from chronic disease or malnutrition. The chronic diseases people get are often from their weight, blood pressure and cholesterol, and when this is corrected for, the all-cause mortality curves better reflect what a healthy person's numbers should be. So in reality the lowest point of the all-cause mortality curve for BMI is below 25. 25 is not optimal.

Dr. Carvalho recently made a video on this topic (he even mentions the BMI curve). You can watch it here: https://www.youtube.com/watch?v=n4h135SBebc

Thats interesting because I am healthy in other ways but my cholestrol has been high ( high ldl, total and high apob) . My trigs, a1c, bmi, homa insulin score ect are in line. No history of heart disease in either side of family.

My cardiologist has been asking me to get on statins for a while but i've been not able to convince myself to get on board to take a pill for the rest of my life.

There's something called a "lean mass hyper responder", it's a type of person with high LDL but they're still healthy. You may fall into that category. However, high apob is more correlated to heart disease than high LDL. A lot of the online doctors who say high LDL isn't bad are saying that because some people have large LDL particles, and it's apparently the number of particles that's the problem, not the amount of LDL cholesterol.

I've dug into this topic a lot sense there's a lot of heart disease in my family. I've found that eating a bowl of oatmeal once a day reduces my LDL under 130 (I've been taking quarterly cholesterol blood tests to keep an eye on things). It's probably the fiber content that's doing the work, but I haven't tried other high fiber foods yet. However, I'm not a doctor so make of this what you will.

yeah APOB is what drove my doctor to give me a prescription for statin

My guess: less cells mean less cancer, but it's good to have reserves if you're fighting off a virus?

More likely relates to diet. There was a recent WashU study directly linking high fructose diets to increased cancer. Cancer cells are vigorously growing, needs lots of available fuel, a diet full of corn syrup fuels both fat and cancer.

> a diet full of corn syrup fuels both fat and cancer

Or sugar. Or modern fruits. The problem with HFCS isn't that it's got fructose (so does cane sugar) or is made from corn, it's that it's cheap sugar.

How much fruit do you have to eat before it becomes harmful? I can imagine juice can easily be over consumed but solid fruit is very satiating.

> How much fruit do you have to eat before it becomes harmful?

Unclear. The aforementioned study fed mice sugar water [1], and cautions against extending its findings to fruit as "natural fructose obtained from plants typically confers metabolic benefits due to its slower absorption rate and the presence of beneficial plant fiber and antioxidants."

It does mention, however, that "human physiology...confronts challenges when metabolizing fructose beyond 25g/day." That's like a cup of grapes, a medium pear or half a mango [2].

[1] https://www.ijbs.com/v20p3480.pdf

[2] https://www.webmd.com/diet/ss/slideshow-fruit-sugar

>solid fruit is very satiating.

Very briefly.

I've stopped eating fruit (and carrots, which have fruit-like levels of sugar) with the exception of tart (i.e., less sugary) cherries out of a desire to limit my fructose intake. I was eating raspberries, too, which are much lower in sugar than most fruit, but stopped because of their high levels of oxalic acid, but I do expect to restart raspberries in a few years because I expect my ability to tolerate oxalic acid in my diet to improve slowly over the next few years. (In contrast, high-fructose foods including most fruit are probably gone for good.)

Of course, I'm not asserting that everyone should do as I am doing. There is substantial variation between individuals here.

It's funny all the modern fruit I see is bigger but dry and not sweet at all

AIUI cancer cells are also metabolically inflexible; they like glucose, not ketones.

Good evidence for this found here: “Tripping over the Truth: The Metabolic Theory of Cancer”[0]

[0] https://www.goodreads.com/book/show/23496164

> AIUI cancer cells are also metabolically inflexible; they like glucose, not ketones

Is there a selection effect at play? As in, a person with high serum glucose levels will tend to have cancer that likes glucose? That would imply the solution isn't ketones per se, but changing the fuel from whatever the cancer grew up with.

iirc the talk I learned this from said there's simply not many cancer variants that don't need abundant glucose to grow tumors. That the whole defect stems from hijacking the energy side to fuel uncontrolled growth, and it needs glucose.

I know someone who tried to use keto to manage her bowel cancer, and died. Used to know rather than know I guess

Yeah I see this take all the time and it's dangerous, it might have an element of truth but it's definitely dangerously simplistic. You can find advocates of low fat high carb diets also claiming that very low fat intakes improve cancer survivability.

I'm sorry for your loss

You're absolutely right it's dangerous. It's likely that I gave myself cancer by adopting this 'simplistic truth'.

A decade ago I read about the keto diet and thought "why not?". Lots of positive stories about dropping weight fast, getting mental clarity and starving cancer.

A few years later, I was diagnosed with a rare Leukaemia (with a distinctive BRAF mutation). I was too young to have a cancer so I thought... maybe this keto thing is not so good after all?

Cue to several Pubmed rabbit holes, where I find studies suggesting that one of the ketones (acetoacetate) promotes tumor growth in BRAF-related cancers (melanoma, colorectal, hairy cell leukemia, and others).

Well, that was the moment I stopped doing stupid 'hacks' with my body and strictly adhere to the 'common sense diet' - ie eating like my grandpa did.

While I can't confirm 100% that my cancer was triggered by the keto diet, I have a strong suspicion it did. So yeah, before going online and stating grandiose things like "cancer starve on ketones, they need glucose" let's all acknowledge that we humans know very little about what's going on with cancer, and the potential adaptations it can do.

Some sources: https://pubmed.ncbi.nlm.nih.gov/28089569/ https://pubmed.ncbi.nlm.nih.gov/26145173/

It also doesn't pass the smell test for me because some of the most long-lived, relatively cancer-resistent populations like the Japanese eat carb based diets. That's hard to explain if it really is just a case of replacing glucose in the fuel mixture with fat and ketones.

+1 for the 'grandpa diet', I also feel best eating normally

Perhaps people getting cancer treatments tend to lose a lot of weight before dying?

Another possibility is that unexplained and unintended weight loss is associated with increased risk for many types of cancers.

The focus on kg/m2 (BMI) I cannot understand. Surely the lowly “body fat percentage” should be a better variable than kg/m2? Bodies are three dimensional you know!

It is much easier to measure, and is a good enough proxy for the vast majority of people.

To quantify, I've heard MDs say that the outliers (relatively high BMI but low body fat) constitute less than 1% of high BMI people. They also said that those outliers are still at risk of certain health troubles, like sleep apnea.

The suggestion of using BMI + waist circumference is an easier to measure risk factor than bodyfat percentage and helps to better capture those outliers.

I imagine the missing spatial dimensions are correlated with weight, for any given height.

BMI is trivial to measure conclusively, using tools that are almost universally available and ready. And at population scale, it's proven to be a strong and pretty signal for analyzing in studies like these as the ways in which BMI can fail for individuals is too uncommon for it to matter to population studies.

It's a perfect tool to use for studies like these, as it can contribute understanding society-level concerns about the obesity epidemic and what impact we can expect it to have if it continues not to be tackled.

But like with almost all medical and nutritional research, drawing conclusions for yourself as an individual based on these population-scale studies is inevitably fraught. In the case of BMI studies, you can often get a fair sense of whether you should be concerned or not, but do need to take into account other things that you know about your lifestyle and health. Your doctor, presumably, does exactly that.

Meanwhile, body fat percentage tends to be very hard to measure accurately in the first place and has different techniques that tend to have different error characteristics, making it hard to correlate it between studies done through different clinics, let alone against someone's personal assessment at home or with their personal doctor/trainer/whatever. It probably has high relevance to some medical and nutritional outcomes, but isn't a very useful input variable for research because its inescapably noisy.

I apologize if this is tangential, but I have noticed BMI research is often heavily criticized, but the same issues that plague BMI can easily be applied to psychometric measurements of intelligence (IQ), but somehow IQ is spared the same beating for some reason I must not understand.

Perhaps my low IQ is showing, but why is one metric heavily criticized while the other is not? (Rhetorical)

Huh? I haven’t seen “IQ” seriously used in decades. Its flaw are well known.

Even in popsci/social media I've seen more and more awareness that it's "bunk" science.

It's in the same category as all that "alpha male" theory, Meyers Briggs, polygraphs, and "left vs right brained" people.

I'm starting to see more awareness around the concerns of "ballistic forensics" too, which is heartening.

> Even in popsci/social media I've seen more and more awareness that it's "bunk" science.

Devil's Advocate: Then why is it so heavily used still? (Then again, I guess back to my initial point -- the same could be said for BMI.)

Proof that's it's still heavily used in serious scientific literature?

How do you define 'serious scientific literature?' In other words, what type of evidence would you like me to present? Does any peer reviewed research that uses IQ as a factor count as serious? (Obviously, I won't present research that is about IQ measurement.)

I have never had IQ test taken, but countless of times BMI has been calculated. Mind you I have had other mental tests done due to ADHD and Autism concerns, and some of them were similar about abstract logic, but they were combined with other things like focus, memory, multitasking, literary understanding and other mental capabilities. The results of these tests were presented as percentiles in the population.

Interesting. I was given an IQ test for ADHD diagnostic purposes. There were other test given, as well. And in my opinion, the other tests were more indicative than the IQ test was (which I think is falling out of favor with ADHD testing). Then again, there were some issues with my test and scoring, so it makes me even more dubious of the (psuedo)science.

I went through the arduous process merely for the formal documentation, which in hindsight has served me well. Not a single doctor has ever questioned my diagnosis. However, as the psych told me, a 10 minute conversation with me should honestly have been evidence enough. ;)

Interestingly, the actual ADHD tests didn't find any issues, my main issue was my mind wandering in social situations, listening, understanding, keeping track of conversations and my own input. But whatever the tests were they were stimulating enough that I had no problem focusing. It's also repetitive, routineus actions that I have trouble focusing on, so it's almost like untestable issues. I did get the diagnosis though, I don't remember with what justification since the tests didn't allow for that.

Do you mean "why is it still used in popsci"? I'd wager because it makes people feel a similar way to other pseudo scientific categorizations, but that's mostly speculation on my part. Add in a bit of inertia and the simplicity of it ("let's reduce the cognitive ability of people across the world to a single number!") and, to me, I can see the appeal for others.

I was administered the WAIS-IV for the purpose of a clinical diagnosis about 10 years ago. My state still considers it one of many factors in whether one is a candidate for the death penalty. Some gifted programs still accept the scores as necessary evidence for admission.

Army too, back then. IQ test and MBTI (Myers Briggs), if I recall correctly, then OCS considerations if ranked well enough, including an oral interview.

> somehow IQ is spared the same beating

I think this is the part you're getting wrong, which is why you're confused.

IQ was contentious from its introduction in the beginning of the 20th century, caught some traction in the mid-century, and has mostly been on a decline of esteem and respect again since. It's never been very broadly accepted, let alone spared from criticism, nor have most other psychometrics, although (as always) there are bubbles of academia, industry, and the general population that swear by them and work to legitimize them.

Kurt Danziger has published really great histories of all this.

I'll add that his books are especially interesting in the context of all the AI buzz as insight into the history of "intelligence" (the word, the socially constructed concept, etc) helps wrap one's head around what it means when people working in CS try to repurpose its terminology in their own field.

IQ is as far as I can tell quite well accepted as a diagnostic tool. The pushback is in its application across whole populations.

FWIW, anecdotal data is also considered a valid diagnostic tool too, and we know how unreliable such information can be.

Also, by populations, do you mean groups of particular types of people or just groups of people in general? If anything, I thought IQ really only had anything close to merit at large population levels. Much of what I have read clearly fails at an individual level.

However, if you are talking about IQ's application in regards to populations like one race vs. another, then yes, I think the pushback is well deserved.

I agree with you about your last statement! I think it's actually a pretty interesting comparable to BMI. BMI: useful epidemiologically, across large populations, but much less useful individually. IQ: much less useful across large populations, but useful as a diagnostic/clinical tool in individual settings.

> IQ is as far as I can tell quite well accepted as a diagnostic tool

Inside certain bubbles, sure, because there's pressing demand to have something quantifiable and sufficient supporters willing to assert its legitimacy.

But good luck taking your test results outside of those bubbles to earn you some opportunity or respect, even if you can say your test was administered to the highest standards by the most respected administrators.

Nobody here will take your results to mean anything. Nobody at your work will take your results to mean anything. The recruiter at some new potential job won't either. The prestigious university you want to attend won't care. Most of your partners and friends probably won't.

Many of them may already have a sense of whether you're "intelligent" or not, either from personal interactions or from other practical indications. But good luck finding somebody of material influence who would hear your IQ score results and change their mind. It just doesn't have that weight.

That's what it means for it not to be treated seriously outside of bubbles. There are supporters that back it, and there are institutions that rely on it, but outside of those very specific places, there's very very little trust in it.

In any bubble where IQ is considered legitimate, just mention that Richard Feynman apparently had a recorded IQ of 124 or so (or Lewis Terman's study of gifted children).

You'd think someone tried to convince those in the bubble that the Earth is flat. In my experiences, I have been met with all kinds of rebuttals like, "The test he took was probably over-weighted in verbal vs. spatial reasoning" or "He probably just blew the whole test off."

No one has a copy of the actual results to my knowledge, but he and his sister (who oddly enough scored higher) verified the story back in the day according to biographers. So, not telling what is the true story.

For the sake of argument, let's assume Feynman's score was indeed accurate. I think it makes people extremely uncomfortable for two reasons:

1. Some individuals with high IQs (IQ >= 130) feel threatened or ashamed by the fact that someone with an high but unremarkable score was capable of truly remarkable contributions to their field.

2. The scores are truly not always accurate or might potentially measure something that isn't intelligence.

If Feynman's score was indeed an inaccurate measurement of his intelligence, then that says more than I need to know about IQ testing.

I mention Feynman because I am in agreement with you:

> Many of them may already have a sense of whether you're "intelligent" or not, either from personal interactions or from other practical indications.

No one would consider Feynman to be unintelligent by any stretch of the imagination. However, at the end of the day, his score truly doesn't matter. Feynman nor anyone else is not remembered because of their intelligence, but rather, his contributions. Besides, exceptional people tend to be, well, exceptional.

> IQ is as far as I can tell quite well accepted as a diagnostic tool.

not at a scientific level, no

Are you sure about that? I'm shoplifting an argument from Twitter from a quantitative psychologist.

The pushback is because it suggests some uncomfortable possibilities...

Also wait until people find out the correlation between IQ and obesity (runs for cover)...

> there are bubbles of academia, industry, and the general population that swear by them and work to legitimize them.

Perhaps you a right, because this is my main exposure to psychometric. From much of what I have read from various journals, there are clearly those that are contrarians, but mainstream academic psychology presents IQ as if IQ is some infallible measurement of human intelligence.

Despite IQ's merits being contentious (like BMI), it is still widely used regardless. IQ testing is still used for clinical diagnostic purposes (why I had to take one), entrance in to some gifted academic programs, in judicial contexts, etc..

Based on my personal research and experiences, I align with the contrarian views vs. the mainstream, academic views.

IQ routinely gets destroyed. As an example, I was an undergraduate in the 1990s. My statistics class skewered the use of IQ back then. According to some friends with undergraduates, they still use that as an example of statistics being used badly.

People say that, but then people like me are administered the tests for clinical diagnostic purposes (right or wrong), and even my state still considers the scores to be a valid measurement of intelligence, and thus a factor in whether someone convicted of murder is eligible for the death penalty.

I think the concept is bullshit myself, but regardless the damage is done, and still being done for what it is worth.

My crude understanding is, we don't have a good way to calibrate above-average scores, but it is a good measure for below average (provided there aren't arbitrary barriers like the language it's in).

That’s too bad, but I replied to something that claimed there is no criticism of IQ. IQ is criticized and used. Those are not exclusive states.

Yup. Polygraphs are still used in the intelligence community and court too.

I'm seeing the tide turn (imo), but by no means am I claiming it's no longer used (regardless of merit). I acknowledge I'm starting a personal anecdote which is subject to my own biases such as cohort affects.

IQ is an interesting one. There are indeed plenty of issues in actually measuring it and deciding what we're even measuring to begin with, but at the same time, I've heard some people try to say it doesn't even exist at all.

Which seems odd, because I've yet to see anyone who doesn't believe that stupidity exists and it's the other side of the same coin.

> I've yet to see anyone who doesn't believe that stupidity exists and it's the other side of the same coin.

I do not think that is the argument though. Clearly, there is some sort of distribution of all human attributes. I think the argument is in how (in)accurately something as qualitative and arbitrary as intelligence can be measured.

I like the analogy of athleticism. Some people are more athletic than others, but again, such differences are generally highly contextual. I am sure some sort of test composed of factors like the number of push-ups, sit-ups, and time trial of a 100m dash could be used to generate some sort of AQ (athletic quotient).

However, scoring high on the 100m dash might positively correlate with performance in sports, but I would not wager that a high AQ is truly indicative of athletic performance as a whole. At least not in any transitive sense when mapped to many sports. For example, Usain Bolt might have a very high AQ because of his running ability, but his AQ might not serve him well in a game of ice hockey or swimming.

Sure, but in the case of a hypothetical AQ, we could do factor analysis and pull out different things, like the strength of various muscles or muscle groups, like all pure running tests had strong correlation with things like leg muscles. In IQ, this has famously been done and found that a single factor dominates.

Or when they saw that knowledge of arcane sport rules interfered, they could look for a more pure test of ability rather than knowledge, which they did with IQ by going from tests of specific factual knowledge to Raven's progressive matrices.

And when you do that kind of work, you find that you can develop better measures that have a lot of predictive power for whole populations, even if they do not tell you, say, how many goals they'll score in their next hockey game.

IQ is definitely not spared. It doesn't take a Mensa member to realize that human intelligence cannot be reduced to a single number.

> BMI is trivial to measure conclusively

That does not make BMI a good measure.

It does for some applications, and not for others. In epidemiology you're looking at the number across broad populations, where a lot of the "three dimensions" idiosyncrasies cancel out. You're likely to run into trouble taking literal BMI constants and turning them into individualized patient care instructions, though.

Or basically: there are outliers, and those tend to complain. But the average billions cancel them out statistically.

I'm an outlier myself, and so is anyone who did some serious sports for a significant amount of time. There are other reasons to be an outlier too. But they're not so statistically significant.

ditto. Always a bit frustrating when the sadly overweight nurse looks at my height and weight, charts it, and mutters to themselves "borderline". My last visit, at least the doctor deigned to actually eyeball me and said "you look like you are quite active, we can ignore this".

Oh I'm inarguably overweight, but not to the point the BMI would indicate, considering that when i was younger and in top form i was between 29 and 30.

You are saying it is a not dreadful statistical measure.

That is doubtful, but possible

It is used for individuals. That is where it is harmful

> harmful

It's hard to conceive of anyone meaningfully "harmed" by being a BMI outlier.

The only real occassion it comes up is when some lean and uncommonly athletic person gets miscategorized as obese and get warned of increased risks to their wellness if they don't lose weight. A warning which they generally laugh at because they know their own situation.

That's hardly "harm" -- "mild social nuisance" is more apt.

> It's hard to conceive of anyone meaningfully "harmed" by being a BMI outlier.

"You are fat. You must diet."...."Oh my Dog!! I am fat!!! I will fast"

Potentially for health insurance but I get the actuarial argument, especially since higher than typical weight regardless of fat composition puts higher than typical strain on your cardiovascular (and other) systems

The harm is that are more likely to get prescribed unnecessary medications. Most people are not confident enough or not knowledgeable enough to wave off what doctors say.

It's an easier diagnostic metric. Being jacked shit house with high BMI will still suffer from health issues of merely being overweight relative to frame.

> Being jacked shit house with high BMI will still suffer from health issues of merely being overweight relative to frame.

Do you have evidence for this? (Assuming getting jacked without the use of steroids)

Well, for one, it places the same strain on the skeleton, with all the consequences that entails. Mass is mass, no matter if it's muscle or fat.

Well yes and no. Strain on the skeleton from excess muscle isn't particularly a problem unless someone is really huge or does a lot of running. The skeleton adapts to handle the load. Having more strength in the muscles that stabilize joints actually reduces the risk of joint injuries — up to a point.

https://peterattiamd.com/belindabeck/

The medical problems with excess muscle mass tend to be more on the cardiovascular system than the skeleton. And the process of gaining a lot of muscle mass can increase the risk of musculoskeletal injuries (especially if using PEDS), which is a key confounding factor when looking at population health statistics.

Wouldn't some (if not all) of that be mitigated by the increase in bone density that comes with resistance training?

The problem is not bone density. Your bones are never going to break under your own weight unless there's something seriously wrong with you. The problem is joint health.

Sure, guess I read your comment as bone-focused. That said, joints also do get more resilient when resistance training. Although, I'm aware not necessarily at the same rate as the muscles themselves, leading to issues where the muscles are capable of handling more weight than the joints can happily handle (if we are to personify joints). But, I think that issue is mostly obviated with good programming and load management.

Your heart is still moving the same weight, fat or muscle. It's the same from system stress. Experiencing more health issues from bulking even at >20 bodyfat is pretty common... blood pressure etc. At some point just being a bigger person who has to eat more takes a toll.

An example is sleep apnea, which is highly correlated with neck circumference and being “jacked” can often mean your neck grows as well. There are many “jacked” amateur and professional athletes who suffer from sleep apnea. (Something like 30% of American football and rugby players have sleep apnea.) There are a myriad of negative risks associated with it, from cardiovascular risks to dementia.

BMI is more of a screening metric than a diagnostic metric. It's not really diagnostic of any medical condition beyond obesity itself, but if a patient is outside the normal BMI range then that can be a reason to justify additional diagnostic tests for certain conditions.

While there are potential health issues (outside those resulting from PED use) to being too jacked, they're not even remotely the same severity/risk as those from carrying too much body fat.

Let's put it like this: the probability of an individual to be at a BMI of 30+ AND being very lean, while not using PEDs, is extremely low. So low, in fact, that it doesn't make sense to even look into these outliers from the societal health point of view.

Imagine a 180cm 98kg male. That would be a BMI of 30. How often do you see people of that size with visible abs? And of those, how many are the ones who've never touched steroids, sarms, peptides and hgh?

If a person's BMI is less than 30, they are going to be okay no matter what their body composition, and with a BMI of 30+ they aren't going to be okay, whether they are fat or jacked. Both obese and insanely built people put massive strain on their knees and back, both typically have high blood pressure.

Then the adipose tissue itself has various negative inflammatory effects on health, which sceletal muscle doesn't, and fat people encounter psychological side-effects of being unattractive, which jacked people don't, but PED use has its own list of well-known issues, and being THAT MUCH into bodybuilding is highly correlated with body dysmorphia alongside other physch issues.

So both are bad, and when speaking about general population health, we shouldn't really focus on body composition- BMI is good enough marker on its own

4 years ago I was 100kg @ 185cm. Never touched PEDs. All it took was being in the gym going all out for around 2 hours, 6 days a week. My body fat was 13% consistently. I tried going below 13% until it started to affect my strength.

The rest of my life also revolved around recovery and nutrition because very quickly I realized that I needed to make extraordinary efforts to allow my body to recover from the regimen. I slept 10+ hours and ate around 3300 cals daily (TDEE was massive).

Being on antidepressants at the time made eating these amounts much easier, as it seemed to turn off something in my brain responsible for me feeling satiated.

I started gym after being diagnosed with the psych issues. I really put 110% effort into it and got… big stretch marks because my muscles grew so fast. I don’t think what I was doing was ”healthy” as much as it was ”I am super depressed and heavy barbell squats is my coping mechanism”.

I just wanted to say, you don’t need PEDs to get ”scary” jacked. But you probably need to be crazy like me.

If (and that is a big if. Most people severely underestimate their body fat levels. And with some touting 3% dexa scan results, even such measurements are suspect) you really were at a bmi of 29 (which, BTW, doesn't count as 30+ from my original statement ), then congrats on your amazing genetics and work ethic.

Still, to break that bmi 30 barrier significantly, while maintaining the same level of leanness, you'd likely require some additional 'help'.

And again - it is possible for a number of gifted people, just highly unlikely. Most males can't get that jacked no matter how much and how hard they train. I'd say that even with PEDs most wouldn't break that barrier while staying lean.

My personal best was a 28 bmi with what looked like a 9% body fat, veins fully visible at the lower abs and the hips etc, and it was absolutely unsustainable for more than a year, for a plethora of reasons. Can't even imagine gaining 3 more points.

To reiterate: I'd still focus on a BMI to gauge the public health - the genetic outliers are rare

If you are not an ELITE athlete or bodybuilder... then BMI is accurate. You are coping.

I'm just big boned.

You yourself are coping about the inaccuracy of BMI, what is so hard to accept that BMI is a sucky measurement?

[flagged]

What is so hard to accept that BMI is a good measurement?

Imbecile.

Outside of elite athletes, BMI is good at what it’s for. It’s just an easy way to express the relationship between your weight and height. Everything else requires specialized tools and contains a large margin of error.

BMI (as a diagnostic tool for overweight and obesity) has some problems, but it's good enough for most people most of the time. The measurement is FAR less likely to return a false positive (due to someone being "too jacked") than it is to correctly identify some who is carrying too much body fat. In any case, BMI plus a waist circumference measurement is even more accurate, and is still an easy, accessible and useful clinical diagnostic measurement.

Not really, because you can have low body fat and low muscle and be an absolute mess

kg/m2 is akin to height and width which is 3 dimensional

This particular statistic has a ton of problems. It's impossible to disassociate the various causative pathways that land you at a BMI below 25. A ton of them involve diseases and chronic conditions.

Unfortunately, it's very hard to impossible to RCT this. And if a study has no RCT, take it with as much salt as your diet allows.

You definitely don't want to intentionally gain weight on the basis of this. If weight control is easy for you, I would personally strive for a lower BMI.

If losing weight below 25 is hard for you and your body just seems to refuse to do it, then you might be OK at 25.

What's RCT?

Randomized controlled trial.

Roller Coaster Tycoon

> This particular statistic has a ton of problems. It's impossible to disassociate the various causative pathways that land you at a BMI below 25. A ton of them involve diseases and chronic conditions.

I'd beware of using this sort of hand-waving to ignore the studies, there are also effects pushing the relationship between average health outcomes and BMI in the other direction. Your ethnic origin seems to be very important, and for ethnicities who already have a high propensity for Type 2 diabetes, higher BMI is a factor, but not a huge one.

> Strikingly, in those with a normal weight, the prevalence of diabetes was 5.0% in whites, 10.1% in Asians and American Indians/Alaskan Natives, 13.0% in Hispanics, 13.5% in Blacks, and 18.0% in Hawaiians/Pacific Islanders.

> Furthermore, when they examined the relative risks for diabetes for each BMI category by race/ethnicity, Zhu et al. reported that across all racial/ethnic groups whites had the steepest BMI gradient, followed by Asians, American Indians/Alaskan Natives, Hispanics, Hawaiians/Pacific Islanders, and blacks.

https://diabetesjournals.org/care/article/42/12/2164/36251/D...

Another potential distortion comes out of this when you consider that black and Hispanic people are the fattest in the US. Blacks and Hispanics can have lower lifespans for reasons other than BMI, such as access to health care, high-quality food, exposure to violence, physical jobs, etc...

So just these two factors complicate the picture in general (your fattest have the least access to health care and most exposure to danger and neglect), and and in the other direction specifically for white people (an increase of BMI in white people makes a huge difference in their incidence of diabetes.)

Anecdotally, I'm black, and there's a lot of thin diabetes in my family. My dad usually runs about 20-21 BMI, and is pre-diabetic. His mother, who is also small, though not quite as small, is also diabetic. As far as I can tell, the fatter people in both sides of my family are no more likely to be diabetic than the thinner ones.

Not the original commenter, but pointing out problems and complexities is not hand-waving. Nutrition science is incredibly complex. If it wasn't, obesity would be solved by now.

> Another potential distortion comes out of this when you consider that black and Hispanic people are the fattest in the US. Blacks and Hispanics can have lower lifespans for reasons other than BMI, such as access to health care, high-quality food, exposure to violence, physical jobs, etc...

Okay, but this study is from Australia, on Australians.

Yet another showing "overweight but not obese" might not actually be bad, and this post's title is wrong?

("Overweight" is the BMI range 25 - 30, "obese" is 30+)

Being overweight increases the risk of developing quality of life reducing conditions and that is bad (it’s not being overweight itself that is bad). This is the case even if it doesn’t lead directly to dying. I would be careful about pushing the narrative that being overweight but not obese is just fine just because it won’t significantly increase your chance of straight up dying. Type 2 diabetes is a treatable condition so might not lead to a significant increase in deaths, but not exactly something you would want to develop if you can avoid it. And your chance of developing just that does increase if you are overweight even if you are not obese.

I'd like to emphasize the "might not": The impression I get from all these studies (I've seen them pop up pretty regularly for as long as I've been paying attention, nearly two decades) is that the border is actually wrong, that going from "normal" to "overweight" should be increased slightly from 25 to 27 or so. We're probably getting mixed signals in the "overweight" classification because "okay" and "bad" levels are being combined.

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