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Comment by SamPatt | Hacker News Reader

Some interesting points in here, but the author seems to imply that the obesity epidemic is really just in our minds.

I don't buy that part at all.

Yeah, I disagree with that part as well. Most people don't look like actors, a lot of people are very overweight and out of shape.

It's weird that all movies seem to play in a parallel universe where everyone looks like the fittest people ever.

Another jarring thing is movie people don’t stare at a phone every waking hour.

Films really haven't adapted well to the invention of the cellphone, let alone the smartphone. Being able to instantly communicate anywhere ruins so many plots.

I mean if you take the Marvel films, it's because interesting stuff is actually happening (to them) all the time. I wonder how many behind-the-scenes shots there are of the actors checking their phones in between shots, lol.

A more general remark would be that nobody in films ever uses the toilet.

They do if it's relevant to the plot. See - Pulp Fiction.

I guess it depends on on the movie, but wealthier cities have significantly less obesity rates then others, like cities in the US south east. There's not that many obese people where I live.

Yeah, I'm not just talking about obese people, cinema is almost completely devoid of even slightly overweight and out of shape people - ie. normal people.

SF is the best in California and it’s still just over 10%.

> It's weird that all movies seem to play in a parallel universe where everyone looks like the fittest people ever.

It's not weird if take consider commercial cinema for what it is - an escapist fantasy meant to induce short-term pleasure in the viewer. It's much more pleasant to look at attractive members of the opposite sex, than at the ordinary people.

> It's much more pleasant to look at attractive members of the opposite sex, than at the ordinary people.

Not only opposite sex! When I was a kid everyone watched action movies with fit guys like Schwarzenegger or Stallone shooting some ridiculous-looking machinegun or rocket launcher while being topless for no practical reason what-so-ever and everyone wanted to look like them! Granted, now I'm not into actions and don't watch modern superhero movies at all but I suspect people still like to associate with heroes of the movies they watch, so I wouldn't enjoy watching average fat American John McSmith acting as Rick Deckard that much...

I mean, who actually talks like the dialogue in a novel? Movies aren't supposed to be real life. You don't have to go to the cinema for that, it's all around you, in 3D, surround sound, even smell!

This is a pretty extreme article, but I think the argument is not that it doesn't exist but rather that it is blown out of proportion. The metric that is used to calculate obesity (specifically at the time they reference) was BMI which is a fairly flawed metric and significantly the obesity line was lowered. Idk how it is calculated now.

BMI is a pretty decent measure of fat percentage for the vast majority of people, it really only fails for people who have far more muscle mass than most people (body builders). It is highly correlated with health outcomes - people with a BMI over 30 (obese) have significantly higher risk of death from heart disease, stroke, diabetes, and cancer - this is true at a BMI of 30 and it only gets worse from there. 40% of americans are obese. It's not overblown - if anything, I think most people don't understand just how big of a health crisis it is.

> BMI is a pretty decent measure of fat percentage for the vast majority of people

It isn't really measuring anything. It is just a very general index to gauge how far you diverge from a predetermined height to weight ratio.

Maybe that's useful to someone but I wouldn't base any of my decisions on it today.

On the margins it may not be useful, but for the "average" person, it is definitely useful. I'd suggest there is no one with a BMI of 30 (besides people with a ton of muscle) that is at a healthy weight. Its a gut check, which is what is helpful.

You know what they say, most of the volume of a high-dimensional orange is in the skin. The average person is very rare.

BMI is best for populations since it's so easy to calculate from easily and frequently collected data. For an individual, you can fairly easily get more accurate measures to predict whatever it is you want to predict.

If you're not a bodybuilder and not pregnant, it's one of the simplest useful calculations we have. You'd be amazed at how many medical decision-making tools[0] are very simple and are based on outcomes, not rigorous mathematical theory.

[0] E.g. NEWS https://www.nice.org.uk/advice/mib205/chapter/The-technology

Claiming that BMI is flawed is a lazy half-argument. Finish the argument, what should be used instead of BMI? Look at the correlation plots and draw your own BMI line [0]. I think the BMI lines look pretty good for men, but for women who fall into the common BMI range of 25 to 30, the BMI formula tends to underestimate the amount of body fat.

It would be nice if everyone could get a DEXA scan regularly, but the data shows that 50% of people would find that they have even more body fat than the BMI charts predict. Again, it's worse for women, most women near the overweight threshold would find that their body fat is higher than expected.

[0]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2877506/

This needs to become more widely known. BMI underestimates obesity, not the other way around. Studies that use better measures of body fat percentage consistently find even people who are "normal" weight are fatter than they think. It's why doctors are supposed to now use waist to height ratio as a secondary predictor.

My issue with it is two fold.

I think due to its generalized nature there are exceptions where it doesn't even apply (like people who are weight training, pregnant women etc).

I also think it is becoming apparent that weight alone is not as useful of a metric as was once believed. It doesn't do a great job of identifying whether or not someone is healthy.

So maybe it is the best that institutions can do to gauge the health of a population with the data given, but I think it could be improved drastically with extra metrics (I've heard of measurements around the body being used).

There is a subset of people who are being misidentified as unhealthy or overweight. Idk how large it is but it seems significant.

Obviously there are edge cases when applying statistical tools at a population level. That's not the purpose of BMI though. If you're pregnant or weight training then OBVIOUSLY your BMI score is not comparable to others. Most people are neither pregnant nor weight training. I'd even bet that most people haven't performed a weighted squat.

>> I also think it is becoming apparent that weight alone is not as useful of a metric as was once believed.

Being fat is bad for your health. That is a fact. No amount of body positivity advertisements will change that fact. It is healthier to be thinner than obese. Look at the graph above to see BMIs impact on other health outcomes.

Also, if you think the obesity crisis is fake/blown up then simply go outside in most American cities and you'll see that many people are obese.

> There is a subset of people who are being misidentified as unhealthy or overweight. Idk how large it is but it seems significant.

Again, this is not relevant as the subset of people is so small compared with the whole population.

The "data given" is included in BMI. Your relative weight is an indicator of multiple other health outcomes.

> Reading your comments is tiring.

Then don't.

> if you think the obesity crisis is fake/blown up

I don't think obesity is fake or overblown. That's what the article was trying to argue.

I do however think BMI has its flaws and that those flaws are pretty significant when it comes to assessing individual health.

> Being fat is bad for your health... it is healthier to be thinner than obese

There is a healthy body fat % range but it is all very dependent on someone's activity and consumption.

> There is a healthy body fat % range but it is all very dependent on someone's activity and consumption.

The amount of body fat being detrimental doesn't change if you just exercise more or eat healthier. It's still bad by itself. You might have a better life expectancy than someone who is a sedentary lump at the same body fat, but that isn't saying much. Hence, again, BMI is a gut check. If you're at BMI=27, you almost certainly need to lose weight. Period.

> I do however think BMI has its flaws and that those flaws are pretty significant when it comes to assessing individual health.

While this is not untrue, I don't understand why people single out BMI as a measure to criticise. No measure is perfect, or even particularly good in many cases, and yet it's BMI that gets it.

It's easy. Its an excuse to not lose weight.

What do you mean by "weight alone"? Even BMI is kg/m^2 rather than just weight. Do you mean total body fat percentage isn't a metric of health, or BMI doesn't closely track BF%, or literally that weight isn't a good metric?

Sorry if this is nitpicky, but responding to the claim is difficult without defining it precisely. For example, see this figure from a study comparing BMI and BF% in Greece: https://www.researchgate.net/figure/BMI-versus-body-fat-perc.... You can see that BMI incorrectly says a lot of people are healthy when they're obese in terms of body fat, but if you don't agree that body fat is a metric of health then I'd first need to convince you of that.

Edit: I'll also note that in that figure you can see the number of people who are incorrectly labelled as obese by BMI but not by BF%, and it's much smaller than the other way round. BMI tends to make your population look healthier than it really is, whereas most people who say BMI is flawed are making the opposite argument.

> I think due to its generalized nature there are exceptions where it doesn't even apply (like people who are weight training, pregnant women etc).

All models are false, some are useful. BMI is imperfect, but arguing we should ignore it because it has exceptions is like arguing we should ignore that the Earth is round because it isn't perfectly spherical. Looking at BMI alone is occasionally misleading, but it's a hell of a lot better than not looking at anything, which is the realistic alternative.

> So maybe it is the best that institutions can do to gauge the health of a population with the data given, but I think it could be improved drastically with extra metrics (I've heard of measurements around the body being used).

No-one has identified any such drastic improvements. Measuring body fat percentage gives you a small improvement over BMI alone, but it's hard to do at home and only really matters for people with very high muscle mass (who are most likely already using more advanced measurements than BMI alone).

My eyes tell me that the obesity epidemic is real. Go to any public gathering of a couple dozen people or more and count the obese people you see. Heck, pick up a middle school yearbook, we’re starting obesity young these days.

We were hoping our future was Star Trek, but it’s looking more like Wall-E.

It's a starting point for sure, a more thorough research would look at body weight ratios.

That said, while BMI is a skewed metric for muscular people, statistically it's still more representative of obesity than 'dry' weight.

More like: there's a "missing middle" with respect to BMI which is common irl but underrepresented in media

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