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internetcivilian t1_je0o0p2 wrote

Reply to comment by karanbhatt100 in Adult Obesity Prevalence Nearly Matches Heart Disease Deaths [OC] by orgborger

Oh the irritating crowd you're referring to can and will change the science (as they see it) like so:

  1. Undermine BMI as a metric using the lack of association between the "overweight but not obese" category with negative health outcomes.
  2. Argue that this invalidates the metrics for "obese" as well.
  3. Argue that no metric has perfect 1.0 correlation of obesity and negative health outcomes.
  4. Conclude that obesity is a social construct that is completely unrelated to health.

All while claiming they "follow the science"...

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Marksd9 t1_je0xgfl wrote

I wouldn’t consider myself smart enough to make a serious argument on this one way or the other but would you mind explaining why your first point isn’t worth taking very seriously?

Every reputable source I’ve read agrees that BMI is a flawed system of measurement. If that really is the case then don’t points 2,3 & 4 naturally follow?

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zombienudist t1_je1a7t1 wrote

It isn't flawed for most people. What most people see as a flaw is that BMI doesn't work for aberrations. So you are a body builder that BMI says is obese when you are 10% body fat. But very few people are bodybuilders.
That is why there is a range of weight for each section. And there are many other ways to measure your health. You can take measurements for example. Or use hip to waist ratio But take it from a guy that said that BMI was BS for much of their adult life that I was wrong. For most people it is a good guideline. I said that because I didn't want to face the fact that I was overweight from the time I was 25 on.

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Marksd9 t1_je1pqmd wrote

That makes some sense to me, some outlying body types can throw the data (although I’m given pause given that some of those outliers include entire ethnicities).

But even given more accurate testing we can all observe that some larger people are more active and eat more healthily than many skinnier people.

Given that conclusion, just how useful is body size as a measure of health?

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zombienudist t1_je1ua9m wrote

Again there are always outliers. That is why you don't just use one method. But it is clear to me looking back that I was lying to myself about my health and weight. Many, many people are. I know the things I said about BMI and I did that because I didn't want to face my own issues. It was easier to think that BMI was BS then to actually look at it seriously and use it as just one way to assess your health. If you are the outlier then you just use something else.

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internetcivilian t1_je11yuw wrote

Oh I'd be happy to explain! The thing here is that 1 and 3 are true statements stitched together in a misleading way.

The assumption that I'm making but not proving is that poor diet and sedentary lifestyle contribute to negative health outcomes. Furthermore, excess body fat is strongly associated to said poor diet and sedentary lifestyle (lots of calories, few nutrients in proportion to those calories, no burning off of said calories through exercise). I see this as invalidating 4, but of course I would need to provide papers showing the correlation and I'm going to be lazy and just state that these papers exist. Wikipedia has some OK links to said papers.

Notice that excess weight as an indicator immediately weakens the correlation since not every overweight person will experience negative health consequences as a result and we also need to figure out how to measure "overweight". So, there's some built in "fuzziness" right away (as noted by 3) but this is accepted because there's advantage in people being able to test at home with limited equipment AND excess weight is bad for a few other reasons (hard on joints, difficulty with accessibility, etc.).

With that in mind, reading wikipedia, and checking the linked sources leads me to believe that 1 is true. However, this observation does not undermine all metrics nor the practice, only BMI (this is my rebuttal to 2). It's just an invitation to try a bit harder. Waist to hip and waist to height ratio seem to do a better job than BMI, and body fat percentage (measured on a smart device or whatever) does an even better job.

These are my thoughts. I am not a medical professional and so constructive criticism is welcome!

Tl;dr 1-4 is basically a "bad apple spoils the bunch" style argument.

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Marksd9 t1_je1mxpd wrote

Thanks for the detailed response. I find the area really interesting since I grew up in an environment where BMI and the dangers of being “overweight” were totally unchallenged.

However the “fuzziness” around this topic always bothered me. Playing rugby, almost every player on my team would be classed as either “Obese” or “morbidly obese” (especially if they were POC’s) despite being high-level athletes. Meanwhile my skinny stoner friends who sat around playing guitar hero all day were classed as being “healthy”, based on a metric that even it’s proponents agree makes no sense. I would say everyone has similar stories of larger people being healthier than many skinny people.

The fussiness extends to the outcomes too, since obesity is only a co-morbidity and also doesn’t apply in all cases it’s easy to say a “fat”person’s weight contributed to a heart attack when that either may not have been the case at all, or may have been a contributing factor but not the actual cause. It may be just as accurate in these situations to suggest that the added stress of being left handed contributed to a heart attack.

This very much sounds like I’m making a very specific argument but what you’re really hearing is my brain melting as it tries to decide between two conclusions:

  1. Obesity IS the major health risk I’ve been led to believe despite the “fuzziness” in the data and observable conclusions.
  2. Activists are correct when they say that all the data starts from the point that “fat is bad” and works backwards to justify that conclusion.

TL:DR I’m too dumb and my brain hurts.

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