
Parents of overweight children don't know their children are overweight - yummyfajitas
http://theincidentaleconomist.com/wordpress/how-deep-can-we-get-our-heads-underground-ctd/
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patio11
Quick guess: "How can little Timmy be overweight if half the kids in the
neighborhood are chubbier than him?" (Psst: not that difficult, actually.)

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JonnieCache
Indeed. I would say that because of various inherent cognitive biases, people
are likely to interpret terms such as "overweight" as a comparison to their
local average, rather than a medically-established ideal weight range.

Such abstract thinking just doesn't come naturally. We are incredibly biased
here because our jobs often require little else _except_ abstract thinking.
This is massively atypical.

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ErrantX
I think you have hit the nail on the head. This brings to mind one rather long
and tedious "discussion" I had on Wikipedia last year that revolved around
whether "above average" was an adequate way to summarise "Overweight and
Obese".

Getting across the concept that the latter terms were - in the context of the
source - medical definitions and not going to change with the (ill-defined)
average, was difficult at best. There was a lot of "but _obviously_ being
overweight means you are above average".

I'm not surprised to see others observing the same issue in different
contexts.

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rapala
By my observation, this is pretty common logical fallacy. If from A follows B,
many will deduce that from B follows A. This often happens in math, when a
lemma says that A => B is true. Many will use the lemma "the wrong way
around".

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billybob
A lovely interchange my wife overheard in a medical office:

Parent: "He needs to gain weight, right?" Doctor: "Why do you think that?"
Parent: "You can see some of his bones!" Doctor: "You're SUPPOSED to be able
to see SOME of them."

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rmassie
I see so frequently that when a child is overweight, their parents are
overweight as well. I wonder what their perception of their own weight is.

~~~
firefoxman1
It's really crazy how your eating habits are influenced by your parents. My
mother is really into eating really healthy and both I and my sister eat
healthier by choice now. I remember when I was really young my mom's friends
were impressed that I willingly ate vegetables...they were actually impressed
by that! I would always notice the look on my mom's face like "...uh why
wouldn't he?" It's really kind of sad that eating your vegetables nowadays is
_impressive_.

~~~
JonnieCache
Peoples' perception of various tastes vary dramatically, partially through
genetic factors (some people are even termed "supertasters,") but also with
age. There is research showing that children perceive bitterness especially
strongly, and that this attenuates with age.

See: <http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3087510/> _Age modifies the
genotype-phenotype relationship for the bitter receptor TAS2R38_

So when some children say they don't like vegetables, it may not be such an
illegitimate claim after all. I personally still cannot stand brussel sprouts,
into my mid 20s.

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dgordon
I never had them until my mid-20s, but apparently a lot of people's only
experience of brussels sprouts is boiled to death, which allegedly increases
their bitterness. I've had them roasted, and they were reasonably good.

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SNK
Since so-called overweight - BMI 25-30 - is the longest-lived cohort, I'd say
parents aren't the only ones with distorted perceptions.

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drblue
Citations please. If that was true, I've learned a new fact that conflicts
with most of what I know about obesity having an effect on, for example, heart
disease.

The first link when googling for "lifespan by bmi" is:

[http://wehrintheworld.blogspot.com/2009/05/bmi-and-life-
expe...](http://wehrintheworld.blogspot.com/2009/05/bmi-and-life-expectancy-
results.html)

Which cites two metareviews. The first is a collaboration between the UK
Medical Research Council, several British organizations including one out of
Oxford, and the US National Institute on Aging (which is under the NIH
umbrella). It was published in _The Lancet_ (Impact factor: 33). I will quote
the quoted part from said blogpost:

> BMI is in itself a strong predictor of overall mortality both above and
> below the apparent optimum of about 22·5–25 kg/m2. The progressive excess
> mortality above this range is due mainly to vascular disease and is probably
> largely causal. At 30–35 kg/m2, median survival is reduced by 2–4 years; at
> 40–45 kg/m2, it is reduced by 8–10 years (which is comparable with the
> effects of smoking). The definite excess mortality below 22·5 kg/m2 is due
> mainly to smoking-related diseases, and is not fully explained.

While I found a few studies that didn't find a correlation (including one in
AMA), I can't actually find an academic source for the claim that people with
a BMI of 25-30 have the longest lifespan and see _lots_ of claims that the
optimal BMI is in the low 20s. Do you have any citations handy?

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blahedo
If you run a search for '"slightly overweight" live longer', you'll turn up
links to a number of different studies in a number of different jurisdictions
that have shown this. For instance:

[http://lifehacker.com/5303009/being-slightly-overweight-
coul...](http://lifehacker.com/5303009/being-slightly-overweight-could-lead-
to-longer-life)

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niels_olson
Here's my experience in primary care: obese parents bring in their obese child
with a complaint of some minor illness. My sense is they tend to be less
confident in themselves than leaner folk, so they tend to resort more
frequently to more physical positioning to get an antibiotic for their kid's
viral URI. It probably doesn't help that they had to endure more stress at
home before rising to the necessary motivation to move, then moving itself is
more of an effort. By the time they've been sitting in the waiting room for an
hour and the clinic room for 10-15 minutes, they're just in a foul mood.

Being in a closed room with large, physically unhappy people can be
intimidating, never mind that there's a waiting room full of other patients.
Rather than addressing ancillary issues head on, it's infinitely more
convenient to focus on customer service for their immediate issue.

The issue needs to be addressed in a more benign setting.

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robododo
I found it really interesting that someone piped up in the blog comments
disagreeing with the measure for overweight: "Since so-called overweight – BMI
25-30 – is the longest-lived cohort, parents aren’t the only ones with screwed
up perceptions, IMO."

Denial's everywhere, I guess.

Tangentially related: I was buying a coat as a gift for my mother, and was
perplexed by the sizes. So I went to my local expert: Me: "What's up with all
the women's sizes? They're all 1-X, 2-X, etc." Wife: "Oh, 'woman' sizes mean
fat. Misses means normal." Me: DOES NOT COMPUTE

So even sizes in stores work to make people feel they're ok. 1X isn't "extra
large" It's "woman sized". WTF?

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Dylan16807
Bringing up conflicting evidence in a scientific discussion is denial?

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mikeash
Bringing up a single piece of conflicting evidence and using it to declare the
other side to be completely wrong is _definitely_ denial.

~~~
Dylan16807
I don't read that as declaring the other side completely wrong. That study was
for people a _little bit_ overweight, while the apparent delusion of parents
extends into the very overweight. Even the phrasing of "aren't the only ones
with distorted perceptions" suggests that _both_ sides have their failures.

~~~
mikeash
This may just be a pessimal interpretation of humanity, but I definitely read
that sort of flip response as a quick way to dismiss the entire side's merits,
attempting to show that they have an obvious agenda, are ignoring something
obvious that shows they're wrong, etc. I certainly could be misinterpreting.

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redfiche
I don't understand this, it's such a routine part of the doctor visit for my
two sons for them to tell us what percentile the boys are in for both height
and weight. At one point one boy went above the 75% in weight and we
immediately made changes. Are pediatricians really not giving out this data on
a routine basis?

~~~
Someone
As another reply said, being heavier than the average kid need not be a
problem, e.g. When your kid also is taller than normal.

Your logic is broken (or you do not present all of it) in a different way: a
quick google gives me the impression that for kids in the USA, the 75th
percentile is about the edge case, but you need extra data to convert
percentiles to 'being too heavy'. In the extreme, if everybody is overweight,
even the lightest percent of kids will be overweight).

~~~
redfiche
My only intent was to say that in my experience some data has been quite
readily available. In our case it was enough data to understand our son's
weight was trending in an unhealthy direction. We made small changes to the
quantity and quality of food available to him and reversed the trend. The 75th
percentile just happened to be the trigger in our personal case. I make no
suggestion that it is an appropriate trigger in general, or that it equates to
'being too heavy.'

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tokenadult
"Does Weight Matter?" by Steven Novella of Science-Based Medicine

[http://www.sciencebasedmedicine.org/index.php/does-weight-
ma...](http://www.sciencebasedmedicine.org/index.php/does-weight-matter/)

has a good discussion of the definitional issues. The article links to pro and
con sources about whether excessive weight can lead to health problems, with
discussion of logical fallacies related to arguments on the issue.

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blahedo
Oh, where to start.

\- BMI is a poor measure of obesity. Among other things, bone and muscle are
both significantly denser than fat. People, including children, with thicker
bones and/or more muscle will have higher BMI regardless of fatness. So it's
at best a poor proxy for fatness, not the One True Measurement that so many
people use it for.

\- BMI is an especially poor measure for children. The ideal BMI (to the
extent that means anything) varies according to developmental stage. Which is
why you'll get tables and graphs for BMI that are indexed by age---except that
age and developmental stage are themselves only roughly correlated, and a
child at an earlier or later stage than is typical for their age will _not_ be
well-described by such a chart, and the "ideal BMI" that the chart lists for
that child's age will actually be a non-ideal BMI for that child.

\- BMI _percentile_ is an even _poorer_ measure, because it provides only a
comparison against the population; if the population is skinny, even a high
percentile might not be overweight, and if the population is fat, even a low
percentile might be overweight. And that's modulo all the concerns in the
previous two paragraphs.

\- Even after taking _all_ of that into account, we _still_ have the problem
that our conventional idea of "overweight" meaning "more weight/fat than is
healthy" is likely inaccurate, in that some amount of certain kinds of fat
actually make one healthier, and (as cited elsewhere in this thread) people
who fall into the range often called "slightly overweight" actually live
longer.

So evaluating kids' health (or their parents' assessment thereof) with
reference to their BMI percentage is fraught in _four different ways_ with
inherent, systemic problems.

