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.
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.
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".
>rather than a medically-established ideal weight range
Is it really "abstract thinking" to accept an arbitrary "medically-established ideal weight range"? Shouldn't we evaluate the criterion set by the medical community too before we accept it? I hear constant criticism of the BMI system for determining healthy weights, yet I've never really known another standard system.
While I agree that it's bad to compare your chubby kid to the obese kids and write off the weight problem because fatter children exist, I'm not sure how far we should run with the insistence on conformity to numbers like BMIs.
If my children are in the "overweight" BMI range (which isn't applicable to them yet as both are under two) but I still feel that they've been exercising, eating well, etc., and are generally healthy, I'm not going to sweat it.
This is a key point. BMI by itself is not an accurate indication of a person's health. I often see discussions freely interchange being overweight with being unhealthly, even though we only have data for some types of health conditions correlating with higher body weight. To my knowledge, there is no single score or data point that can be used to accurately assess an individual's health.
>I often see discussions freely interchange being overweight with being unhealthly, even though we only have data for some types of health conditions correlating with higher body weight.
It's true, not all health conditions are correlated with being overweight. However, a good many of the deadliest health conditions, including heart disease, stroke, cancer, and diabetes are very well correlated with weight. Saying we should discount the effect of weight on health because my weight doesn't predict my susceptibility to car accidents strikes me as misguided.
>To my knowledge, there is no single score or data point that can be used to accurately assess an individual's health.
That's true, but it's also meaningless. There isn't a single score that allows you to predict everything. But, for most people, BMI correlates quite well with the "big-three" medical ailments: heart disease, stroke, cancer. I think that's valuable enough.
Slightly overweight 40+ year old people live longer than underweight or overweight people. Ideal weight vs Overweight is fairly even with some study's showing slightly overweight being heather.
> Saying we should discount the effect of weight on health because my weight doesn't predict my susceptibility to car accidents strikes me as misguided.
It's not my intention to make such a statement. BMI does have a usage, but it's more nuanced that most people realize and I wished to point that out.
> But, for most people, BMI correlates quite well with the "big-three" medical ailments: heart disease, stroke, cancer.
Do you have any more information or citations for this? It was my understanding that BMI alone was not enough of a predictor for certain ailments and conditions and that usually medical professionals also look at additional risk factors in conjunction with BMI, such as family history or habits like smoking.
More to the point, BMI by itself is not an accurate indication of a person's status with respect to weight.
BMI boils down to a ratio of weight to height. The fact that this definition doesn't include the word "fat" ought to be a clue that it won't be entirely successful as a measure of a person's fatness. In particular, because muscle tissue is significantly denser than fat. Thus, a couch potato and an athlete, each having the same height and girth, will score such that the couch potato will have a better BMI score than the athlete: BMI penalizes exercise to the extent that it generates muscle mass.
A much more informative measurement would be the body fat percentage. But even this falls down. Apparently there are two kinds of fat. Subcutaneous fat poses little health risk. Internal fat, surrounding the organs, is where the potential problems begin.
This is true, but overcomplicating things for most people. You'd have to be a serious bodybuilder to get to the "obese" range of the BMI chart and have that be healthy. The density of muscle is higher than fat but not so much higher (1.06 g/L vs. .9 g/L) to be able to get you to obese levels without looking like a pro wrestler.
The lower half of the "overweight" range is more ambiguous, but statistically speaking the health risks for this range are much less as well (and some studies have determined people in that range to be on average healthier than those in the normal range, perhaps because it includes more physically active people with more muscle). But if your BMI is at a level associated with severe physical health risks (30+ and especially 35+), it's unlikely that muscles are the explanation unless that's obvious.
To be "obese", maybe you need to be a serious bodybuilder, but being overweight is pretty easy.
My numbers: 6'5", 233lb, BMI 27.6 (solidly overweight), squat 180, bench 160, press 120, snatch 90. All numbers are 5 rep work sets except snatch, which is 3 rep work set. ORM might be higher.
The problem is that BMI was designed for sedentary people. It's a good guideline, but it's no substitute for a pinch test.
I am 6'2 and 235lbs, 16% body fat. According to The American Council on Exercise I am in the "fitness" category (Between athlete and average). However, according to the BMI, I am obese (BMI over 30). In order to have a BMI of less than 25 I would need to have a negative body fat percentage.
>Is it really "abstract thinking" to accept an arbitrary "medically-established ideal weight range"?
It is abstract thinking as opposed to concrete thinking, because you are imagining a hypothetical child with a certain build, (or is it a set of children with a range of healthy builds?) and comparing your child to that, as opposed to simply comparing your child to the other children you see in front of you every day when collecting your child from school.
Well, your link lists concepts like "Five" or "Justice" as abstract, so the entire concept of "overweightness" instead of just "overweight child" is "abstract" by that measure. I guess I assumed you meant something more meaningful and less pedantic.
And I don't think there's much of a leap in terms of abstraction if you just jump from "compared to the other kids, my kid is ok" to "compared to this number on a chart, my kid is ok". That is just a change in what data point you prefer to reference, not a change in thought patterns.
I think the parents are right to interpret the terms that way. They are not misinterpreting the weight of their children, they are just answering survey questions based on their own points of view and relative observations.
This seems to happen a lot. I've seen many surveys where group x is seen as "uninformed" when in reality, it's because the group has a differing opinion than the person giving the survey.
I guess it depends on how the studies were conducted (I haven't looked). They may well take steps to eradicate this problem.
However, I suspect you are right and - in actual fact - this may really be what the studies are concluding: that parents of overweight children do not see the problem because the average they see around them is not medically-healthy normal. It would be interesting to see the average weights of children in the study areas to see how much the theory stands.
It would also be interesting to see a similar survey that asked whether they thought their child was within the healthy bounds (i.e. no classifications like "overweight" where they could draw comparisons).
There's an interesting study in the New England journal of medicine related to this. The authors found that having social ties to an obese person significantly increased an individuals chance of becoming obese.
From the study:
A person's chances of becoming obese increased by 57% (95% confidence interval [CI], 6 to 123) if he or she had a friend who became obese in a given interval.[0]
One of the authors is quoted as saying:
“You change your idea of what is an acceptable body type by looking at the people around you,” Dr. Christakis said.[1]
I can see you point but the kids mentioned in the survey are from the most obese 15% of the population so they really are chubbier then their neighbors.
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."
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.
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.
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.
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.
As an overweight parent, I know I'm overweight and am working to change that, with slow, but steady results.
I've always been very conscious of my child's weight, because I don't want her dealing with the same feelings of shame, discomfort, lack of energy, etc. that I went through as a kid, or to face the medical problems later in life that I'm now working hard to avoid. This is, for me, a Really Big Deal. Being overweight sucks. I want better for my kid.
If anything, having a kid has helped me, because teaching healthy lifestyle and eating habits by example is far better than telling her one thing and doing something totally different, myself.
On the other hand, I have an overweight friend with a 100+lb, average height, 9yr olds who will argue all day that the kid "isn't fat."
That is certainly what my money would be on. Below a certain age, kids don't tend to become fat unless their parents let them (that whole being provided for thing sees to that).
I wonder how much of this effect is just due to the fact that admitting the child is overweight would be tantamount to admitting that they themselves are overweight. Without making any moral statement whatsoever, that's simply hard for people to do.
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:
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?
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:
To this poster's benefit, I also vaguely remember an article about this, but it was for a specific disease (possibly heart related?). It was only a tiny benefit for the people who are in the first group of overweightness.
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.
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?
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.
Assuming that the claim is true that people with a BMI of 25-30 live longer than any other BMI range, how is believing that claim denial? Or in other words, what do you think that poster is denying?
So even sizes in stores work to make people feel they're ok. 1X isn't "extra large" It's "woman sized". WTF?
There are communities where that's considered a good thing. I recall an episode of 3rd Rock from the Sun where one character was looking for a dress, and was dismayed to find that the standard sizes were designed to make women fill overweight and inadequate (it turned out that the store had been taken over by impossibly-thin supermodel aliens, IIRC).
If the trade-off is between being happy and size X, but dying early, or unhappy and size X, and dying early, which is better? How do you convince people to be happy about where they are by being happy about where they're going?
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.
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.
The methedology of the original 2005 study has been questioned. To me it sounds like the researches may have conflated weight loss caused by illness with having a low BMI at time of death.
"... epidemiologists from the ACS (American Cancer Society), American Heart Association, Harvard School of Public Health, and other organizations raised specific methodologic questions about the recent Centers for Disease Control and Prevention (CDC) study and presented analyses of other data sets. The main concern ... is that it did not adequately account for weight loss from serious illnesses such as cancer and heart disease ... [and] failed to account adequately for the effect of smoking on weight ... As a result, the Flegal study underestimated the risks from obesity and overestimated the risks of leanness."
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?
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).
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.'
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.
- 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.
