Comments on OBESITY PANACEA: Self-assessment of obesity in children is influenc...

@ RJ I agree with you 100%. Peter and I are big ...

2009-07-23T07:44:13.222-04:00

@ RJ

I agree with you 100%. Peter and I are big proponents of using WC as opposed to, or in conjunction with BMI. In this post, I was referring to BMI as "objective" as opposed to "subjective" measures such as self-report questionnaires. Your point is well taken.

Travis

We hear a lot about BMIs - and in your article you...

2009-07-23T06:40:38.134-04:00

We hear a lot about BMIs - and in your article you referred to the body mass index (BMI) as an " objective measure of obesity"

The BMI isn't actually a measure of obesity on an individual level.

World class athletes who are very muscular will be obese by this measure (when they in fact have very low body fat, and are super-fit)

It also varies depending on race/ethnicity - for example Pacific Islanders/Maori tend to have heavier bones, more muscle per pound, and the obesity threshold moves, depending on the race of the person.

My understanding is that BMIs were developed to measure the levels averaged across a population - changes in a populations average BMI would be useful information.

I am concerned that too often, in diet/health/beauty magazines in particular BMI is used to stigmatise healthy people of a certain heritage (when sometimes people with an acceptable BMI can be quite unhealthy).

As I understand it, the better measure is waist circumference.

I like your blog, and appreciate the analysis and approach - please take this comment as a comment not a complaint - and a reminder that we need to be careful how we use the BMI measurement.

@ Kate, You make a good point and yes, that is th...

2009-07-02T17:43:37.812-04:00

@ Kate,

You make a good point and yes, that is the exact wording they used. It would be ideal if the authors had just said "Do you think you weigh the right amount, too much, or too little?". As it is, it's possible that it did pre-condition the students a bit. From the methods, it sounds like this was a post-hoc analysis, which may explain why the wording wasn't ideal.

But that being said, the meat of the question was still "do you weight the right amount, too much, or too little", not "do you weigh more, less, or the same as most of your classmates". If a child were to recognize that they and their classmates were overweight, I don't think they would answer that they weigh "the right amount". If they recognized that they were all overweight, they would still probably pick "too much".

I'll concede that the scenario you describe is plausible, but I don't think it's likely to completely explain their results.

Is that the actual question students were asked? ...

2009-07-02T14:10:38.046-04:00

Is that the actual question students were asked?

Maybe I'm too literal, but that question to me seems to be asking students not to estimate their body weight relative to "normal" but instead to estimate it relative to the average body weight of their classmates.

I.e., it seems to me that the question is asking students "do you think you weigh more than, the same as, or less than your classmates", not "do you think your body weight is normal" or "what is your BMI"--which is what this post seems to imply is being asked.

It's the phrasing of the question that's problematic. If you ask students to compare themselves to their classmates, they're going to tell you whether they think they're bigger, smaller, or the same size. But that doesn't necessarily tell you whether they recognize that the average weight of their classmates is too high, too low, or "just right".

If this is the actual question that's asked, then it's possible for an overweight student surrounded by overweight students to both a) recognize that s/he (and other students) is overweight AND b) answer "just right".

@ Rihcard, That is certainly one of the implicati...

2009-06-29T14:28:50.028-04:00

@ Rihcard,

That is certainly one of the implications that I would take from it. Although on the more positive side of things, it might mean that we only need to get a certain critical mass of people in a social network to adopt healthier behaviors, and that the rest will follow suit.

Extrapolating out, could that mean that a society ...

2009-06-29T14:22:31.163-04:00

Extrapolating out, could that mean that a society has a tipping point after which there is an increase in the change of weight of the population in general because the bigger size becomes the norm?

ie the population in general gets bigger more quickly, after the tipping point.