BMI of 25-29.9 showed the lowest rate of All Cause Mortality

[Mark Rippetoe]

Smoking is always controlled for.

[Will Morris]

Does the actual article show mortality rates for bmi's for specific age groups?

The article has it broken down by BMI 25-29.9, BMI greater than or equal to 30, BMI 30-34.9, and BMI >35 further broken down by all age categories, Mixed Ages (ages 25-64, ages 40-80), and ages greater than or equal to 65. Also, it reports hazard ratios of mortality.

Since it has been brought up already in the academic sector, one of the weaknesses of this study is that there is no study of morbidity, nor is there any determination of specific mortality rates at certain BMIs. But, that wasn't the point of the study. The study was an overarching study designed to see what the mortality risk was for overweight, obese, and morbidly obese as compared to "normal" BMI. It would appear that this study supports the weakness of the BMI at predicting health, and in fact, a person in the overweight category seems to be healthier than someone at a "normal" BMI.

[Will Morris]

Someone else already pirated the article. Here is the full article: http://extremelongevity.net/wp-content/uploads/fat.pdf

[ColoWayno]

Also, let's not forget... BMI might not be a good predictor of individual risk (or benefit) at all. If anything maybe this study can move us away from relying on BMI which is a very simplistic measurement. I don't think we should be telling people to each cheeseburgers just to get into the new "healthy" zone, just like we should have never been telling people to lose weight (regardless of body fat %, level of conditioning/strength, etc.) to reach a certain BMI.

Disclaimer: I like and eat cheeseburgers regularly and my BMI is 27.5% which makes me pefect as well as immortal.

[CFPeterson]

Doesn't the BMI crowd assume basically that all weight over some "ideal" weight is fat? I mean, it would be nice to have an easy way of taking simple measurements and making health judgments from them, but it just doesn't seem that easy.

[beastmaster103]

Filed and slated for review. THanks, William.

Sully:

I have a sister and brother-in-law that are DO's. Both of them seemingly swear by the BMI. I've tried to explain to them the shortcomings of the BMI, but they don't want to listen. Do you have a quick link to the pay site where someone would be able to view the document in its entirety? I'd love to forward that to them.

Thanks - Ryan

[Memdoch]

Smoking is always controlled for.

"Articles that reported HRs for all-cause mortality using standard body mass index (BMI) categories from prospective studies of general populations of adults were selected by consensus among multiple reviewers. Studies were excluded that used nonstandard categories or that were limited to adolescents or to those with specific medical conditions or to those undergoing specific procedures."

This guy says the J curve is the result of smoking and when controlled for smoking the "benefits" go away. The overwhelming majority of people with slightly overweight BMI are not that way because they enjoy squats and milk. He says that it's not a health risk if you're 'overweight' due to muscle mass, so we can be happy about that, but that is not what the original link was saying.

http://youtu.be/Qk4UKD00aOo?t=9m25s

(Relevant sections starts a little before ten minutes)

[LudwigVan]

And this comports pretty well with what we already know -- "we" meaning us cool people on this board.

How, exactly? Do we think that the average person with an overweight or grade-1 obese BMI got that way because of their unusual amount of muscle mass? That doesn't seem likely to me, so I'm not sure how much lifters should be laying claim to this result.

Moreover, in the studies I've seen which compared BMI-defined obesity to bodyfat-defined obesity (eg [1], [2]), BMI is found to have a high specificity (>90%) but a very poor sensitivity (~50%). So >90% of people with obese BMIs are in fact obese by body fat percentage, but up to half of people with normal BMIs may have obese body fat percentages as well.

[wes]

Wish I could edit, but to clarify.

Removing studies focusing on specific conditions prevents those conditions from being overrepresented in the study population. But if these conditions are more prevalent in some BMI ranges then others, then the aforementioned removal of studies does nothing to control for this (nor does it intent to). In fact, detecting such things would be part of the purpose of the study. Unfortunately unlike obesity contributing to a heart attack, the relationship is reversed with conditions like cancer contributing to weight loss (opposed to vice versa).

I definitely get your point. I guess mine is that people who are emaciated from cancer may be excluded from general population studies, which it seems is what the authors were drawing their data from. I can't back that up though.

Now I'm interested, I might go to the library and actually read the study.

[Mark Rippetoe]

How, exactly? Do we think that the average person with an overweight or grade-1 obese BMI got that way because of their unusual amount of muscle mass? That doesn't seem likely to me, so I'm not sure how much lifters should be laying claim to this result.

I think it's obvious that I mean lifters. And you need to gain some weight and quit being so proud of your abs.