Now they're saying that average BMIs lead to early death
There are two fat and health items in the news right now.
The first - the request from lap band manufacturers to the FDA to lower the BMI where lapbands are allowed - was covered by AndyJo in the previous post.
Another study, published by New England Journal of Medicine with Amy Berrington de Gonzalez as the first author, is being reported on in articles such as ABC New's "Higher Body Mass Index Linked to Greater Mortality Risk" and touted as "proof" that people in the 25-30 BMI ("overweight") and the 30-35 BMI (obesity type one) categories are at increased risk of death because of their weight. This study is a data dredge, that is, it's built on data from older studies that could have been cherry-picked to get the desired results. It's obviously meant to refute Katherine Flegal's 2005 study and a recent Canadian government study, both based on population-level mortality statistics and both of which indicate that people in the the 25-35 BMI range have an average or above average life expectancy.
The flaws in the new de Gonzalez study? Well, I haven't read it myself, but I'm hearing from medical professionals who have read it that it doesn't control for level of physical activity - or health insurance status (!!). It's interesting that it was published shortly before this request to expand the market for lapbands. Lucky for the lap band manufacturers, eh?
There's a great post on both studies on Suethsayings: Push for weight loss surgery even if you have a lower BMI follows study about obesity.
Health and science reporters? If any of you are reading this, please look at the quality of the research before suggesting that a data dredge invalidates large, comprehensive and well designed studies like "BMI and mortality: results from a national longitudinal study of Canadian adults" (Orpana et al, 2009) and "Excess Deaths Associated With Underweight, Overweight, and Obesity." (Flegal et al, 2005)