Map of life expectancy at birth from Global Education Project.

Wednesday, January 02, 2013

Pleasingly Plump

Sorry for the long hiatus, I was distracted by a (very wonderful) personal matter. It turns out blogging isn't necessarily the most important thing in the world after all.

Anyway, despite the new year and all the ongoing political sturm und drang, I'm going to re-enter the blogosphere with a conventional Stayin' Alive post. Flegal and colleagues in the new JAMA present a very careful meta-analysis of studies linking body mass index with mortality. Their findings confirm what has been the general trend in observations over recent years: the categories of overweight and obesity set by NIH consensus panels may define healthy weight a little too stringently. People in the current "overweight" category (BMI between 25 and 29) actually seem to have slightly lower all-cause mortality than people of ostensibly "normal" weight, and people in the lowest category of "obesity" (BMI 30-34) do not appear to have higher mortality rates. Above that, however, obesity is most definitely associated with sharply higher risk of mortality.

But . . .

It's complicated. Underweight individuals have elevated mortality, probably mostly because the reason they are underweight is that they are already sick. Mildly overweight people may have good cardiovascular fitness and good muscle mass, or not: being both overweight and unfit is probably bad. Also, staying svelte in youth is probably a good omen for your later years. People tend to gain weight with age, but very few young people die, so when we're talking about mortality risk, we're talking about older folks who are naturally a little bit more zaftig than their younger selves.

Anyway, the point of all this is, if I were a real doctor, I'd tell you to pay more attention to being physically active and fit, and eating a well-balanced diet, than whether you're five pounds overweight by the standard measure. However, if you're much more overweight than that, you should try to trim down. And how can you do that?

Well, this one is abstract only for the rabble, but: the high fructose corn syrup and table sugar thing is probably real. It turns out that fructose -- of which there are similar amounts in both of the above-named products -- is the worst form of calories. Not only does it have a high glycemic index, it doesn't satisfy hunger, in fact it appears to make you hungrier. That's the crap in soda and supermarket sweets and the sugar bowl on your table. It's increasing prevalence in the American diet may have a lot to do with the obesity epidemic. Do not eat it! Have a piece of fruit.

Back to a normal schedule now, I hope.

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