An Oxford University study, published in The Lancet, collected data from 57 other studies done on nearly 900,000 people, starting in the mid-1970s, and found mortality was lowest when the Body Mass Index (BMI) was between 22.5-25.
The headline here is that the risks of weight are similar to those of smoking. If your BMI is 30 your lifesspan is cut by roughly 2-4 years, the study says. Get up to 40 and your life is cut short by up to a decade.
You calculate your BMI by dividing your weight by your height, as at this site. At my current weight of 220 and height of 6'2" my BMI is 28.2. I would need to lose 25 pounds to reach a BMI of 25.
This should tell you just how bad things are because most of my friends think I'm trim. But my excess weight is the equivalent of smoking a half-a-pack of cigarettes each day. A BMI of 30 is now pretty common.
Sir Richard Peto, who conducted the Oxford study, told The Guardian smoking is still worse for you than Big Macs. "Smoking matters enormously more" than obesity in shortening your life, he told the newspaper. So if you gain some pounds after quitting you're still ahead.
But wait, there's more. A study in Texas finds that fat people experience worse outcomes after surgery for pancreatic cancer. Those with a BMI of 35 are also more likely to get the cancer. A Canadian study says the overweight are more likely to miss work, be unproductive, or suffer job stress.
One result is articles like this from physicians assistant Elizabeth McPhilomy, suggested plans for weight loss that work like anti-smoking interventions, with appointments made just to counsel people on weight. This would put doctors in direct competition with weight loss clinics.
There is also a backlash.
Sociologist Samantha Kwan at the University of Houston (go Cougars) wants to de-emphasize the BMI, calling obesity a social problem that doctors have tried to "medicalize."
Lewis Page of The Register riffs off Kwan's research calling obesity a "moral panic," but noting that those who die young at least leave stuff for the rest of us.
Personally I think absolute faith in the BMI may be overdone. My gym coach is a heavily-muscled guy who seems not to have an ounce of fat on him but I'm sure his BMI is higher than mine.
Although, yeah, I could stand to lose a few pounds.