In the midst of a pessimistic article about future trends in life span (that fails, like most, to consider the effects of current technological development on historical and short term trends) we find this item for consideration:
Obesity, [Olshansky] said, is "a global pandemic" that's already reduced life expectancy worldwide by 3.5 years. The effect of obesity on longevity is about the same as cancer, he said, and will double or triple in coming years, shortening lives by seven to 12 years.
Now I certainly don't agree with most of Jay Olshansky's propositions. His views on the possibility of increases in life span through directed medical research into the aging process are very unreasonable and he has not yet defended them in a rigorous fashion.
EDIT: Just to be clear here, I'm not disagreeing with Olshansky's conclusions regarding obesity and its effects on life expectancy, or calling into question this piece of research. What I do take issue with are his representations in the media regarding the dim prospects for healthy life extension through medical research. I - and to a lesser extent the scientists below - are skeptical about a decrease in overall life expectency because we expect to see gains due to advances in medicine.
Even other scientists who are not looking towards a future of radically increased healthy life spans are criticizing the projections made in this article:
"The modern era of dramatic increases in life expectancy is about to come to an end in the developed world - including the United States - as well as in the underdeveloped world," said Jay Olshansky, a demographer at the University of Illinois in Chicago.
"Life expectancy might very well decline in this century," he told last month's annual meeting of the Institute of Medicine, a branch of the National Academy of Sciences in Washington.
"Biology can play out quite differently in different countries at different times," said Richard Suzman, associate director of the Institute of Aging at the National Institutes of Health.
"Jay Olshansky's position is a minority perspective in demography," Suzman added. "However, majority positions in science sometimes turn out to be wrong, and so minority positions should certainly be entertained."
"There is a small chance - less than one in 100 - that Olshansky's prediction of declining life expectancy might possibly prove correct," Vaupel said.
Another skeptic is James Oeppen, a researcher at the Cambridge Group for the History of Population and Social Structure in Cambridge, England.
"If Dr. Olshansky is correct, he won't have to share the accolades with a large group of like-minded contemporaries," Oeppen scoffed.
Still, one cannot argue that excess weight in the form of body fat has been shown to be very harmful to your long term health. It greatly raises the risk of suffering all of the most common age-related conditions, shortens your healthy life span and increases your medical costs. I think that pointing out the comparison to cancer in terms of effect on life expectency is a powerful motivating argument. It's certainly something to think about if you are one of those people who needs that extra something in order to work towards better diet and lifestyle choices.