美国大部分地区人均寿命下降

The obesity epidemic is not just an American health issue.  New data from the World Health Organization show that more than 1 billion adults around the world are overweight, nearly a third of them obese. Their weight problems are adding to the global burden of chronic illnesses such as diabetes and heart disease and swelling the number of premature deaths worldwide. Obesity is causing significant declines in longevity around the world, in poor countries and rich ones, including the United States.

A baby born in America in 2009 could expect to live an average of 78 years, according to estimates from the U.S. Centers for Disease Control (CDC). 

That's still true in many parts of the United States. But in some places, life expectancy has leveled off or even dropped slightly - a rarity in a developed country and, public health officials say, a cause for alarm.  A study in the Journal of Health Metrics shows the United States now ranks behind 10 other developed countries when it comes to life expectancy, even though Americans spend more on health care than people in most other countries.

The study had another surprising finding, according to journal editor, Dr. Chris Murray:

"It's a real surprise to us in the study that women are faring so much worse than men," noted Murray.

American women still live longer than men by five to eight years. But they have picked up some bad habits.

"Women are now smoking more.  The obesity epidemic in women is greater than in men. Progress in tackling blood pressure is much worse in women," Murray added.

Studies show the obesity epidemic is most widespread  in America's southern states. One study last year shows that in ten states in that region, two-thirds of the residents were either overweight or obese.

Dr. Morris Washington is a surgeon in South Carolina who is now performing bariatric or gastric by-pass surgery on morbidly obese teenagers.  He points to the southern diet, with its fried and rich foods that are high in calories.  He also attributes the obesity problem to too much sitting.

"We're basically a car society where we drive from one thing to another and basically do all your living right out of your car,” said Morris.

At the Harvard School of Public Health, Dr. Frank Hu has been studying sedentary lifestyles and their impact on obesity, type 2 diabetes and premature death.  He blames a lot of obesity-related diseases on time spent in front of the television.

“The more time people spend watching TV, the higher their risk of developing diabetes and cardiovascular disease, and also increased risk of death," noted Hu.

Longevity depends on many things, including getting exercise, good medical care and maintaining a healthy weight. But as Americans adopt more sedentary lifestyles and turn increasingly to processed, high-calorie fast foods, keeping off excess weight and living a longer, healthier life is a serious challenge.