The increased girth isn't just a problem in the United States, where two-thirds of adults are overweight. As Rose Hoban reports, it's a problem that's becoming globalized.

Obese people can develop medical problems including diabetes

Psychiatry professor Rena Wing from Brown University in Providence, Rhode Island, says researchers are startled to see rising rates of obesity in countries that recently had trouble feeding all of their citizens.

She says China is a good example. "China has adopted Western ways. [They have] more emphasis on the automobile, more emphasis on fast food, and unfortunately with that, has come a rise in rates of overweight, and unfortunately even some obesity."

At the recent meeting of the American Association for the Advancement of Science in Boston, Wing and Professor James Hill from the University of Colorado debated what to do to combat obesity worldwide.

Hill says if people make small changes, it's enough to reduce weight. He's a proponent of cutting food intake by 100 calories per day, or walking one and a half kilometers a day, or both.

But Wing argued that's not enough. She says the data suggest larger changes are needed. "For example, we're going to need to do 60 to 90 minutes of physical activity a day to prevent weight gain and to prevent weight regain in individuals who've already lost weight," Wing says.

Wing has good data to back her up. She and Hill started the National Weight Control Registry several years ago to study what keeps people from regaining weight that they lose.

The 5000 people in the registry who were successful at losing and keeping weight off made large changes in their dietary intake and physical activity. And, Wing says, when they stopped practicing their new, good habits, the weight came back.

"We find … that members of the registry report eating about 1400 calories a day," she says. "We know that people underestimate their intake by about 30 percent, so our best guess is that they are eating about 1800 calories a day, which would still be a very restricted dietary intake."

Wing says people who are successful at losing weight and keeping it off report eating about 26 percent of their calories from fat. They go to fast food restaurants very rarely (less than once a week), and they report eating breakfast pretty much every day of the week. They also are very consistent in reporting a very high level of physical activity.

Wing says successful weight losers also report they watch little TV, weigh themselves regularly, and are vigilant about keeping track of the amount of calories they eat.

She says these are habits we need to instill in people to begin to overcome this newly globalized epidemic — what she calls glo-besity.