COLUMBIA, S.C. - Eat smart, move more - it seems like a sensible thing to do.

Many people acknowledge that, but do just the opposite. The result? High levels of obesity among both adults and children. The medical costs associated with obesity are estimated at $90 billion a year.

No wonder policy makers and researchers have been thinking of the epidemic and its solutions in terms of financial gains and losses.

Health economist Eric Finkelstein noted that in the United States, although societal norms are more accepting of thin bodies, the economy drives behavior that makes people fat.

Cheap high-calorie fast food is prevalent even in rural areas.

"Food prices have never been cheaper, and access has never been easier," Finkelstein said. "Once the cost of an activity goes down, it's easier to do that behavior."

But whereas it's cheaper and easier to eat extra calories, it's become harder to burn them off as television and other pastimes compete with physical activity.

"It's not that we don't have time, we're just not choosing to use that time for physical activity," Finkelstein said.

Technology has made our jobs better, faster and easier.

"The economy is driving us to engineer physical activity out of the workplace," said Finkelstein, author of "The Fattening of America: How the Economy Makes Us Fat, If It Matters, and What to Do About It" (Wiley, $26.95)

Plus now there are medicines that help people stay healthy even when overweight.

Although economic forces drive behavior, health concerns should take precedence over economic ones when addressing obesity, Finkelstein said.

The private sector can get in on the act by using incentives or other strategies to make it cheaper and easier to be thin, not fat.

If the government is going to get involved, they should focus on children rather than adults, Finkelstein recommends.

He and colleague Justin Trogdon published a report this week in the American Journal of Public Health, in which they looked at different business models for the reduction of childhood obesity.

They concluded that steps to address the problem shouldn't be based on the potential for short-term financial savings.

Instead, they should look at how effective a program is at controlling weight and improving quality of life, compared to other uses for the money.

Heading off obesity during childhood in the long run saves billions of dollars of obesity-related costs during adulthood.

Marcie Calvert of Irmo, S.C., is doing her part to change her life and that of her 4-year-old daughter, Chrysa. She changed her eating habits, and in the process went from 411 pounds to 195 pounds in a little less than two years.

Her daughter now also rejects high-calorie foods in favor of more healthful ones.

"I - knew I was affecting my daughter after we blessed the food one day and she looked up and said `Lord, thank you for this protein,'" Calvert said.

Finkelstein weighed in on the issue Thursday at an obesity prevention conference in downtown Columbia, S.C.

The event, sponsored by nonprofit organization Eat Smart, Move More, South Carolina, drew about 350 people from communities, agencies and organizations around the state.

Erika Kirby of DHEC's division of Obesity Prevention and Control, who helped plan Thursday's conference, hopes attendees leave with ideas that change their communities for the better.

"Ultimately we want to make the healthiest choice the easiest choice in terms of healthy eating and active living," Kirby said.