BIRMINGHAM, Alabama -- The South often gets tagged with having the most obese population.

But it doesn't appear to be true, a University of Alabama at Birmingham study suggests.

The study recently published in the journal Obesity found that there's a significantly higher percentage of obese people in a region of central and northwest states including Minnesota, Kansas and North and South Dakota.

"What we found is the West North Central region has about 41 percent obesity compared to 31 percent obesity in the southern region that includes Alabama and Mississippi," said George Howard, professor in the Department of Biostatics at UAB. "By the way, 31 percent is not a good thing -- but it's not at the bottom."

How did Southerners get such a fat reputation? Apparently because they are more truthful.

The notion that the South is the fattest comes primarily from a nationwide telephone survey done by the Centers for Disease Control, in which the surveyor asks for height and weight, among other things, Howard said.

That survey, the Behavioral Risk Factor Surveillance System (BRFSS), shows the South as the most obese, with Mississippi and Alabama, the number one and two fattest states respectively.

UAB study compared nine Census Bureau regions and found that East Souh Central was fifth, not first, in percentage of its population obese.

But the UAB researchers found that when people were actually weighed, the numbers didn't add up.

Mississippi was fourth and Alabama was in the middle of the pack, Howard said.

The numbers come from UAB's long-running REGARDS (Reasons for Geographic and Racial Differences in Stroke) study.

"We have this big REGARDS study, and we've shown there is more hypertension, diabetes and stroke in the South so we were thinking the South would have more obesity too," he said.

When the numbers didn't reflect that thinking, REGARDS researchers thought they were wrong.

"Everything said we are not the fattest but scientists are trained to think 'what did we do wrong?' "

But over time, they flipped the thinking realizing maybe they were right and there's a significant "differential misreporting" at work here, Howard said.

By comparing the BRFSS self-reported weight data with the REGARDS scale-weight data, researchers found that most everyone fudges, or underreports, their weight when asked on a telephone.

Turns out that Southerners fudge less, he said.

The study analyzed the weights in the nine geographic regions used by the U.S. Census Bureau.

It found that the West North Central region, which includes Iowa, Kansas, Minnesota, Missouri, Nebraska and North and South Dakota, ranked fourth in obesity by the telephone survey results. But when actually weighed in the REGARDS study, people from that region ranked first in the nation for obesity.

In the telephone survey results, the East South Central region, which includes Alabama, Mississippi, Tennessee and Kentucky, ranked highest. But when weighed, that southern region ranked fifth.

"It is hard to know exactly what is going on, but my speculation is that people in the South are telling the truth more," Howard said. "Perhaps there is not as much stigma connected to obesity as say someone in California, or in this case, Minnesota."

Looking at the numbers shows the wide discrepancy between what people say on the telephone and the physical evidence of actually getting weighed. When weighed in the REGARDS study, all of the regions' obesity's numbers went up -- it's just that the southern region numbers went up less.

"Everybody underreports their weight but women do it more," Howard said.

Men, on the other hand, do something else that affects the Body Mass Index, which is weight divided by height squared and is used to define obesity.

"They overreport their height, which makes them seem less obese."