IOWA CITY (AP) - More University of Iowa students are binge drinking in the two years since this college town enacted laws limiting the amount of alcohol bars can serve, according to a study by an alcoholism expert.

Three of every four undergraduates surveyed this year could be called binge drinkers, said the study by Peter Nathan, an alcoholism expert at the university.

Nathan and graduate clinical psychology student Sara Dhuse interviewed 353 undergraduate students for the study, which showed the rate of binge drinking jumped from 69 percent in a 1997-2001 study - before the drinking limits took effect - to 75 percent since the law was enacted.

Researchers define binge drinkers as men having five or more drinks in one sitting or women having four or more drinks in one sitting at least once in two weeks. Frequent binge drinkers followed that pattern at least three times in the previous two weeks.

The study showed that two of every five surveyed is a frequent binge drinker.

That is down from the earlier study but alarming nonetheless, said Nathan, a professor of psychology and of community and behavioral health.

In 2001, the Iowa City Council voted to prohibit bars from using incentives such as drink specials and selling more than two servings of alcohol to one person at a time.

Nathan said allowing only people 19 and older into bars under a new law that takes effect Aug. 1 will keep only a small number of college students out.

"Despite all these efforts … or maybe because of them … students are drinking as much as ever," Nathan said. "And they're bingeing a little more than ever."

The study's numbers don't surprise Leah Cohen, owner of Bo-James restaurant in downtown Iowa City.

She said a major problem is young people loading up with shots of alcohol to get drunk before going to bars.

"These kids are not learning to sit down and have a beer, and relax over a beer," said Cohen, who switched to a 21-and-older bar last year.

Carolyn Cavitt is co-director of the University of Iowa's Stepping Up Project which was created to curb abusive student drinking. She said the environment for drinking needs to change.

"I think that the change is happening, but it's been slow," she said.