CHICAGO - Diets high in protein may be the best way to keep hunger in check, U.S. researchers said in a study that offers insight into how diets work.

They found that protein does the best job at keeping a hunger hormone in check, while carbohydrates and fats may well deserve their current nasty reputation.

The study, which will appear in the Journal of Clinical Endocrinology & Metabolism, looked at the effectiveness of different nutrients at suppressing ghrelin, a hormone secreted by the stomach that stimulates appetite.

"Suppression of ghrelin is one of the ways that you lose your appetite as you begin to eat and become sated," said Dr. David Cummings of the University of Washington in Seattle, who worked on the study.

The researchers gave 16 people three different beverages, each with varying levels of carbohydrates, fats, and proteins. They took blood samples before the first beverage, then every 20 minutes for six hours afterward, measuring ghrelin levels in each sample.

"The interesting findings were that fats suppress ghrelin quite poorly," Cummings said in a telephone interview. They fared the poorest overall.

"Proteins were the best suppressor of ghrelin in terms of the combination of the depth and duration of suppression," he said. "That is truly satisfying because high proteins are essentially common to almost all of the popular diets."

They also found that eating carbohydrates resulted in a strong ghrelin suppression at first, but ghrelin levels rebounded with a vengeance, rising to an even higher level.

Basically, the carbohydrates eventually made people even hungrier than before they had eaten.

Cummings said the findings may aid in future research on the effectiveness of different diets.

And the study likely means that nightly bowl of ice cream is out. "That is a bad idea no matter what," he said.

(Editing by Jackie Frank)