The study is based on data from the 2002 National Survey of Family Growth, which looked at sexual behavior of more than 7,000 U.S. women.

Dr. Bliss Kaneshiro of the School of Medicine at the University of Hawaii and Oregon State University professor Marie Harvey studied the relationship between body mass index and sexual behavior -- including sexual orientation, age at first intercourse, number of partners and frequency of sexual intercourse.

The study, published in Obstetrics & Gynecology, contradicted widely held stereotypes that overweight and obese women are not as sexually active as other women. If anything, the researchers concluded the opposite seems to be true.

"These results were unexpected and we don't really know why this is the case," Kaneshiro said in a statement.

Ninety-two percent of overweight women reported having a history of sexual intercourse with a man, as opposed to 87 percent of women with a normal body mass index.

"This study indicates that all women deserve diligence in counseling on unintended pregnancy and sexually transmitted disease prevention, regardless of body mass index," Kaneshiro said.