I haven't been reading this group lately, but I can across this article and thought I would post it here.
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.
Unfortunately, there isn't enough information in the article to know if the study has any validity. I don't what they considered "overweight" or not, if sexual attractiveness has anything to with it, or if the cause and effect is the reverse of what they seem to imply (women who have had sex or more likely to have been pregnant ). Also, sexual behavior is effected by hormones (adipose tissue has endocrine functions, including the modulation of estrogen, and extremely underweight women lose their sexual functioning). Neurotransmitters may also be a factor. Although I'm probably over-thinking this, as afaik, this study could be completely worthless.