This study sought to explore the relationship between weight, perceived weight, and sexual behavior among adolescent girls. In order to uncover this relationship, researchers used self-reported data from the 2005 Youth Risk Behavior Surveillance survey of 7,193 high school girls.

Researchers focused specifically on three weight indices. First researchers established participants’ body mass index (BMI) by evaluating reported weight and height. Researchers classified BMI into three subsets: girls who were in the 85th or higher percentile were classified as “overweight,” those who fell between the 5th and 85th percentile were defined as “normal,” and those below the 5th percentile were classified as “low BMI.” Along with BMI, researchers also focused on participants’ perceived weight. Perceived weight was determined by a question which asked participants to describe their weight as either, “overweight,” “underweight,” or “about right.” The third weight index was weight misperception, which was determined by comparing BMI and perceived weight. Girls whose perceived weight matched their BMI were classified as “accurately estimating their weight.” When girls described themselves as “underweight” but in fact had a normal or high BMI they were classified with “underweight misperceptions.” And lastly, when a girl perceived herself to be “overweight” but had a low or normal BMI she was classified with “overweight misperceptions.”

Along with the three described weight indices, researchers also looked at six sexual behaviors: having ever had vaginal sex, age at first sex, total number of sexual partners, alcohol use at last sex, condom use at last sex, and oral contraceptive use at last sex. Age at first sex was defined as either “sex before age 13” or “sex at or above age 13.” The total number of sexual partners was defined as either “four or more” partners or “fewer than four” partners.

Researchers used statistical analysis to uncover the relationship between these variables.

Key Findings:

There were no differences in the likelihood of ever having sex based on BMI or whether a girl’s perception of her own weight was accurate.

Girls who perceived themselves as overweight, however, were less likely to report ever having sex.

Sexually active girls who were in fact, or perceived themselves to be at the weight extremes, along with the girls with weight misperceptions were more likely to report sex before age 13, having four or more partners, or not using condoms at last sex than girls with normal weight and with perceptions that their weight was “just right.”

Sexually active girls with low BMI were less likely to report condom use than girls with a normal BMI.

Sexually active girls who perceived themselves as overweight were 1.6 times more likely to report having first had sex before the age of 13 and were less likely to report condom use compared to girls who perceived their weight as normal.

Sexually active girls with overweight misperceptions were also less likely to report condom use that those who had an accurate estimation of their weight.

Among White girls, there were no significant associations between BMI or perceived weight and sexual behavior; however, there were associations between weight misperceptions and sexual behavior.

oThose with underweight misperceptions were more likely to report ever having had sex

and had almost twice the odds of reporting four or more sexual partners.

oThose with overweight misperceptions were half as likely to report condom use as

compared to girls with accurate weight perceptions.

Among Black girls, there were significant associations between both BMI and perceived weight and sexual behaviors but no association with weight misperceptions.

oThose who were sexually active with a low BMI were less likely to report condom use

than girls with a normal BMI.

oThose who perceive themselves as overweight had 1.5 times the likelihood of reporting

four or more sexual partners than girls who perceive their weight as just right.

Among Latina girls, there were associations between all of the three weight indices and sexual behaviors.

oThose who were sexually active and overweight had 2.6 times the likelihood of having

had sex before the age of 13.

oAt the same time, those with a low BMI had 12 times the odds of having had four or more

sexual partners.

oSexually active girls with underweight misperceptions had more than three times the

likelihood of having sexual debut before the age of 13.

oWeight seems to influence sexual behavior more for Latinas than for Black or White girls.

Black and Latina girls were more likely to have underweight misperceptions as compared to White girls.

SIECUS Analysis:

The relationship between body image and sexual behavior is particularly under-researched and this new study adds quite a bit to our understanding of how these variables interact. The addition of variables that measured young women’s perception of their own weight revealed that in many cases how a young woman perceives her weight may be more important than her actual weight, in terms of her ability to negotiate sexual situations. Similarly, the analysis based on race, suggests that body image significantly influences young women’s sexual behavior across races, but that differing cultural values about body size and shape may also factor into differences between White, Latino, and Black adolescents.

SIECUS believes it is absolutely necessary that culturally competent discussions of body size, body image, and race be included in comprehensive sex education. Our Guidelines for Comprehensive Sexuality Education, K-12, include a number of messages about body image, such as: “Standards of beauty change over time and differ among cultures”; “The size and shape of a person’s body may affect how others feel about and behave toward that person”; and “Many people of all shapes, sizes, and abilities have a positive image of their bodies.”

In the current political and educational climate of budget cuts, standardized tests, and evidenced-based programs, many sexuality education programs are being whittled down to STD/HIV and unintended pregnancy prevention. However, this research demonstrates that someone’s ability to negotiate a sexual situation or condom use is ultimately dependent on a multitude of factors beyond whether they simply understand the correct use of birth control or a condom. This research stands as a warning that the topics of STD/HIV and unintended pregnancy prevention cannot be separated out from broader comprehensive sex education.