VoxEU Column Health Economics

Overweight adolescents and risky sexual behaviour

Obesity and teenage sex have become social and public health issues in developed countries. This column looks at the effects of being overweight on attitudes to sex among teenage girls in the US. While obesity is associated with less vaginal intercourse, overweight teenage girls are at least 15% more likely to have had anal sex, with a high chance of sexually transmitted disease.

Obesity has become a pressing public health issue in the US and most other developed countries, and increasingly in developing countries. Teenage girls have not been spared; between the 1960s and 2003-2005, the prevalence of obesity in girls aged 12 to 19 in the US increased from 4.7% to over 17% (National Centre for Health Statistics 2010).

Recent studies in the economics literature have considered the effects of obesity on the sexual behaviour of teenage girls, which is viewed through a lens of assortative mating in a market for sexual partners. The working hypothesis has been that as an aspect of physical appearance, being overweight may be a liability in the adolescent dating market.

These studies have found that girls who are overweight or obese are more likely than their recommended-weight peers to delay engaging in sexual intercourse (Cawley et al. Sobal 2006 and Sabia and Rees 2010). While this is an interesting and important finding, initiating sexual intercourse may not be the most significant sexual behaviour to study from a public health standpoint.

Recent evidence from the Centres for Disease Control indicates that 1 in 4 young women between the ages of 14 and 19 in the US is infected with at least one of the most common sexually transmitted diseases (STDs) – human papillomavirus (HPV), chlamydia, herpes simplex virus, and trichomoniasis (CDC 2010). Given the high prevalence and public health importance of STDs, the importance of peer networks in adolescents’ lives, and economic theory suggesting that girls who are perceived (or perceive themselves) as less attractive will be willing to incur greater risks in order to attract a partner. Boys, according to this line of thinking, would move to less physically attractive matches in order to find willing partners for risky sex. A focus on risky sexual behaviour – as opposed to any sexual intercourse – thus seems warranted.

In recent research (Averett et al. 2010), we use data from The National Longitudinal Survey of Adolescent Health to investigate effects of adolescent girls’ obesity on their propensity to engage in risky sexual behaviour. We use a variety of econometric techniques, considering both absolute weight and weight relative to other girls in the individual’s school, and considered three different behaviours that place girls at risk for contracting STDs – vaginal intercourse without a condom, sex while under the influence of alcohol, and anal intercourse. To put the last behaviour in context, recent figures indicate that 11% of adolescent girls age 15-19 in the US in 2002 had ever engaged in anal sex (Lindberg et al. 2008), a behaviour that is associated with high STD risk among young heterosexual women (Jenness et al. 2003).

Our findings confirm previous research indicating that overweight or obese girls are less likely to be sexually active than other girls. The authors also found that as a result of being less sexually active, overweight or obese girls are less likely to have vaginal intercourse without a condom. However, overweight or obese girls are not less likely to have sex under the influence of alcohol, and once they have had vaginal intercourse, their consistency of condom use is no different from that of their recommended-weight peers. Our most striking finding however, is that overweight or obese girls are at least 15% more likely than their recommended-weight peers to have had anal intercourse.

These findings make clear the importance of going beyond the question of just any sexual intercourse when characterising the sexual behaviour of teenage girls. Our findings also illustrate the benefits of using multifaceted and contemporary measures of risky sexual behaviour. If we had only considered outcomes related to vaginal intercourse, we would have concluded that overweight and obese girls are less likely than their recommended-weight peers to engage in risky sexual behaviour.

By considering heterosexual anal intercourse – a risky behaviour that is on the rise both in the general population and among teens (Mosher et al. 2005, Lescano et al. 2009) – our conclusions are very different. Our article contributes to the growing literature on the consequences of body weight by identifying a behavioural source of health risk resulting from overweight relatively early in the life – risky sexual behaviour among adolescent girls. Our findings underscore the urgency of both stemming the tide of the obesity epidemic and educating teenagers about safe sex.


Averett, S, H Corman, and N Reichman (2010), “Effects of Overweight on Risky Sexual Behaviour of Adolescent Girls”, NBER working paper 16172.
Cawley, J, K Joyner, and J Sobal (2006), “Size Matters: The Influence of Adolescents’ Weight and Height on Dating and Sex”, Rationality and Society, 18:67-94.
Centres for Disease Control (2010), Press Release, 11 March 2008.
Jenness, SM, EM Begier, A Neaigus, CS Murrill, T Wendel, and H Hagan (2010), “Unprotected Anal Intercourse and Sexually Transmitted Diseases in High-Risk Heterosexual Women”, American Journal of Public Health, 17 June.
Lindberg, L, R Jones, and J Santelli (2008), “Non-Coital Sexual Activities Among Adolescents”, Journal of Adolescent Health, 43(3):231-238.
Mosher, WD, A Chandra, and J Jones (2005), “Sexual Behaviour and Selected Health Measures: Men and Women 15–44 Years of Age, US, 2002”, Advance Data from Vital and Health Statistics, 362.
Lescano, C, CD Houck, LK Brown, G Doherty, RJ DiClemente, MI Fernandez, D Pugatch, WE Schlenger, and BJ Silver (2009), “Correlates of Heterosexual Anal Intercourse Among At-Risk Adolescents and Young Adults”, American Journal of Public Health 99(6):1131-1136.
National Centre for Health Statistics (2010), Health US, Hyattsville, MD.
Sabia, J and D Rees (2010), “The Effect of Body Weight on Adolescent Sexual Activity”, Unpublished working paper.

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