Most of us have heard that body weight can influence health, but far less attention has been paid to the ways it can influence romantic partnership. In our new article in Social Forces, we followed more than two thousand older adults over five years to see whether body size relates to having a partner and partnered sexual activities.

The study relies on the National Social Life, Health, and Aging Project, a nationally representative survey that includes anthropometric measures of weight and height while also recording the interviewers’ rating of each respondent’s body shape on a five‑point scale from very thin to obese. Those two indicators overlap only modestly, meaning we may pull apart two routes by which body size can matter: the functional component of mobility and comfort captured by Body Mass Index (BMI) and the component of social evaluation captured by the interviewers’ rating.

When we looked five years down the road, body size clearly shaped people’s chances of having a partner, but it did so in different ways for men and women. Women who were described by interviewers as carrying more weight were less likely than women described as slimmer to be married, cohabiting, or in a steady dating relationship. The same pattern appeared—though a little more modestly—for BMI independent of the visual rating. Men, in contrast, showed no significant drop in the probabilities of having a partner as body size increased. These patterns held after we adjusted for age, education, and race, suggesting that the impressions tied to body size play a role independent of social background.

Among those partnered, the patterns of body size remain for partnered sex. Women at the upper end of the BMI range reported fewer occasions of vaginal intercourse in the past year, fewer experiences of genital touching and oral sex, and were more likely to say there had been several months when sex simply was not pleasurable. Men’s reports varied little across the body size spectrum and occasionally ticked upward. Solitary sexual activities told another story. How often people thought about sex and how often they masturbated showed no link to either BMI or the visual rating for men or women. When no partner’s eyes are involved, the influence of body size seems to fade.

At least two possible mechanisms could explain how size leads to these outcomes, and we tested each of them in the research just published in this paper. The first mechanism concerns attractiveness. Because the same interviewers who rated body shape also gave each respondent an overall attractiveness score, we could see whether attractiveness associated with different body shape mediate its association with partnership or sexual activity. Our results show that the negative associations of rated body shape with having a partner and engaging in partnered sex were mostly explained by the differences in the attractiveness scores. This mechanism mattered a lot for women and their access to intimate sexual activity. For men, attractiveness explained their patterns between body shape and finding sex not pleasurable and engaging in any sexual activity.

The second mechanism concerns comfort and mobility. The survey asked whether respondents had trouble walking one block, walking across a room, dressing, bathing, eating, such as cutting up food, getting in or out of bed, and using the toilet. Higher BMI predicted a higher count of such limitations for men and women alike. These limitations partially explained connection between high BMI and both men and women’s reports that sex had not been pleasurable. They did not explain the lower odds of having a partner or smaller number of sexual encounters, which points back to the importance of social impressions.

These evidence of social patterning matter for everyday life because partnership shapes so many other outcomes: household income, caregiving arrangements, emotional support, and shared decision‑making. When the chances of partnership and satisfying sex shift with body size, other parts of family life shift as well. Health guidelines and research often present BMI as a personal health indicator. The patterns we see remind us that body size also carries social meaning, and that meaning can open or close doors.

Body size is far more than a health statistic. It is part of a social script that guides who meets, who matches, and how intimacy unfolds, and that script reads differently for men and for women. Recognizing both the perception side and the functional side of body shape can help individuals, clinicians, educators, and media creators open more pathways to lasting partnerships and satisfying intimate sexual activities for people of every shape.

Yiang Li is a PhD student in Sociology at the University of Chicago. He is also a predoctoral trainee in the NIA T32 Program in the Demography and Economics of Aging at the Center on Healthy Aging Behaviors and Longitudinal Investigations and a student affiliate at the Stone Center for Research on Wealth Inequality and Mobility at the University of Chicago. His research focuses broadly on social demography, health, family, neighborhood, and aging. You can follow Yiang Li on bluesky @yiangli.bsky.social and learn more about him on his website.

Linda J. Waite is the George Herbert Mead Distinguished Service Professor of Sociology and Senior Fellow at NORC at the University of Chicago. Her research interests include social demography, aging, the family, health, sexuality, and social well-being. She is the Principal Investigator of the NIA-funded National Social Life, Health, and Aging Project. Waite is the recipient of a MERIT Award from the NIA and an elected member of the American Academy of Arts and Sciences.