Can being in a relationship make you gain weight?

When you are in a steady relationship, do you tend to let yourself go?  That is, do you stop brushing your hair and/or teeth and skip the gym more than you used to?  Or are you the kind of person who continues to take care of your appearance and physical health no matter who you are in a relationship with or what stage of the relationship you’re in?  If you agreed with the latter, you could be in the minority.

There’s a common notion that people in relationships can (and do) let themselves go.  Researchers who study this idea call it the “marriage market hypothesis” (e.g., Ortega et al., 2010).  The idea is that single people (people in the market for a date or marriage) need to look good and be physically fit in order to attract a mate.  Once they are in a relationship or even married, the pressure to be more attractive subsides.  And if you return to the dating game after a breakup or divorce, then you get back to presenting your most attractive self.

There is actually some support for this idea, although the evidence is a bit inconsistent.  For example, in one study tracking Americans across a 10 year span, single women who got married within the 10 year span gained more weight compared to those who were already married at the beginning of the study and remained married (Sobal, Rauschenbach, & Frongillo, 2003).  The same study found that divorced men and recently widowed men were more likely to lose weight.   

In another study, fitness levels (measured by endurance on a treadmill test) were reduced in men who got married (Ortega et al., 2010).  For men who divorced, fitness levels increased slightly but declined if they remarried.  For women, fitness increased for women who stayed single.

Is it about finding a mate or is it something more?

Although these studies statistically controlled for many factors (like age and income) that influence weight and fitness, there may be a few other social reasons that may help explain why this occurs.  For example, time constraints increase for people in relationships – instead of making decisions as individuals, couples consider their partner’s needs when making decisions about leisure activities and may less often agree.  There is also family to consider.  Since couples often have children after marriage, weight gain and inactivity in these studies may be caused by less time and resources dedicated to exercise and grooming.  Finally, there is stress caused by major life transitions, like starting a new relationship or getting a divorce, that may have some impact on weight gain and inactivity. 

There is also something to be said for getting into a relationship where you are relaxed and comfortable with one another.  That is, appreciated no matter what you look like or if you’re carrying a few extra pounds.  It might not just be vanity or mate attraction that causes people to lose weight and look better when dating but other social factors that cause people to gain weight or let themselves go when in a relationship.    

Further Reading:

Ortega, F., Brown, W., Lee, D., Baruth, M., Sui, X., & Blair, S. (2010). In fitness and health? A prospective study of changes in marital status and fitness in men and women American Journal of Epidemiology, 173 (3), 337-344 DOI: 10.1093/aje/kwq362

Sobal, J., Rauschenbach, B., & Frongillo, E. (2003). Marital status changes and body weight changes: A US longitudinal analysis Social Science & Medicine, 56 (7), 1543-1555 DOI: 10.1016/S0277-9536(02)00155-7