It’s been said that couples have a way of mimicking each other over time. In a study conducted in 1987, researchers found that people in long-term relationships begin to take on their partner’s physical attributes as a result of occupying the same environments, engaging in the same activities, and eating the same food.
Now a new study published in the Atherosclerosis journal posits that the similarities may go beyond just the physical. The authors say that when couples stay together long enough their bodies begin to synchronize on a “deep biological level” — influencing each other’s physical activity and overall health.
The trend has been observed in different cultures
The new paper was derived from health data from 5,391 Japanese couples and 28,262 Dutch couples. Long-term partners from both populations exhibited similar levels of blood pressure, triglycerides (the type of fat found in the blood), and cholesterol.
They were also more likely to simultaneously suffer from chronic diseases like diabetes and hypertension. These outcomes — observed in both the Japanese and Dutch participants, as well as Indian participants from the 1987 study — were also found among a group of Americans from a study published in 2016.
The research was conducted by a team from the University of Michigan at Ann Arbor that reviewed data from 1,568 older U.S couples. Partners who had been together for more than 50 years had roughly equivalent kidney function and grip strength.
“Aging is something that couples do together,” explained Shannon Meijia, a postdoctoral research fellow at the University of Michigan, in a 2016 interview with NPR. “You’re in an environment together, you’re appraising that environment together, and making decisions.”
Another study from the University of British Columbia found that couples in long-term relationships tended to experience concurrent symptoms of psychological illnesses like depression.
In all of these studies, even couples who were genetically dissimilar exhibited this health phenomenon. The researchers refer to this as “assertive mating” — a term that describes the tendency for organisms with similar underlying physical characteristics to couple up.
Given that similarities were observed among genetically dissimilar couples, lifestyle factors likely explain the phenomenon.
How your partner can influence your health
Many of the health similarities observed in long-term couples were preceded by behavioral similarities, namely diet and degree of physical activity.
These two factors alone have a major impact on one’s disease risk.
In a study published in the Journal of Social Sciences participants gravitated towards the exercise behaviors of those around them. A study published in the journal Obesity found that overweight people tend to lose more weight if they spend time with their fit partners and friends. The more time they spent with these people, the more weight they lost.
It follows that there are other behavioral habits that contribute to healthier lifestyles for long-term couples.
“Working out with a crowd carries a plethora of intertwined benefits that include enhancing consistency, duration, motivation, conversation and inspiration,” says Dian Griesel, Ph.D., co-author of TurboCharged and president of public relations firm DGI. “Workouts with others improve consistency because they involve a commitment. ‘No shows’ and cancellations get noticed by others and positive peer pressure can help curtail the urges to skip a workout … or quit.”