Why Couples Who Gain Weight Together, Stay Together

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laughing couple eating french fries together

What are the best indicators of a happy and successful relationship or marriage that's built to stand the test of time?

Couple rings? Countless smiling photos of the two of you together on Facebook and Instagram? Family and friends who get along swimmingly on each and every occasion?

According to science, one of the best ways to tell if your relationship will last happily ever after is by looking at your waistlines over time.

Researchers from the Department of Psychology at Southern Methodist University[1] found that couples who report satisfaction in their marriage tend to gain weight.

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Why couples who cohabitate tend to gain weight

For a period of four years, researchers followed a group of 169 newlywed couples, checking in with them twice a year to measure factors such as height, weight, marital satisfaction, stress, and whether the couples were headed toward — or already filed for — divorce.

Their stated goal was to figure out how overall satisfaction in a marriage is reflected in each spouse's weight gain or loss over time.

"Prior research makes competing predictions regarding whether marital satisfaction is positively or negatively associated with weight gain," they explain.

The two competing theories they sought to evaluate were as follows:

  • The health regulation model, which "suggests that satisfying relationships facilitate the functions of marriage that promote health. Thus, spouses should be most likely to gain weight when either partner is less satisfied because marital strain causes stress that interferes with self-regulatory behaviors."
  • The mating market model, which "suggests that weight maintenance is motivated primarily by the desire to attract a mate. Thus, spouses should be least likely to gain weight when either partner is less satisfied because they should feel an increased need to attract a new mate. This longitudinal study of 169 newlywed couples evaluated each possibility."

The results revealed the mating marker model to be the winner, as spouses in happy marriages gained a significant amount of weight.

Another study of 8,000 people in varying stages of couplehood[2] (progressing from dating to living together to getting married) found that weight gain could also be attributed to activities like eating out, being less conscious of food choices altogether, spending time together at home on the couch and other ways of spending time that don't do any favors for one's waistline.

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For couples who don't gain weight, it may be a sign of relationship trouble.

Meanwhile, those who remained slim reported rocky marriages that eventually ended in divorce.

Unhappy couples are also a lot less likely to be going out on dates together, or eating take-out at home on the couch while binging their favorite show.

"Supporting the mating market model," the researchers found, "own and partner satisfaction were positively associated with changes in weight, and this association was mediated by steps toward divorce: Spouses who were less satisfied than usual or had partners who were less satisfied than usual were more likely to consider divorce and thus less likely to gain weight."

The researchers theorize that the phenomenon is due to an unconscious desire to continue attracting mates.

People who are part of happier couples no longer feel the need to attract a new mate and, therefore, feel less stress about their appearance.

Meanwhile, those in rocky relationships are more likely to maintain a slim figure in order to continue attracting potential new partners.

The negative impact of relationship-related weight gain on physical health

Although these happy, well-fed couples don't feel the need to worry about either their partner only loving them for their looks or potentially attracting someone new altogether, these findings do raise questions about whether stable relationships may have a negative impact on overall health and well-being.

Indeed, the second study linked "a positive association between romantic partnership and several obesity-related outcomes."

Psychologist Andrea L. Meltzer, lead researcher and then-assistant professor at Southern Methodist University in Dallas, says that couples should pay attention when it comes to their weight gain, because it can lead to health consequences such as diabetes and cardiovascular disease.

A 2017 study published in the Annual Review of Clinical Psychology[3] pointed to issues such as sleep problems and metabolic alterations, which can be a key indicator of cancer development, that are frontrunners in contributing to obesity, which is now considered a prominent health problem associated with intimate partner relationships.

In an article published in the American Journal of Epidemiology, researchers using data from 3,889 married couples over a 25-year follow-up period found that, "Having a spouse become obese nearly doubles one's risk of becoming obese."[4]

The Centers for Disease Control (CDC) notes the following risks associated with obesity:

  • All-causes of death (mortality)
  • High blood pressure (Hypertension)
  • High LDL cholesterol, low HDL cholesterol, or high levels of triglycerides (Dyslipidemia)
  • Type 2 diabetes
  • Coronary heart disease
  • Stroke
  • Gallbladder disease
  • Osteoarthritis (a breakdown of cartilage and bone within a joint)
  • Sleep apnea and breathing problems
  • Many types of cancer
  • Low quality of life
  • Mental illness such as clinical depression, anxiety, and other mental disorders
  • Body pain and difficulty with physical functioning

"So these findings suggest that people perhaps are thinking about their weight in terms of appearance rather than health," says Meltzer, now an Assistant Professor in the Department of Psychology at Florida State University.

How to fight off weight gain and maintain a happy, healthy relationship

"By focusing more on weight in terms of health implications as opposed to appearance implications, satisfied couples may be able to avoid potentially unhealthy weight gain over time in their marriages."

Researchers from the latter study with 8,000 subjects suggest introducing positive behaviors into the household and implementing them so they become a part of everyday life. That makes it easier to incorporate healthy habits into their daily routines, which many couples depend on.

There's nothing wrong with not paying as much attention to your appearance after marriage because you're confident that your spouse would continue to love you despite it.

However, your health should not be compromised, even for love.

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Caithlin Pena is a writer and editor for YourTango who enjoys books, movies, and writing fictional short stories as a hobby.