Have your clothes gotten tighter since you tied the knot? Blame your spouse, not the dryer, suggests a new study presented at the Society for Personality and Social Psychology annual meeting in New Orleans. When researchers followed 169 recently married couples for more than four years, they found that spouses who were more satisfied with their union tended to gain more weight, and spouses who were less satisfied, tended to gain less weight.

"For each unit of increase in satisfaction found, either by the person or the partner, a 0.12 increase in BMI occurred every six months, on average," Meltzer said. For example, a woman who is 5-foot-4 and 120 pounds has a BMI of 20.6. If she gains a half pound, her BMI would increase to about 20.7. "At the end of the four-year study, they [on average] are still in a healthy weight range," Meltzer noted. "But we don't know what happens after four years yet." The correlation held true for both genders, so what's driving the it?

Unhappy newlyweds could be considering divorce and are therefore trying to maintain an ideal weight to attract a new mate, says lead researcher Andrea Meltzer, PhD, assistant professor of psychology and a social psychologist at Southern Methodist University, in Dallas. Those who are satisfied may loosen the reigns on weight control knowing the search for a mate is over.

Charlotte Markey, PhD, associate professor of psychology at Rutgers University, in New Jersey, offered another explanation. "It is also possible that happily married couples see each other more and eat together more [dining in the company of others can lead people to eat more]." In a separate study presented at the same meeting, Markey found that heterosexual and lesbian couples tend to compare themselves to their partner when making judgments about their own weight. "This is pretty intuitive, but never documented," she said. "People in relationships seem to be comparing themselves to their partners, and those comparisons seem to shape how they feel about their weight and their body."

If you’re in a new marriage, keep health issues, like weight maintenance, part of the conversation, suggests Markey. Talk about how you can both eat healthy and stay physically active. Here are a few ideas:

Display Your Fittest Pics: Sometimes all it takes to motivate you is seeing how fit you were or remembering how invigorated you felt at a certain time,” says Wendy Bazilian, DrPH, RD, who shares a holistic practice with her husband in San Diego, California. Displaying photos of you being active as a couple acts as a constant reminder of how you plan to live your life together.

Keep a Couple’s Calendar: A calendar offers more than just inspiration to plan ahead–a crucial habit for healthy eating and making time for fitness (and each other). It’s also a great place to keep track of daily and weekly goals. Turn your calendar into a weight loss tool by color-coding different types of activities. Keep track of mealtimes using a green marker, exercise and opportunities to be active with a red marker, work and other obligations in blue marker. This is a visual reminder to make sure you have a balanced week that incorporates both work and play.

Accept Your Dietary Differences: Sharing is caring, but it’s unlikely the two of you need the same calorie counts to lose or maintain your weight. “As a couple the tendency is to want to split everything even-stephen,” says Jason Bazilian, Wendy’s husband and a doctor of acupuncture and oriental medicine. “But if you just nudge the knife over a tiny bit to make more appropriate portion sizes, you’ll be closer to achieving your goals.”

For more tips, check out How to Lose Weight as a Couple.