You vowed to love each other for richer or poorer, in sickness and in health. But no one said anything about the happy weight gain. Here's how to stop married life from going straight to your hips.

By Alexa Joy Sherman

You've heard that husbands and wives begin to look alike, but the real resemblance may be in the extra padding both spouses start to add on. According to a study in the American Journal of Human Biology, married people are more likely to be overweight than single people—and the older they get, the more weight they gain. So why is weight gain after marriage so common, and what can you do to defy the odds? Read on for the expert lowdown on this happy weight gain, plus tips for how to lose weight after marriage.

4 Causes for Weight Gain After Marriage, Plus Solutions to Slim Down

  1. You share everything.

Being equal partners in life may be a beautiful thing, but not when you eat the same heaping helpings as your hubby. Men have more muscle mass than women (even if they weigh the same amount), and can therefore consume more calories without gaining weight. This factor puts women more at-risk for weight gain after marriage. "The extra muscle helps men burn more energy, even at rest," explains Cynthia Sass, R.D., coauthor of Your Diet Is Driving Me Crazy: When Food Conflicts Get in the Way of Your Love Life. While a moderately active, 180-pound male can eat about 3,050 calories a day and not gain weight, his moderately active 145-pound wife can consume only about 2,235. (Check out these metabolism-boosting foods and workouts to stoke your calorie-burning furnace.)

Happy Weight Gain Rx: Use a few tricks to trim calories from dinner: Make up your plate yourself so he doesn't give you a supersize helping, and do it in the kitchen rather than from serving dishes at the table. This way you won't be tempted to graze once you've finished. To make your plate look just as full as your hubby's for a fraction of the calories, double up on low-cal foods like steamed veggies and take half as much in carbs, such as potatoes, rice, and pasta. (Then keep these 10 fat-fighting secrets in mind.)

  1. He loves you—no matter what size you wear.

It's no coincidence that research shows that the longer people are married, the more pounds they pack on. Each wedding anniversary gives you a little extra assurance that your man isn't going anywhere, so why not let yourself go, right?

Happy Weight Gain Rx: Take stock of what you've lost due to the weight gain after marriage. Think about the toll on your relationship. "Weight gain can cause health problems, decreased sex drive, and body-image issues," says Sass. And consider your future. "Don't you want to enjoy your retirement together rather than spend it taking several medications a day?" asks David L. Katz, M.D., director of the Prevention Research Center at Yale Medical School.

  1. You're a dine-out couple.

For most busy couples—especially those with children—restaurants and take-out fare are a major sanity saver. But you tend to indulge significantly more when you order from a restaurant than you do when you cook for yourself (to the tune of about 30 percent more calories).

Happy Weight Gain Rx: Limit restaurant visits and overhaul your orders. Eat out only once a week and order carefully, suggests Megan A. McCrory, Ph.D., a research associate professor in nutrition at Boston University. At a Mexican restaurant, start with gazpacho and share chicken fajitas with your husband (go heavy on low-calorie salsa and easy on sour cream and guacamole). Pondering pizza? Order a side salad with light dressing, and limit yourself to one slice of thin-crust with lots of veggies. With Japanese cuisine, have miso soup followed by one or two sushi rolls (one roll has six pieces). Stick to plain fish and veggie rolls that don't contain mayo, cream cheese, or fried ingredients (and watch out for "new wave" rolls with fatty meats like beef, sausage, and duck). Sashimi, which is just fish, is always a safe bet. If you order an entree at a typical American restaurant, ask your waiter to wrap up half your meal before it's served and take it home, suggests Dr. Katz. Then have it for lunch the next day. (Steer clear of the most unhealthy restaurant meals in the country.)

  1. You've become less active.

Between kids, career, and keeping the home fires burning, it's no surprise that plenty of couples spend most evenings and weekends collapsing—or cozying up—on the couch together. Blame it on the TV: A recent study in the journal Preventing Chronic Disease found that adults who watch more than two hours of TV a day are more likely to be overweight or obese—weighing 9 pounds more and consuming an additional 150 calories a day, on average—than people who watch less than one hour daily. (Teens aren’t the only ones who fall victim to too much TV time.)

Happy Weight Gain Rx: Start a new healthy habit: Before dinner, rev yourself up with some activity and try to involve your spouse and kids as much as possible: Ride bikes, play Frisbee, walk in the park, or go in-line skating. Then eat together as a family without any distractions, making a conscious effort to focus on the flavors of the food and one another's company. Finally, vow to eat only in designated dining areas (the couch shouldn't be one of them!) and limit television time as much as possible. "There is no magic number, but in general, aim for two hours max a day," recommends Dr. Katz.

Tempted by the Food of Another

Your husband isn't the only one keeping you from your get-fit goals. Here are Dr. Katz's tips for how to keep calories under control when you're around these common food pushers:

  • The generous coworker. Sidestep the kindhearted colleague who keeps a candy dish on her desk by bringing healthy snacks like baby carrots, Greek yogurt, and fresh fruit. Explain to her that you're trying to eat nutritious foods, and ask that she not offer you treats.
  • The snack-happy kids. If you pick at your kids' treats, strive to bring less tempting stuff into the home — without depriving them. "Choose the most nutritious food in every category, including crackers and cookies," says Dr. Katz, who keeps his kids happy with low-calorie Guiltless Gourmet chips and Newman-Os cookies. You'll be less likely to overeat—and even if you do, it won't be as much of a dietary disaster. (Are you snacking all wrong?)

The smothering mother. No matter how old you get, Mom may still feel the need to feed you. If it's affecting your weight, have a heart-to-heart with her and explain why eating healthier is important to you. Pose it as a plea for help and she'll be more likely to stop insisting you clean your plate.