Moving in together may take your relationship to the next level, but it can also bump up that number on the scale. Theresa, 26, was svelte when she and her boyfriend, Rosario, put their names on the same mailbox, but things soon changed. "I ate whenever he did, even if I was stuffed," she says. Theresa ignored her expanding waistline until she saw a shocking photo. "It looked like I had three stomachs!" she exclaims. And she was equally stunned when, eight months after moving in together, she had gained 40 pounds. Theresa’s not the only one to fall victim to "love lard" (the weight gain that often accompanies falling head over heels). Last April, researchers at Newcastle University looked at studies that examined the eating habits of over 12,000 cohabitating or married couples in Europe, North America, and Australia. In a trend called "dietary convergence," they found that after a twosome begins to cohabitate, women start consuming more junk , while men’s diets tend to improve. But why do we pork out when we pair up? "Your guy has food that you’d never bring in your house," says dietitian Lisa Young, PhD, author of The Portion Teller Plan . "But half the battle is recognizing that this could be a problem and being proactive about it." Read on to get the skinny on the most common weight issues—and how to keep them at bay. PLATE ENVY Problem: Matching him bite-for-bite. "A few extra cookies a day equals a 10-pound weight gain over the course of a year," cautions Linda Spangle, RN, author of 100 Days of Weight Loss . Tamara, 34, can attest to that. "When I moved in with Mike, my portions got much larger in an attempt to match his," she says, and was amazed when she grew from size 8 to 14. Solution: Downsize your dish. A 2007 University of Calgary study found that 17 percent of research participants who used a "diet plate," which demarcates healthy portions, lost 5 percent or more of their body weight. Tamara devised a similar strategy. "When Mike reached for a dinner plate, I went for a salad plate, so I couldn’t fit as much food," she says. Within six months, she was 50 pounds lighter—and just as much in love. THAT’S EATER-TAINMENT! Problem: Food-centered love. Our together time often revolves around eating—whether it’s a lavish dinner out, or Grey’s Anatomy and a pint of Ben & Jerry’s. You’ve got to eat; the danger is making it your main source of fun. Solution: Cook as a couple. Concentrate on meal creation rather than consumption. "My fiancé , Mike, and I ate out at least three times a week," says Ranee, 32, who blames gaining three sizes on cohabitation. "Now we cook together four nights a week." The switch helped the couple lose over 60 pounds collectively. Tip: You can find more than 950 low-fat recipes covering every course at 3fatchicks.com. MIDNIGHT SPECIAL Problem: Late-night snacking. His Letterman habit could actually make you heavier. Women have a tendency to snack throughout the day, says Spangle, whereas men nibble at night. But by indulging his snack attacks and yours, you may, in time, unwittingly gain weight. Solution: Call it a night. Turning in just an hour earlier could help you stave off pounds. Research from Université Laval in Quebec City found that sleeping may increase production of leptin, a hunger-suppressing hormone. Researchers found that people who slept 6 to 7 hours a night were an average of 11 pounds plumper than those who snoozed for 7 to 8 hours.
