It's true that having a workout buddy is the best thing ever—you'll work harder, try new things, and simply enjoy exercising more. But it turns out when you apply the same accountability to a diet, having a partner may actually harm your health, according to a new study in the Journal of Health Psychology. When female roommates both dieted, the pairs reported more anxiety, depression, and disordered eating compared to when one roomie watched what she ate and the other noshed as she normally would. What's more, the women on a joint diet didn't lose notably more weight than friends who ate as they normally would together—less than one pound to be exact.
Hold up. Enlisting your girls to help you get healthy seems like a great way to have support, hold yourselves accountable, and keep up the motivation. So what gives? It's possible the co-dieting could have led to something called "stress transmission," says study author Angela Incollingo Rodriguez, health psychology Ph.D. candidate at UCLA. When someone you're close to is stressed or depressed—in this case, potentially overthinking every bite that goes into her mouth—those negative emotions could rub off on you.
Plus, if your roommate is focused on her own diet and feelings, she might not be able to offer the support you need or expect from the joint commitment. And, instead of instilling motivation and accountability, dieting alongside a friend who has different willpower and a different body may create competitiveness and resentment, says Rodriguez. Bummer—not exactly what you had hoped for, right?
This all sounds like the worst aspects of sisterhood, so are these dieting dynamics exclusive to female roommates or friends? Research does show that women tend to be more susceptible to stress transmission than men, says Rodriguez, so, in theory, a dude diet buddy might be better than your female roomie. But no matter who you decide to partner up with—a romantic partner, roomie, or a family member—there is still the potential for competitiveness, which can either be a motivating factor or can add a layer of stress.
On the flip side, a study in JAMA Internal Medicine found that when one partner in a cohabiting couple made a healthy behavior change, such as quitting smoking or exercising more, the other was more likely to follow suit. Essentially, one partner was the catalyst for positive change that might not have happened otherwise.
So don't write off that accountability partner idea just yet. "When changing your eating habits, having as much support and encouragement as possible is always great," says New York–based nutritionist Brigitte Zeitlin, R.D. Whether it's your friend, your S.O., or your roommate, the key is picking the right person for the job—here's how:
Ask your healthiest friend for help. According to the study, your best bet is finding a supportive partner who is not dieting. Enlist your one friend who orders the salmon at dinner but never complains about needing to lose weight. She probably has a great perspective on how to balance being healthy and living life, and since her goals aren't the same as yours, there's low likelihood of either competitiveness or judgment.
Look for a track record of unconditional support. If you want to clean up your eating habits together but your friend is the liquid calories police, it can quickly start to feel like judgment even if that wasn't her intention, says Zeitlin. Pick someone you know will encourage you no matter what—including when you *need* a second glass of happy hour wine after that presentation at work didn't go so well.
Consider where you need help most. "A huge factor here is knowing what you need to reach your goals," says Zeitlin. If getting your butt to the gym is the biggest obstacle standing between you and your target weight, consider downgrading the diet focus to just a food journal but having a girlfriend be your workout buddy instead.