The Buddy Contract
To help ensure that both you and your buddy get what you bargained for, consider writing up a "buddy contract" -- a document that spells out your mutual goals and the ways you plan to help each other achieve them.
Be sure to include both short-term goals ("I want to get to the gym three times a week and I need you to go with me") and long-term ones -- such as how much weight you'd like to lose, or how many miles you'd eventually like to walk each week.
"The goals should be firm, but the ways to accomplish them should be flexible, to accommodate what you learn about yourselves and each other along the way," says Shafran.
He suggests that both buddies keep a copy of the agreement and re-read it often, reminding each other of what you're each trying to accomplish.
At the same time, don't be afraid to call it quits when a diet buddy isn't working out. If you're not getting what you need, or if your buddy wants more than you can give, have a heart-to-heart chat about what's going wrong. If it can't be fixed, it's time to move on, Dweck says.
"The purpose of a diet buddy is to enhance the weight loss journey for both partners, and make it easier and more fun for each of you," he says. If that's not happening, there's no point in sticking it out.
At the same time, if your diet buddy partnership begins to blossom into a beautiful friendship -- experts say, "Go for it!"
Says Dweck, "You may find that you are building a lifelong friendship that continues on with mutual support for the rest of your lives."