"For some people, the anonymity of having an Internet buddy is the best solution. For others, it has to be someone who they can get together with for a Wednesday night weigh-in," says Shafran. "It doesn't matter, as long as both buddies want the same thing."
No matter what your mode of communication, it's important that buddies spend time listening to each other.
"It can be online in a chat; it can be on the phone; it can be in an email; or it can be in person, as long as there is some time that each of you can devote to listening and encouraging the other," says Dweck.
It's also important to recognize that encouragement comes in many different forms.
"For some people, it means hearing kind and supportive words; for others, it means having someone come by and literally drag them out of the house and to the gym," Dweck says. "As long as both buddies know what the other needs and expects, then they can be there for each other."
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.