If you’re having trouble losing weight, maybe you just need a buddy.

A new study finds people who pair up while dieting have better results than those who go it alone.

The Weight Control and Diabetes Research Center at the Miriam Hospital in Rhode Island discovered that when people were assigned to a “health coach,” they lost an average of nine percent of their body weight over 24 weeks.

Not only is that an unusually high success rate, the “health coach” doesn’t have to be a behavior specialist — it can just be a friend. Either way, the person provides someone to whom the dieter must be accountable, and that seems to be why the system works.

In the study, participants met with their coaches weekly or emailed a progress report with details about their weight, food intake and exercise, with the coach later providing feedback.

The researchers say coaches provide motivation and support, and they can also point out potential pitfalls you’re overlooking. For example, if she sees that you do most of your eating at night, she could help you with a strategy to eat better during the day so you aren’t so hungry when the sun goes down.

Tricia Leahey, who led the research, said, “Our study suggests health coaches may not only yield impressive weight loss outcomes, but that ["peer"] health coaching may be particularly promising as a cost-effective obesity treatment strategy.”

[Time]