Is weight loss contagious? According to a new study published in the journal Obesity, it is.

Researchers at the Miriam Hospital Weight Control and Diabetes Research Center and the Warren Alpert Medical School at Brown University found people who are in a team-based weight loss competition influence each others weight loss to a large degree.

“We know that obesity can be socially contagious, but now we know that social networks play a significant role in weight loss as well, particularly team-based weight loss competitions,” said lead author of the study Tricia Leahey. “In our study, weight loss clearly clustered within teams, which suggests that teammates influenced each other, perhaps by providing accountability, setting expectation of weight loss, and providing encouragement and support.”

Study findings were based on a 2009 12-week statewide weight loss competition in Rhode Island. More than 3,300 overweight or obese people participated in the competition where teams of five to 11 people competed in three divisions: weight loss, physical activity and pedometer steps.

Weight loss outcomes were determined by which team an individual was on. Participants who lost significant amounts of weight — at least 5 percent of their initial body weight — tended to be on the same teams. Being on a team with more teammates in the weight loss division was also associated with a greater weight loss.

People who reported higher levels of teammate social influence increased their odds of achieving a clinically significant weight loss by 20 percent.

“Being surrounded by others with similar health goals all working to achieve the same thing may have really helped people with their weight loss efforts,” Leahey said.

Obesity is the second leading preventable cause of death in the United States. Obesity can lead to a host of serious health problems such as diabetes, heart disease and certain types of cancer. According to the Centers for Disease Control and Prevention, about one-third of American adults suffer from obesity.