Weight loss is contagious

The study by the Miriam Hospital's Weight Control and Diabetes Research Centre and The Warren Alpert Medical School of Brown University found that participants in a team-based weight-loss competition not only lost a similar amount of weight as their comrades, but those who said their teammates played a large role in their weight loss shed the most fat.

"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 Dr Tricia Leahey.

"In our study, weight loss clearly clustered within teams, which suggests that teammates influenced each other, perhaps by providing accountability, setting expectations of weight loss, and providing encouragement and support."

The findings were based on the 2009 Shape Up Rhode Island (SURI) campaign, a 12-week online weight loss competition were teams competed against other teams in three divisions: weight loss, physical activity and pedometer steps.

Weight loss outcomes were clearly determined by which team an individual was on. Participants who lost more than least 5 percent of their body weight tended to be on the same teams, and being on a team with more teammates in the weight-loss division was also associated with a greater loss. Participants who reported higher levels of teammate support increased their odds of achieving a clinically significant weight loss by 20 percent.

"This is the first study to show that in these team-based campaigns, who's on your team really matters," she said.

"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."

The study was published in the journal Obesity.

Want to see team weight loss in action? Watch Excess Baggage weeknights 6.30pm on GO! and catch-up with full episodes on Catch-up TV.