NEW YORK (Reuters Life!) - That friend who stays thin despite eating anything and everything is not just annoying. He or she might also wreck your diet, according to new research.
Researchers from the University of British Columbia in Kelowna, Canada, found that when college students watched a movie and ate snacks with a companion, the students typically followed a thin friend's lead when she overindulged.
However study participants used more self-control when snacking with a heavier companion who overate.
The findings, published in the Journal of Consumer Research, suggest that seeing a thin friend devour a big meal gives us implicit permission to do the same.
"We think 'if she can eat like that and stay thin, so can I,' or 'she is having cake, then I can too,'" researcher Brent McFerran told Reuters Health.
"In other words the most dangerous person to eat with is not someone who is obese, but a thin friend with a large appetite."
For the study, McFerran and his colleagues recruited 210 female college students for what the participants believed was a study on movie viewing. Each woman watched a movie with a companion, who was actually a member of the research team.
In some cases, the researcher showed up as her normal 105-pound self, while in others she donned padding that made her appear to be obese.
During the movie, the pairs were offered snacks, with the undercover researcher taking her portion first.
In general, McFerran's team found, the students ate more when their thin companion took a large portion, versus cases where the "obese" companion took a similarly large portion.
For example, when the skinny researcher ate a lot (30 candies), the participants ate an average of 10 candies. When the researcher was "obese" and ate a lot, they ate about 6 candies.
"Eating involves much social pressure," McFerran said.
But the current findings do not mean that we need to cancel all future dinner plans with our overindulgent skinny friends.
"If we think about what we are doing in advance we are less likely to overconsume," said McFerran.
Reporting by Amy Norton from Reuters Health, Editing by Belinda Goldsmith