Dr. Gupta is a licensed psychologist and professor at Barnard College, Columbia University. She specializes in the treatment of anxiety and eating/weight issues at 
How much food your friends eat influences your own eating
July 10, 2012
Sitting at a restaurant with friends, you’re trying to decide whether or not to finish your entrée and possibly order more food. How would your decision be different if you were alone, with strangers, or with different friends? A new research study suggests that if your friends eat less food, you’re also likely to eat less and continue eating less when you're alone soon thereafter.
The study, to be published to the journal Appetite, was conducted by researchers at the University of Minnesota. They designed a laboratory experiment in which small groups of college friends were served fresh chocolate chip cookies while being asked to discuss a campus issue; then the friends took their plates of cookies into separate rooms to complete another task individually. For about half the groups, the researchers secretly asked 2 of 3 friends to avoid eating any cookies in front of the third friend (who wasn’t told anything). For everyone else, the researchers secretly asked 2 of 3 friends to eat only 2 cookies as a group before leaving for individual tasks.
The researchers found that students ate fewer cookies as a group when their friends ate no cookies compared to when their friends ate a couple cookies. Even when the friends split up, people continued to eat fewer cookies alone if they had just watched their friends avoid eating the cookies.
The study demonstrates the potentially powerful influence of friends and social norms over eating behaviors. It would have been interesting to see if people also ate much more food if their friends were asked to, say, eat all the cookies that were served to them.
In addition, the time between eating with friends and eating alone was just a few minutes in this study. What happens if several hours pass? Perhaps having dinner with friends who eat fewer sweets could reduce solo binge eating later at night. Or maybe this would actually increase the urge to binge eat later at night? Hopefully other studies examine how social norms among friends relate to eating in bulimia and binge eating disorder.
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Dr. Gupta is a professor at Barnard College of Columbia University and provides invidual therapy at Tribeca Psychology
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