The weight of the people at your dinner table or even in the same restaurant can influence how much you eat, researchers have found.
They say we serve and eat more unhealthy foods and less healthy foods when eating with an overweight friend.
They say the overweight person can 'lead you astray'.
'This finding emphasizes the importance of pre-committing to meal choices before entering the restaurant,' says lead author Mitsuru Shimizu, Assistant Professor of Psychology at Southern Illinois University, Edwardsville.
He says the key is to choose what you want to eat before arriving.
'If you go into the restaurant knowing what you will order you're less likely to be negatively influenced by all of the things that nudge you to eat more.'
Researchers recruited 82 undergraduate college students to eat a spaghetti and salad lunch.
They also enlisted an actress to wear a prosthesis that added 50 pounds to her normally average weight.
WHAT YOU SHOULD DO
Brian Wansink, one of the researchers, recommends:
'Look up the menu beforehand and select a meal that suits your dietary goals.
'Or, if you're going to a buffet, pre-commit to selecting modest portions of healthy foods and with that goal in mind, those around you will have less of a negative influence over what you eat.'
Each of the 82 participants was randomly assigned to one of four scenarios: the actress served herself healthfully (more salad and less pasta) while wearing the prosthesis, she served herself the same healthy meal without the prosthesis, she served herself less healthfully (more pasta and less salad) while wearing the prosthesis, or she served herself the same less healthy meal without the prosthesis.
Participants in each scenario viewed the actress serving herself and then served themselves pasta and salad.
Researchers found that when the actress wore the prosthesis, and appeared overweight, the other participants served and ate 31.6% more pasta regardless of whether she served herself mostly pasta or mostly salad.
When she wore the prosthesis and served herself more salad, the other participants actually served and ate 43.5% less salad.
'The results demonstrated that regardless of how the confederate served, participants served and ate a larger amount of pasta when she was wearing the prosthesis than when she was not.
'In addition, when the confederate served herself healthily, participants served and ate a smaller amount of salad when she was wearing the prosthesis than when she was not. '
The team say that people simply ignore their own health goals when eating with an overweight person.
'Consistent with the 'lower health commitment' hypothesis, these results demonstrated that people may eat larger portions of unhealthy food and smaller portions of healthy food when eating with an overweight person, probably because the health commitment goal is less activated.
'More generally, this study provides evidence that the body type of an eating companion, as well as whether she serves herself healthily or unhealthily, influences the quantity of food intake. '
HOW THEY DID IT
The researchers recruited 82 undergraduate college students to eat a spaghetti and salad lunch.
They also enlisted an actress to wear a prosthesis that added 50 pounds to her normally average weight.
Each of the 82 participants was randomly assigned to one of four scenarios: the actress served herself healthfully (more salad and less pasta) while wearing the prosthesis, she served herself the same healthy meal without the prosthesis, she served herself less healthfully (more pasta and less salad) while wearing the prosthesis, or she served herself the same less healthy meal without the prosthesis.
Participants in each scenario viewed the actress serving herself and then served themselves pasta and salad.
