Dining with a friend could be bad for those on a diet - it tempts you into eating unhealthy dishes from the menu, just to keep him or her in good humour, says a study.
Researchers led by Eric Robinson, psychologist at the University of Birmingham, believe it may help to explain why groups of friends often put on weight at the same time and why some women complain that they get heavier when they find a boyfriend - they start to copy his eating habits.
"There is a lot of evidence that points towards this idea that your friends make you fat. If you have got friends or people you know who have put on weight recently, then you will put on weight too," said Robinson.
"We found that pairing people with unhealthy eating partners reduced the amount of healthy food they were eating. They tended to pick the foods that were high in calories," added Robinson, the British Journal of Nutrition reported.
"Recognising that this effect is real could help people who are trying to watch what they eat. They could even look at a menu and try to decide what they are eating before those they are with to help avoid being influenced," the Telegraph quoting Robinson, said.
The research asked 100 female volunteers to select from a choice of food consisting of healthy fruit and vegetables or unhealthy foods including crisps, pastries and cocktail sausages.
They found that when they were eating with someone who had been asked to pick unhealthy options, the volunteers also picked far more of these compared to when they ate alone or with someone who chose healthier foods.
Suzanne Higgs, reader in the psychobiology of appetite and study co-author, added: "This research underlines the social nature of eating and how this influences our behaviour."