Is obesity a socially transmitted disease? In order to try to find out, researchers in the United Kingdom conducted a systematic review of several experimental studies, each of which examined whether or not providing information about other peoples' eating habits influences food intake or choices. Their results are published in the Journal of the Academy of Nutrition and Dietetics.
The review looked at a total of fifteen studies from eleven publications. Eight of the studies examined how information about food intake norms influenced food consumed by participants. Seven other studies reported the effects of food choice norms on how people decide what food to eat. After examining the data, investigators found consistent evidence that social norms influence food.
This meta-analysis found that if participants were given information indicating that others were making low-calorie or high-calorie food choices, it significantly increased the likelihood that participants made similar choices. Also, data indicate that social norms influence the quantity of food eaten. Additionally, the review indicated that suggesting that others eat large portions increased food intake by the participants. There was also a strong association between eating and social identity.
"It appears that in some contexts, conforming to informational eating norms may be a way of reinforcing identity to a social group, which is in line with social identity theory," explains lead investigator Eric Robinson, PhD, of the University of Liverpool. "By this social identity account, if a person's sense of self is strongly guided by their identity as a member of their local community and that community is perceived to eat healthily, then that person would be hypothesized to eat healthily in order to maintain a consistent sense of social identity."
The need to solidify our place in our social group is just one way investigators found social norms influence our food choices. The analysis also revealed that the social mechanisms that influence what we decide to consume are present even when we eat alone or are at work, whether or not we are aware of it.
"Norms influence behavior by altering the extent to which an individual perceives the behavior in question to be beneficial to them. Human behavior can be guided by a perceived group norm, even when people have little or no motivation to please other people," says Dr. Robinson. "Given that in some studies the participants did not believe that their behavior was influenced by the informational eating norms, it seems that participants may not have been consciously considering the norm information when making food choices."
Investigators caution that more research is needed, but that these types of studies can help us understand the way people make decisions about food consumption and can help shape public policy and messaging about healthy choices.
"The evidence reviewed here is consistent with the idea that eating behaviors can be transmitted socially," remarks Dr. Robinson. "Taking these points into consideration, the findings of the present review may have implications for the development of more effective public health campaigns to promote 'healthy eating.' Policies or messages that normalize healthy eating habits or reduce the prevalence of beliefs that lots of people eat unhealthily may have beneficial effects on public health."
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"What Everyone Else is Eating: A Systematic Review and Meta-Analysis of the Effect of Informational Eating Norms on Eating Behavior," by Eric Robinson, PhD; Jason Thomas; Paul Aveyard, PhD; Suzanne Higgs, PhD, Journal of the Academy of Nutrition and Dietetics, DOI: 10.1016/j.jand.2013.11.009