People eat more with friends and family than when dining alone - a possible throwback to our early ancestors' approach to survival, according to a new study.
Previous studies found that those eating with others ate up to 48 per cent more food than solo diners and women with obesity eating socially consumed up to 29 per cent more than when eating alone. This phenomenon is known as 'social facilitation'.
Experts at the Universities of Bristol, Birmingham and New South Wales found that eating 'socially' has a powerful effect on increasing food intake relative to dining alone, after evaluating 42 existing studies of research into social dining.
They explain that ancient hunter gatherers shared food because it protected against periods of food insecurity – this survival mechanism may still persist today, leading to people eating more with friends and family because:
- Eating with others is more enjoyable and enhanced reward from social eating could increase consumption.
- Social norms might 'permit' overeating in company but sanction it when eating alone.
- Providing food becomes associated with praise and recognition from friends and family, strengthening social bonds.
Professor Jeff Brunstrom, an expert in behaviour nutrition in the University of Bristol's School of Psychological Sciences, said: "Humans are natural food sharers, perhaps more so than any other species. But equitable sharing also requires monitoring, and if someone else eats a large amount then it's important to match them to get the same benefit.
"In our ancient past this strategy would have been optimal for social cohesion and personal health. In fact, we think it was so important that it became 'hard wired'. Our findings are exciting because they suggest modern humans are no different and that the same food-sharing strategy continues to influence our dietary choices and habits, even today."
"This discovery is exciting because it suggests that our dietary choices and habits continue to be influenced by 'hard wired' strategies that previously benefited hunter gatherers."
The study highlights that, as with many other species, humans tend to share a common food resource. Most humans are no longer hunter-gatherers, but mechanisms similar to those that once served efficient foraging continue to guide our dietary behaviour.
Recent and rapid transition to a dietary landscape in which food is abundant has created forms of 'evolutionary mismatch' - inherited foraging strategies no longer serve their former purpose.
Researchers note that, in the case of social facilitation, we have inherited a mechanism that once ensured equitable food distribution, but now exerts a powerful influence on unhealthy dietary intakes.
The same process has been observed in chickens, rats, gerbils and other species, suggesting it serves an ultimate purpose. Individuals compete for resource and research suggests that eating more than others is likely to lead to ostracism, which, in turn, reduces food security.
This creates a tension between an individual 'being seen' to share food altruistically and eat as much as they need.
Research leader Dr Helen Ruddock, from the School of Psychology at the University of Birmingham, said: "We found strong evidence that people eat more food when dining with friends and family than when alone. However, this social facilitation effect on eating was not observed across studies which had looked at food intake amongst people who were not well acquainted.
"People want to convey positive impressions to strangers. Selecting small portions may provide a means of doing so and this may be why the social facilitation of eating is less pronounced amongst groups of strangers.
"Findings from previous research suggest that we often choose what (and how much) to eat based on the type of impression that we want to convey about ourselves. Evidence suggests that this may be particularly pronounced for women eating with men they wish to impress and for people with obesity who wish to avoid being judged for overeating."
Paper
'A systematic review and meta-analysis of the social facilitation of eating' by H. Ruddock at al in The American Journal of Clinical Nutrition
