Why Do We Eat Less When We Eat Alone? ⋆

Why Do We Eat Less When We Eat Alone?

In a study conducted by the University of Birmingham, it appears that there is an evolutionary reason why people tend to eat more when they are with friends than when they eat alone.


The research, published on October 4th 2019, in the The American Journal of Clinical Nutrition looked at 42 other studies on the subject of food consumption and the influence of social factors.

In a study by the British Psychological Society, it was found that if someone ate with friends their meals would be around 29-48% larger.  In other studies, it was found that calorie consumption also increased by 23% compared to the calorie intake when someone ate alone.

This is known as the ‘social facilitation’ effect and there were other influences on consumption too.  For example, if someone knew they could be seen by strangers they would often choose smaller portions to avoid negative perceptions.

Sharing Our Food Sources

On the other hand, once people are with those they know well they have a tendency to eat a lot more and it is suggested that this may be a throwback to when our ancestors were living in hunter-gatherer communities.  Prehistoric humans were likely, like their modern counterparts, to share their food source.


However, it would seem that the survival strategy that worked so well for our ancestors is now working against us.  In what is called an ‘evolutionary mismatch’ these same strategies are now leading to excess food intake.

Other factors that influence how much food we consume includes our gender and also how much we weigh.  For example, a woman is likely to eat less food if she is eating with men and this is unchanged by her relationship with them. The supposition is that this could be because she wishes to impress the men in the group.  It is also noted that people who carry excess weight will eat up to 18% less in the company of others than when they are alone, perhaps because they want to avoid negative judgments about their eating habits.