BIRMINGHAM, ENGLAND— Social media may play an important role in shaping consumers’ eating behaviors.

A new study from Aston University, Birmingham, England, found that participants ate an extra fifth of a portion of fruits and vegetables for every portion they thought their social media peers ate. If they believed their friends got their “five a day,” they were likely to eat an extra portion themselves.

Conversely, Facebook users were found to consume an extra portion of unhealthy snack foods and sugary drinks for every three portions they believed their online social circles did. The finding suggests consumers eat around a third more indulgent foods if they think their friends also indulge, according to researchers.

The study, published in the scientific journal Appetite, provides the first evidence that suggests online social circles may implicitly influence eating habits. Those who felt their social circles approved of eating indulgent food ate significantly more themselves, while those who believed their friends ate a healthy diet ate more portions of fruits and vegetables. These perceptions may be formed by seeing friends’ posts about the food and drink they consumed, or from a general impression of their overall health.

“This study suggests we may be influenced by our social peers more than we realize when choosing certain foods,” said Lily Hawkins, a Ph.D. student who co-led the study. “We seem to be subconsciously accounting for how others behave when making our own food choices. The implication is that we can use social media as a tool to ‘nudge’ each other’s eating behavior within friendship groups, and potentially use this knowledge as a tool for public health interventions.”

While social media was found to influence diet, researchers found no link between participants’ eating habits and their body mass index (B.M.I.), a standard measure of healthy weight. Future research will focus on tracking participants over time to see whether the influence of social media on eating habits has a longer-term impact on health and weight gain.