The findings published in Appetite said that participants ate healthy food more when others in the same age group ate more, compared with when others ate less or did not eat at all.
This effect was stronger when the other person was underweight than when she was overweight, said Mariëlle Stel, who led the study.
Though previous studies had shown that people’s eating behaviours could be influenced by the behaviours of others, most had focused on unhealthy foods. “Because influence effects of healthy food appear to be under researched and the overall effect of [a previous study] was rather small, a first aim of the present study was to replicate these findings,” said the team.
The study also sought to investigate the influence of another person’s appearance on the effects of eating healthy food as such findings were unclear.
Effect of others
The team conducted two studies. In the first, the food intake of the confederate was either 3 or 10 cucumber slices and in the second, the food intake was either 0 or 4 cucumber slices.
“In two studies, we showed that the healthy food intake of a confederate affected the healthy food consumption of participants. Specifically, we found that participants ate more cucumber slices when the confederate also ate more cucumber slices compared with when the confederate ate no or less cucumber slices.
“Furthermore, study 2 showed that this effect was stronger when the other person is underweight than when the other person is overweight,” said Stel.
Since the effect was stronger in the underweight condition, the study suggested that participants corrected their automatic food intake to some extent when observing an overweight person eat healthy food.
“It is possible that people regard an overweight person to be less knowledgeable about either the appropriate or the best eating behaviour in that situation,” added Stel.
Another (post-hoc) explanation was that perhaps underweight people reminded the participants more strongly about their diet than overweight models, which resulted in a stronger urge for healthy eating.
The team concluded that although the study was set up in an environment as naturalistic as possible in a controlled experimental situation, the situation was not representative of daily life situations. “For future research, it might be interesting to investigate food consumption in more real life settings, like during a party,” it said.
The studies
Female students from Tilburg University participated in both studies. While 144 students took part in the first study, 120 students participated in the second.
Source: Appetite
Vol: Volume 90, 1 July 2015, Pages 240–247, doi: 10.1016/j.appet.2015.03.016
‘Healthy food consumption in young women. The influence of others' eating behavior and body weight appearance’
Authors: Mariëlle Stel, et al