If you want your kids to eat their broccoli, you might try smiling when you eat your own veggies, a small study suggests.

The French research team asked 120 adults and children to look at various photos of people eating. In the kids, the effect of the photos was much more complicated than in the adults.

In general, adults paid attention to body weight. That is, they were less likely to want a given food when the photo depicted an obese person eating it, versus a normal-weight diner.

Children, on the other hand, had more complex reactions.

If the food was something they already liked -- chocolate, for example -- they wanted it, regardless of how heavy or thin the person in the photo was. But if they didn't like the food, their ratings of it declined even further if they saw a photo of an obese person (but not a thin person) consuming it.
What's more, children were influenced by emotions.

Photos of people happily eating made them want a favorite food even more - regardless of whether the eater was heavy or thin. In contrast, a photo of a person looking "disgusted" by that same food tended to turn the children off -- again, regardless of the person's weight.

If a child disliked the food, seeing a diner with a pleasant expression made the child more open to the food. But that pleasant face was more effective when the person was thin rather than obese.

The findings, published in the journal Obesity, suggest that adults' eating preferences are uniformly influenced by images of body weight.

Children, on the other hand, also factor in their own likes and dislikes, and other people's emotions.

"The children's reactions were unexpected," researcher Sylvie Rousset, of the French National Institute for Agricultural Research, told Reuters Health in an e-mail.

"To our knowledge, no experiment has shown the influence of 'disgusted' or 'pleasant' faces on children's desire to eat," she said.

Between the ages of 5 and 8 -- the age range of children in this study -- kids may be prone to imitating the emotions of people around them, Rousset explained. So seeing a pleased- or unhappy-looking diner may have a bigger impact on children than it would on adults.

Children in the study were affected by images of body weight to some extent. That, according to Rousset, suggests that children are aware of some of the negative stereotypes associated with obesity, but they are less influenced by them than adults are.

So what does all of this mean?

For one, it might be worthwhile for parents to try to look happy about eating healthy foods. (Parents, Rousset noted, often automatically express their feelings about a tasty or less-tasty food via facial expression.)

But of course, eating behavior is complex. According to Rousset, studies like the current one are aimed at uncovering the different "psychosocial" factors involved in shaping children's attitudes toward food and their longer term eating habits.

How well the findings from a study setting translate into real life is not clear -- since real life is complicated.

Adults in this study were less likely to want to eat when viewing a photo of an obese person dining. But there is also research suggesting that people eat more when dining with a friend than with a stranger -- especially when they and their friend are both overweight.