CHAMPAIGN, Ill. — Researchers have discovered a subtle new difference between men and women – this one occurring in the realm of eating.

In the new study of observed eating behavior in a social setting, young men and women who perceived their bodies as being less than “ideal” ate differing amounts of food after they were shown images of “ideal-bodied” people of their own gender.

Lead researcher Kristen Harrison found that “in the presence of same-gender peers, certain women eat less and certain men eat more following exposure to ideal-body images – ‘certain’ in this case referring to women and men who have discrepancies between their actual body and the kind of body they think their peers idealize,” Harrison said.

“In a nutshell,” Harrison said, “we found that, following exposure to ideal-body images, men who are insecure about their bodies eat more in front of other men, while women who are insecure about their bodies eat less in front of other women.”

Harrison is a professor of speech communication at the University of Illinois at Urbana-Champaign. The co-authors of the study are Laramie D. Taylor, a professor of communication at the University of California at Davis, and Amy Lee Marske, a teacher at Libertyville High School in Libertyville, Ill.

The study findings appear in the December issue of Communication Research in an article titled, “Women’s and Men’s Eating Behavior Following Exposure to Ideal-Body Images and Text.”

Harrison, who has focused her scholarly research on issues of nutrition and eating, perceptions of ideal-body weight and the impact of media on them, randomly assigned the male and female subjects to be tested in same-gender groups of three to nine people.

The subjects participated in one of four scenarios: Some were randomly chosen to view slides of images of fit men and women that had no accompanying text, some viewed slides that contained diet- and exercise-related text, some viewed slides that contained irrelevant text, and the control groups did not view any slides.

The participants who were to view slides were first asked to fill out a short questionnaire measuring various demographic variables and “ought discrepancies” – that is, discrepancies between their actual body type and the body type they thought their same-sex peers expected them to have; then they viewed one of the three PowerPoint presentations.

Following the presentations, they went to a second classroom where they completed a follow-up questionnaire. It was in the second classroom where food – in the form of pretzels – was present and where the participants’ consumption was unobtrusively measured.

The 30 images for the female groups were drawn from fashion, lifestyle and fitness magazines such as Cosmopolitan, Glamour, Vogue, Shape and Elle. The images for the male groups were from magazines such as Men’s Health, Men’s Fitness and Muscle & Fitness.

For the experiment, 222 women and 151 men, who were average in body weight, were recruited from introductory communication courses at two large Midwestern universities. The study took place over 16 weekdays, with 45-minute afternoon group sessions at 4:30, 5:15, 6 and 6:45 p.m. – times when college students “are typically starting to feel hungry for their evening meal, but are unlikely to have already eaten,” the researchers wrote.

The students were told that they would be evaluating the appeal of rough page layouts for a magazine under development.

The researchers found that exposure to ideal-body images with no text or paired with body-relevant text led women with body-related discrepancies to eat, on average, one less pretzel than other women, and men with body-related discrepancies to eat, on average, three more pretzels than other men.

How do these findings translate to everyday eating patterns, and what are the long-term consequences?

“It is difficult to overstate the importance of everyday, moment-to-moment decisions in shaping the quality of a life,” Harrison said.

She said that abstinence from just a few pretzels a day – amounting to about 100 calories – can result in the loss of more than a pound of fat during the course of a year, and the addition of a few pretzels a day can do the opposite, which she conceded, doesn’t sound that significant. However, if people are viewing “ideal-body media” regularly, their body-weight and health could be significantly affected, she said.

For example, “If a woman is a regular user of ideal-body media such as fitness and fashion magazines, not to mention television programming featuring advertisements for diet foods and products, she may be moved to abstain from eating several times a day – even when she is hungry – resulting in significant weight loss over time.”

Harrison noted that people thinking about the national obesity epidemic might respond to such abstinence with, “Good! This is what should happen.”

“But the fact that this happens even to skinny women means that such weight loss could be unhealthy,” Harrison said.

“Similarly, a man who is vulnerable to ideal-male images due to the presence of an actual body vs. ideal body self-discrepancy may be moved to eat even when he is not hungry, just to reassure himself and other men that he is sufficiently masculine.”

The findings of the current study also show that this effect occurs regardless of body mass.

“Eating in response to external cues rather than internal hunger signals is one of the first steps involved in the development of disordered eating, be it anorexia, bulimia or compulsive eating. Our commercial mass media are filled with such external cues.

“It is our hope that future studies will be devoted to furthering our understanding of how young people, especially those who are most vulnerable, can resist the pull of those cues.”