You only get one chance to make a first impression. And the shape of your body has a lot to do with the snap judgment that others make about you.

The judgments we make about peoples' personalities based on their body shape are probably universal and likely to vary by culture, ethnicity and even age. Researchers at the University of Texas at Dallas presented college students with 140 detailed, three-dimensional body models in order to look at some of the inferences that young Americans make about particular body types.

A study reinforces some of life's more unpleasant truths.

The models — 70 male and 70 female — were created using data from laser scans of actual human bodies, bodies whose precise measurements were known. The researchers showed these models to 76 college students and asked them whether 30 different personality traits applied to a particular body.

It's no secret that heavier people are sometimes seen as lazy and careless, even by their doctors.

Students participating in the study also generally judged heavier bodies as being associated with these and other negative characteristics. They took a more positive view of lighter bodies, describing images of those models as self-confident and enthusiastic.

There were several other shape-based associations. One example: classically feminine (pear-shaped) and classically masculine (broad-shouldered) bodies were seen as having active traits, such as being quarrelsome, extraverted and irritable. Male and female bodies that were more rectangular were viewed as having relatively passive character traits, such as being trustworthy, shy, dependable and warm.

The researchers found that they could reliably pick the traits people would associate with a particular body shape, with features related to extraversion and conscientiousness having the strongest consensus among these American students.

“To our knowledge, this is the first study to consider the role of more nuanced aspects of body shape — beyond height and weight — in personality judgments about people,” said the study's co-author, Alice O'Toole, a professor in the School of Behavioral and Brain Sciences at the University of Texas at Dallas.

Even though this study goes beyond previous research, it reinforces some of life's more unpleasant truths. Yes, it would be nice if people were judged on their abilities and inner selves, but the world doesn't always work like that. Round people — and there are no shortage of them these days — are often seen as lazy, incompetent and ugly. This doesn't help them at work, play or romance — three more reasons for them to get in better shape. Fair or not, people will see them in an entirely different light if they do.

The study appears in Psychological Science.