Diners order significantly more food and drink when served by an overweight waiter or waitress, according to a recently published study.

“In a novel approach, we showed that diners can be influenced by their surroundings in general and furthermore by their social interactions in particular,” Tim Döring and Brian Wansink wrote in their study. “This study suggests that it does not take profound interactions between individuals to alter their eating behavior.”

The study was published online December 28 in the scientific journal Environment & Behavior.

A team of research assistants visited 60 restaurants, where they observed a total of 497 interactions between diners and servers. While visiting the restaurants, the research assistants recorded the estimated body characteristics of both the diners and the servers. They also recorded how much food and drink was ordered.

A statistical analysis of this data found that a server’s body mass index (BMI) — a simple measure of body fat based on height and weight — influenced how much their customers ordered and ate. The higher a server’s BMI, the more meals the diners ordered, regardless of their own body type.

Diners were four times more likely to order dessert and ordered 17.65 percent more alcoholic drinks when their server had a BMI that was over 25. A BMI greater than 25 is considered overweight by most health experts.

The relationship between the server’s BMI and their customers’ eating behavior remained significant even after accounting for ethnicity, gender, weight, height, and age.

“Diners may order and eat more food and beverages in the presence of a heavy person because a heavy person sets a social norm,” Döring and Wansink said.

Some restaurants, such as the chain Hooters, have faced lawsuits for discriminating against overweight employees. But this research suggests forcing waiters and waitresses to be slim is bad for business. “If anything, heavy wait staff might increase sales,” Döring and Wansink noted.