Sales clerks tend to discriminate against shoppers who are obese, according to new study findings.

Investigators found that when women wore a prosthetic suit designed to make them look obese, they were treated more rudely, and received fewer smiles and less eye contact from sales clerks at a Houston, Texas, shopping mall than when they shopped without the fat suit.

Sales clerks - almost three-quarters of whom were women - also tended to end interactions with obese shoppers more quickly, and use a negative tone with them.

Obese shoppers tended to experience more discrimination when they were casually dressed than when they were in professional attire.

However, when the apparently overweight shoppers sipped a diet soda and said they were trying to lose weight, they were treated just as nicely as when they shopped without their artificial bulk.

Weight-related discrimination is something that is “pervasive in all kinds of social interactions,” even when clerks are paid to be nice to customers, study author Eden King at Rice University in Houston told Reuters Health.

A survey of shoppers also showed that people who were obese said they experienced more discrimination from sales clerks, which caused them to spend less time in a store and less money while there. This shows that storeowners have a financial, as well as ethical, incentive for addressing discrimination among their staff, King said.

“We’re hoping that people will pay attention and become more aware” of what obese people go through every day, said King, who started the study as an undergraduate student.

During the experiments, King and her team asked ten white women of average weight between the ages of 19 and 28 to visit a number of stores in a shopping mall. Women wore casual or professional clothes, or a prosthetic suit that made them a size 22.

In all instances, women followed a script, and clearly told clerks they were looking for a gift for someone else.

After each visit to 152 stores, the women completed questionnaires about how they had been treated, and the researchers reviewed recordings of the interactions from a device hidden in shoppers’ bags.

In a separate experiment conducted in 66 stores, the investigators asked seven women to shop with and without the fat suit, and to either drink a diet soda and say they were trying to lose weight, or drink an ice cream drink and say they were not on a diet.

King and her team also interviewed 191 obese and non-obese white shoppers about their experiences while shopping.

They will report their findings in detail during the upcoming annual conference of the Society for Industrial and Organizational Psychology, April 15-17 in Los Angeles, California.