A waiter carries pizza at a restaurant in Rome Reuters/Dario Pignatelli

The weight of the waiter affects what a diner may order. Aside from the usual techniques restaurants employ to persuade customers to eat and order more, the findings show that a person’s weight may also be used to aid in the restaurant’s success.

The study was conducted by researchers from the Cornell Food and Brand Lab, a non-profit research facility at Cornell University. The research team studied 497 diners in 60 restaurants and observed that those diners who ordered their dinner from heavier restaurant servers were four times more likely to order dessert and 17 percent more alcohol.

Tim Doering, a researcher at the Cornell Food and Brand Lab, remarked that no one goes to a restaurant to begin a diet. Because of this, people are very susceptible to cues that give them the permission to order and eat anything. Doering noted that a fun, happy and heavy wait staff might lead a diner to think that it is alright to cut loose a little and enjoy whatever the restaurant offers.

The study, published in the current issue of the journal Environment and Behavior, involved analysing the data gathered from the diners eating in casual American restaurants such as Applebee's and TGI-Friday's. The research team compared the diners’ orders to the body mass index or the height and weight ratio of the person who served them and the size of the diner. Curiously, a heavier waiter or waitress seemed to have an even bigger influence on the skinnier diners, Doering added.

Aside from the size of the wait staff, the lighting, music and even where people sit have been shown to impact and unknowingly bias what customers order. Co-author Brian Wansink, the director of the Cornell Food and Brand Lab and author of Slim by Design, advised that deciding whether ordering either an appetiser or a dessert before going out to eat could be one of the best “diet defences.” Following this personal ordering rule-of-thumb will help people manage their health when changing the music or the waiter in a restaurant is not allowed.