Study co-authors Kevin M. Kniffin, a postdoctoral researcher at Cornell University's Dyson School of Applied Economics, and Brian Wansink, the director of Cornell's Food and Brand Lab, measured the amount of jealousy reported by current romantic partners if one of them were contacted by an ex-lover and subsequently engaged in several food- and drink-based activities.
"Our research suggests that sharing lunch involves more than the physical consumption of calories," Kniffin said in a statement. "We consistently found that meals elicit more jealousy than face-to-face interactions that do not involve eating -- such as having coffee. These results are consistent for both men and women."
For couples attuned to relationship risks, the study suggested men and women who "do lunch" run the risk of a jealous spouse or partner at home, Kniffin said
"It's key to remember that from your spouse's perspective, it's not "just lunch," Wansink said. "While meals can strengthen social relationships, they can also destroy them."
The findings were published in the journal PLoS ONE.