It may be "just lunch" but a meal with an ex is dangerous territory for relationships, a study has shown.
A restaurant rendezvous is more likely to spark feelings of jealousy in a current partner than non-food related activities, US experts found.
Scientists say the findings underlie the fact that sharing food is more important than mere nutrition.
Students were asked to imagine how jealous they would be if their boy or girlfriend engaged with a former romantic partner in different circumstances.
They also had to imagine how their best same-sex friend would feel in the same situations.
Participants had to rate jealousy feelings on a scale of one to five, ranging from "not at all jealous" to "very jealous".
The scenarios involved email messaging, speaking on the phone, meeting for coffee, or having lunch or dinner together.
Sharing meals prompted the strongest jealous response, and emails the least.
A morning coffee was seen as less innocent than a phone conversation, but not as serious as lunch.
In their paper, published in the online journal Public Library of Science ONE, the scientists refer to a dating service called "It's Just Lunch".
They wrote: "Our studies suggest that the professional matchmaking company 'Its Just Lunch' perhaps unknowingly benefits from implicit beliefs about eating together that helps them to connect people. But moreover, our findings also suggest that a more accurate and innocuous saying might be 'Its Just Coffee', since people seem to view drinking coffee during the day as relatively more platonic."
Study leader Dr Kevin Kniffin, from Cornell University, New York, said: "By applying a functional view of jealousy, our studies yield the inference that people think meals can be more than just meals."
Five Ways To Spice Up Your Dating Life
By life coach <a href="http://www.sophiadavis.co.uk/" target="_hplink"><strong>Sophia Davis</strong></a>.
Get The Latin Fever
"Why not try a Salsa class with your date? Work together to learn new dance moves and then show them off together. There are plenty of classes available for all levels of experience."
"Go on an adventure and get energetic by solving mazes, climbing assault courses and swinging on ropes. Here, you will walk around what looks like an enchanted forest climbing trees and letting go of fears and inhibitions by throwing yourself into nets and such like. These are so much fun to experience and are dotted around the country so perfect for wherever you are based."
Have A Laugh
"If you want to laugh, try a comedy club. There are loads of them dotted around the country, and you can have a drink and watch some talented comedians in action (if you do some research). Laugh till your ribs hurt, and share fun times and light-hearted entertainment with your new dating partner."
Listen To Music
"Put the music back into your dating life by taking your diet to an outdoor music event, or an indoor concert. Rock out and listen to mellow jazz, it's your choice, but it'll definitely be a conversation starter and a chance to show off your moves!"
"Go for a romantic stroll, hand in hand in the outdoors. Visit a Christmas market or fair and get the adrenaline going by going on one of the rides, or show off your skating skills on the ice rink. Have a drink at one of the open bars, or just have a walk around and enjoy the festive buzz."