Vegetarians are bigger love cheats than meat-eaters, according a new survey.
Just over four out of ten veggies (42%) have admitted being unfaithful to a partner in the past, compared to 31% of carnivores.
Veggies sleep with new partners more quickly than meat-eaters, too.
They have sex the first time after an average of 2.7 dates, compared to 3.3 dates for meat-eaters.
Two-thirds of vegetarians (67%) said they would sleep with a meat-eater if they were attracted to them, despite being uncomfortable about their food choices.
One in six vegans (15%) would have sex with a meat-eater.
Carnivores are much more relaxed about the eating habits of their lovers.
The vast majority of meat-eaters (96%) said they would not be put off a lover if they were vegetarian and 92% were happy to date a vegan.
The results come from a new survey from IllicitEncounters.com, the UK's biggest dating website for married people.
It polled 2,000 people (1,000 meat-eaters and 1,000 vegetarians and vegans) to find their dating preferences.
Almost all vegetarians and vegans (92%) said they would be happier dating someone who didn't eat meat.
In contrast, only 32% of meat-eaters expressly preferred a potential partner to be a carnivore, too.
The poll also looked at the most attractive vegetarians with Oscar winner Natalie Portman winning the female poll and Hollywood star Tobey Maguire winning the male vote.
Some 3.5 million people in the UK are vegetarians - around 7% of the population.
IllicitEncounters.com spokesman Christian Grant said: "If you want to have an affair, date a veggie.
"They are more likely to have cheated in the past and tend to initiate sex more quickly than meat-eaters.
"The reason why is that vegetarians can often be better communicators and are more comfortable sharing their feelings than meat-eaters.
"They are also more likely to walk out on a relationship if it is not working."
Every week, around 20,000 people in the UK are having affairs on IllicitEncounters.com.
More than one million people have registered with the site since it started in 2003 and the highest proportion of members are wealthy people in London and the Home Counties.
The average income of male members is £54,000-a-year.
Around 10% of its members are vegetarians.
Ten most attractive female vegetarians
1 Natalie Portman
2 Miley Cyrus
3 Naomi Watts
4 Alicia Silverstone
5 Michelle Pfeiffer
6 Gwen Stefani
7 Kate Winslet
8 Ellen DeGeneres
9 Shania Twain
10 Ellie Goulding
Top ten most attractive male vegetarians
1 Tobey Maguire
2 Joaquin Phoenix
3 Christian Bale
4 Woody Harrelson
5 Russell Brand
6 Ricky Martin
7 Jared Leto
8 Chris Martin
9 Bryan Adams
10 Paul McCartney