A BBC show has challenged 12 teenagers to stay celibate for five months.
The BBC said the teenagers were "a complete cross-section" of Harrow
In No Sex Please, We're Teenagers, two Christian youth workers tried to get participants to swap "casual sex for old-fashioned courting rituals".
They said the young people would be happier if they were in long-term, serious relationships.
"This is not a reality show in the Big Brother sense," a BBC spokeswoman said. "It is a three-part observational documentary series."
The teenagers, aged between 15 and 17 and from Harrow, north-west London, attended weekly "Romance Academy" sessions with the youth workers.
They also spent a weekend sharing a house with two rules - girls and boys were not allowed in each other's bedrooms and no alcohol.
The youngest participant was Wesley, 15, who lost his virginity at the age of 12. The parents of the 12 teenagers agreed to the project.
The BBC spokeswoman said the youngsters were not chosen for their promiscuity.
"Some of them haven't had sex at all - it's a complete cross-section," she said. "They're all from Harrow but they all go to different schools and they're all from different cultures and different religions."
The youths described the Romance Academy as "life-changing", she said.
No Sex Please, We're Teenagers is on BBC Two from 6 September.