Channel Four, which will air the show, said no intercourse or nudity will be seen in the Sex Box programme but the “immediacy” will encourage a more open and honest discussion about their experiences.
The hour-long show, to be screened in the UK next month, is part of the broadcaster’s Campaign For Real Sex season, which will look at the effect of pornography on the love lives of ordinary people around the UK.
The three couples taking part in Sex Box are an engaged couple who have rekindled their romance after being childhood sweethearts, a duo in their 20s and a gay couple in their 30s.
The panel of experts who will discuss the sex sessions include psychotherapist Phillip Hodson, relationship expert Tracey Cox and sex columnist Dan Savage.
“The sex we see on screen, in magazines and increasingly online bears little relation to the real experiences of real people,” said Ms Frostrup, who is also a newspaper agony aunt.
“I’m delighted to take part in this attempt to have a frank conversation about an essential element of all our lives.”
Sex Box, to be shown on October 7, is inspired by work undertaken by sex researchers in which couples discuss their activities straight after sex.
The season will also include a documentary examining the effect on teenagers of being bombarded by sexual imagery and another program in which porn fans get to date the stars of sex films in order to understand the reality of their lives.
“It is a rather mischievous, fun idea that actually allows sex to be completely private but the conversation to be truthful and immediate,” said David Glover, a commissioning editor for Sex Box.