Last Night's Viewing: My Daughter the Teenage Nudist, Channel 4

The perfect body is one you're happy with, said Daryl in My Daughter the Teenage Nudist. Daryl is a cheerful proselytiser for the virtues of naturism or rather (since that term doesn't seem to market well with a younger demographic) "nakidity", a word that I sincerely hope will remain a Daryl exclusive. And, as nudists tend to, he was prone to make the case that nobody should be ashamed of what nature had given them. "We are all just human beings at the end of the day," he said, staring the camera straight in the eyes. This would have been a slightly more persuasive argument if Daryl hadn't been on his hands and knees at the time, with a beautician busy down the back end ripping hairs from his crack. Is he not happy with his God-given buttock hair? And if so, doesn't that slightly undermine his argument?

Daryl doesn't have a daughter, by the way, or at least not one who was on show here. In fact, there didn't seem a lot of justification for that title at all, beyond its obvious appeal to a certain kind of prurience. Two mothers did appear from time to time, looking a bit anxious about their daughters' experimentation with nudity, but Amanda Blue's film was less about their worries than the fact that old naturists aren't being replaced by young naturists at a pace that will keep up the numbers. Membership – if you'll forgive the term – is down at British Naturisim and while there are still plenty of young people who like to get their bits out, they don't seem very keen to formalise their enthusiasm, or to play handball in the nude.

Mollie, one of the daughters, rather unpersuasively suggested that her interest had come about almost by accident: "I Googled 'naked bike ride' for some reason and I was like, 'Oh my God! I have to go to this!'" she said, explaining how she'd ended up cycling through London with her top off, in a somewhat quixotic protest against global warming. Her friend Clare was going to come too, but her mum found out about it first and stopped her and Clare remains wary about the attractions of letting it all hang out: "Do I really want to see that part of Luke in my life?" she asked Mollie scathingly about a mutual friend. Bad luck, Luke, if you were hoping the answer was "yes". Then they all went off to a clothes-optional event at a country house, where they skinny-dipped in a pond while a group of old men with the complexions of leather suitcases peered curiously at them through the shrubbery.

Up in Manchester, Alex and her friends were going nude to "challenge the domination of perfect body images", though it has to be said that Alex's body, in particular, didn't offer much of a challenge. It was a point not lost on an indignant woman who encountered Alex and a friend topless on the street, trying to drum up interest in a naked art event. "You've put two more-or-less beautiful people out there," she said indignantly to Alex's friend Russell, before rather tactlessly suggesting that he might counter body-fascism more effectively himself. Even more double-edged was the remark of a young woman at a naked tea party arranged by the naked vegan cooking group, as she explained how her initial startle-response to male penises had been soothed by familiarity: "When I saw yours," she said to the party's host, "I thought, 'Oh Jess's is a lot less intimidating'." To his credit, Jess wasn't entirely unmanned by this remark, and insisted that his own problems with body image (he'd had eating issues in the past) had been helped by public exposure. They were eating ginger nuts as it happened. The camera glimpsed at this tempting double-entendre longingly, but then moved on without biting.