Dr Jessen Christian decided not enough was being done to prepare children for safe, responsible use of the internet and social media.
Our favourite TV doctor tells teens how to cope in a digital world, writes Guy Kelly.
On the hottest day of the year so far, Dr Christian Jessen is getting worked up. We're in the library of a hotel in central London, and the 41-year-old - immaculate but overdressed in red chinos, cardigan, pinstripe shirt and pinstripe jacket - is enjoying a good rant. The target of his ire? Instagram.
"It's all to do with comparing your life with other people's," he says. "Photos, photos, photos of everything, usually heavily doctored. We all know how it works, but we're still fooled by it, and young people grow up feeling inadequate because they can never switch this stuff off. When I was growing up, you could turn the telly off and walk away."
In fairness, Jessen has good reason to steer clear of the photo-sharing service. Despite spending much of his adult life attempting to solve other people's medical problems - through his training at UCL, working in Africa, his current Harley St clinic and countless television programmes - last year he revealed his own struggle with body dysmorphia.
Growing up in London and attending prestigious boarding school Uppingham, Jessen was plagued by anxiety about being too skinny, causing him to work out obsessively. He has not "fully conquered" the disorder and, as a result, stays off Instagram.
"I don't like this idea of posting pictures and comparing. I'm particularly susceptible to that and I know it would be a triggering thing for me," he explains. "I stay away from it, knowing it's not the best thing for me at all."
It has been more than a decade since Jessen arrived on our screens to prod and poke patients on Embarrassing Bodies, which ran for eight series. Other successful programmes, such as Supersize vs Superskinny, and countless documentaries have established him as the UK's favourite TV doctor.
Jessen is chiselled, slick and charming. Add that to the medical degree and a quite ludicrous range of hobbies - he is an expert in antique bronzes, Napoleon Bonaparte and, according to his website, "an accomplished oboist, performing publicly from time to time" - and he's in danger of being irritatingly perfect. But he isn't irritating. How very irritating.
Today, however, we are meeting to talk about the impact the digital world is having on the lives of teenagers. From anxiety about sexual performance to mental health problems, increasingly, he says, the issues brought to him by young people share a common root cause: growing up online.
"It's people in their late teens or early 20s, really struggling with self-esteem issues, body-image problems, that kind of thing," he says, "and in a lot of cases it's really because of the digital world."
Jessen, or Dr Christian, as he is known to viewers, decided not enough was being done to prepare children for safe, responsible use of the internet and social media. So he is having a go himself and has written Dr Christian's Guide to Growing Up Online, which he calls "the modern puberty book, in a way."
Designed to appeal to readers aged 10-plus, it has been produced in conjunction with international anti-bullying charity Ditch the Label, which gathered dozens of real questions sent in by real children and had Jessen answer them.
They range from basic privacy advice ("Is it safe to include personal info on my blog?") to modern versions of age-old issues ("A stranger on Facebook wants to meet up, should I go?").
He is realistic about the fact that the internet, apps and social media are here to stay, so instead of fighting them, we ought to teach children how to use them responsibly. "It's like talking to your kids about sexual health. Do it as early as you can. If you make it a secretive, odd thing, that's when children turn to porn, which can lead to all sorts of hang-ups."
His advice for parents, who he acknowledges are the more likely prospective reader (it is, after all, a book), is to use technology alongside their offspring.
"Then you can show them what's good and what's bad. Pull up some ridiculous images and show them what can happen when it isn't used properly. You have to give them the chance to make an informed choice," he says.
The theory makes sense. But mums and dads are unlikely to sit with their 12-year-olds and watch, say, hardcore pornography.
"And why not?" Jessen hits back, with a shrug. "Make kids cringe and squirm. I think it'd be very helpful in sex education to show the distinction between porn and sex as you have it. Most parents won't have the gumption, but at school that could be a good lesson. Not full-on porn, but images, for example, and then they could discuss whether that's a good thing or not. Get them to watch this video of a man being fairly aggressive to a woman in porn and talk about that. Parents would be in outcry, but so what?"
Jessen, who lives with his partner in West London, came of age before digital culture, but doesn't believe it's all bad. Growing up gay, especially at boarding school, he had "few points of reference", for instance, which the internet now offers.
"We talk a lot about toxic masculinity, and there are still lots of boys who think they don't fit in with the idea of what a boy is. I didn't - I don't think most gay boys do. That's the great thing about the online community. There's a dark side and a light side," he says.
"It makes you feel less odd. In my day you didn't see any of those comforting points of reference, implying you should keep quiet about it. I remember one teacher at my school saying, 'I thought [gay] people like that shot themselves' - but he was in the war and quite shell-shocked, so we'll forgive him ... "
Does he have sympathy with kids growing up these days? He drums his fingers on the table. "Not so much sympathy, no," he says. "We just need to focus on making sure we're teaching children the important stuff. Things have changed dramatically in the last 10 years, and we've got to catch up."
Lowdown
Dr Christian's Guide to Growing Up Online (Scholastic, $18) Ditch the Label: ditchthelabel.org