Picture the scene: you’re at a friend’s house and have just dined on sustainably fished Cornish mackerel with organic flower and kohlrabi salad, when the host excuses himself. But instead of heading to the bathroom, he slips out the back door. It could be the Fairtrade wine going to your head, but you could have sworn you just spotted him undoing his flies in the garden. Hang on a minute, there’s steam rising from the lawn. “Harry’s doing his bit to save water. No flushing needed, you see,” explains his wife, as you pray the flowers in your dinner weren’t home-grown.

Unappealing it may be, but this scene is being played out in this country’s more extreme eco-households. Hessian shopping bags and recycling boxes no longer cut it for these greenies, whose environmentally friendly behaviour is bordering on the bizarre. They have been identified as “carborexics”, or energy anorexics, in a report that found evidence of a whole gamut of strange behaviours masquerading under the eco label. Aside from urinating on the lawn, carborexics re-use Ziploc bags for up to a year, weigh their household waste, and eschew heating in favour of layers. They’ll routinely sleep in huddles to keep warm at night, toss biodegradable nappies on the vegetable patch and try to spend less than £500 per year on consumer goods. The temperature in their homes will often be less than 16C in winter, and many run their cars on waste oil. Failure to be as green as could be leaves them wracked with disproportionate guilt.

“My husband and I are so energy conscious we went without heating of any sort for four years,” says Penney Poyzer, a 48-year-old TV presenter and author, who lives in Nottingham. “We’ve just installed a wood-burning boiler, so now the challenge is foraging for wood — we recently took 40 pallets from a building site. I’m not embarrassed to say that we unearthed most of our furniture from skips, or that we pee on the compost heap. Many of my friends go in a bottle at night, then pour it on the garden come morning.” Before you dismiss Poyzer and her husband as eco-warriors: she’s actually a glossy haired brunette who loves nothing more than throwing a dinner party (albeit at a table rescued from the refuse), while he’s a sharp-suited architect. “People are often surprised by the lengths we go to,” she says, “but we’re devoted to nature. Being green is our passion.”

Passion? “Try evangelism,” says David Zucker, a partner at the public-relations firm Porter Novelli, which has just carried out a study into the phenomenon in the United States. Zucker reckons up to 7% of Americans fall into this category, dubbed the “dark greenies”. “They believe the future depends on them, and see themselves playing an important role in our collective salvation,” he says. “Some of them see their role in avoiding disaster as being so crucial that they tend towards extreme and intolerant attitudes regarding their own and others’ behaviour.”

“Being green has taken over my life,” admits Madeline Carroll, 28, from Stroud. “I feel constantly guilty about the state of the world, and I inflict that guilt on my boyfriend, too. If he doesn’t use the eco setting on our washing machine or refuses to re-use one of the freezer bags I’ve washed a zillion times, I freak out. I really infuriated his parents recently when I went round there and turned off all the switches on their Sky box, TV and DVD. It took them an hour and a half to re-programme everything, but I couldn’t sleep knowing they’d left them on standby.”

Georgina Firth, a 34-year-old PR from Hove, experiences similar pangs of disquiet if she doesn’t stick to a strict eco code. “I’m so worried about the ozone layer that I’ve turned my fridge off. Now I line up my milk, cheese, yoghurt and vegetables on my balcony. Even though there’s every chance the seagulls will eat them.”

Dr John Morgan, a consultant and lecturer in psychiatry at St George’s Hospital, London, can see a darker force behind the zealous actions of carborexics. “Being green is associated with moral goodness,” he says. “Obsessive-compulsive disorders often occur in perfectionists who are drawn to a moral cause. Two hundred years ago, that obsession might have been with religion — now it’s with the environment.” Spreading the word is also an important mission for them. “They have strongly held beliefs on how a company should act, in terms of ethics or energy efficiency,” he says. “If they perceive a firm is misbehaving, they believe it should be ‘punished’ by being avoided, and spread the word about these sinners to their social networks.”

But could those intent on saving the planet really be in danger of losing their minds? It’s unlikely, says Paul Wheble, a cognitive behavioural therapist at the Centre for Anxiety Disorders and Trauma at King’s College London. He points out that such behaviour only qualifies as a disorder if it interferes with a person’s life, leaving them unable to study or work, or by causing their relationships to break down.

Nevertheless, carborexia does seem to be more than a passing fad. “An obsession like this comes to define a person,” says Morgan. “If you go to the nth degree with this, it’s going to be difficult to shake. For many, this will be a life-long pattern of behaviour.” A word of caution for alfresco urinators in it for the long haul — the grass isn’t always greener.

Ten signs you're too green

1 You use old bath water to boil your pasta

2 You are brilliant at dressing in the dark

3 You only flush for number twos

4 You once served up roadkill to guests

5 You re-use empty crisp packets as wrapping paper

6 You consider hats and organic beer to be central heating for adults, as in, “drink yourself a sweater”

7 You think your compost heap is a great design feature

8 You buy vintage underwear

9 You’re experimenting with silk worms

10 You smell similiar to your organic window boxes (when not in bloom)

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