One of the great misconceptions in life, applied to literature but not to other art forms, is that reading for the sake of it is a good thing. No sensible person would suggest that listening to a Ronan Keating album or attending an exhibition of watercolours by cats would be a productive use of one's time. Yet we constantly apply this illogical dictum to reading.
Let's clear this up right now: there are many more worthwhile things you can do with your time than read Irvine Welsh's The Sex Lives of Siamese Twins. Learn to ride a unicycle, for example. Clean out the garage. Count your fingers and toes and make sure they're all present.
Perhaps it's an unfair comparison, but I came to this book having just read new novels by Mary Lawson and Damon Galgut, both of which reminded me how deeply the novel form can contribute to our understanding of human nature and how elegantly constructed sentences can turn words on a page into something sublime.
Reading Welsh after this was like being roused from an afternoon of joyful and soul-enhancing lovemaking by the sounds of a Metallica album, played backwards and at top volume.
The cacophony begins as we are introduced to personal trainer Lucy Brennan, "a zealous warrior against the plague of obesity which is swamping our nation in blubber", who prevents a shooting on a Florida causeway by disarming the gunman while being filmed on a mobile phone by Lena Sorenson, "203lbs . . . carrying an extra eighty-odd pounds of fat on her gut, her ass, her thighs".
The two are drawn together, and as Lucy tries to improve Lena’s unhealthy lifestyle she dreams of turning her act of heroism into television celebrity via “a fitness-slash-lifestyle show”.
There is no shortage of agents and producers eager to sign her up while there’s still 10 per cent of her 15 minutes to cash in on, but when Lucy contacts those already prospering in the field they are less eager to help. The American pie, after all, contains only so many slices.
The contrast that Welsh draws between Lucy’s devotion to her health and Lena’s equal dedication to her eating sometimes works well, and if the women seem like caricatures, then perhaps that’s the author’s intention.
It’s much easier, after all, to make the fat girl vulnerable, needy and slightly psychotic and the skinny girl obsessive and sexually promiscuous with both genders.
As in cinema, which is almost exclusively the domain of male directors, women in these types of novels are always willing to engage sexually with other women in graphic detail while the men remain rigorously hetero and would have an anxiety attack if a handshake went on too long.
Occasionally dropped into the action is a recurring news story of a pair of Siamese twins, one of whom wants to have sex with her boyfriend while the other doesn’t, a moral question – slut v virgin – that divides the nation’s opinion. It has little to do with anything else that’s going on, but at least it gives the novel its commercially titillating title. Handy, that.
In the past Welsh's novels have relied considerably on dialect, most notably in the Edinburgh-based Trainspotting, Porno and Skagboys.
Moving outside of his comfort zone to Florida offers him a chance to try something different, and, while redolent at times of Elmore Leonard and Carl Hiaasen, both of whom also set their fiction in the Sunshine State, it does at least sound realistic even if your taste doesn't run to 468 pages of someone screaming at you in an authentic manner.
As Lucy's influence on Lena leads her into Single White Female territory, she is provoked into action over the many troubling relationships in her life, particularly with her parents, "small-town, God-fearing people". But this in turn leads to moments when one cries out for the editor's red pen. "When you suffer from depression," Lena opines, "you just have to hang in there."
Oh, to have such a deep insight into the difficulties facing mankind. And this from a writer whose "Choose life. Choose a job. Choose a career" monologue once suggested an electrifying voice in fiction. In the early 1990s, after all, it was a badge of honour for any self-respecting student to carry a copy of Trainspotting and do their best to sound like Renton and Begbie, just as it would become similarly fashionable to parade the tedious and self-consciously outrageous work of Chuck Palahniuk or Bret Easton Ellis.
But when you wish the so-called voices of a generation would just pipe down and lie quietly in a dark room until the urge to write passes, it does feel as if they might be a little past their sell-by date.
I'm sure many people enjoy novels like this and consider them hilarious, anarchic and a kick to the backside of the literary establishment. I wouldn't care to know any of these people, but I dare say they're out there. After all, as Abraham Lincoln so memorably put it, people who like this sort of thing will find this the sort of thing they like.
John Boyne's ninth novel for adults, 'A History of Loneliness', will be published in September