Welcome to the post-Bridget Jones generation of heroines, invariably single, of fluctuating weight, fond of cardigans and more familiar than is strictly healthy with Saturday night TV schedules. Nothing very "post" about that, you might say. But if Bridget Jones appealed as Everywoman, Jane Green's Jemima J (Penguin, pounds 5.99), Isabel Wolff's The Trials of Tiffany Trott (HarperCollins, pounds 5.99) and Clare Naylor's Catching Alice (Coronet, pounds 5.99) are ambivalent about the extent to which they want their readers to identify with their characters and crises - be it blowing the fuses with the hairdryer, or the all-absorbing search for a man.

Take Alice Lewis, the heroine of Naylor's second novel. She "wanted to live in an Aga Saga. She longed for a refectory with a crumbling wall and dogs." This she proves by entering a "Jane Asher tea shop". It is an unlikely scenario in which the impression that the character is being made to play a part exceeds what that part reveals about her. This forbids our identification, despite the assertion that "Alice is a girl like any other".

These novels seem to want to say both "I am really like that" and "that is not really what I am like" - to express a need to be both normal and a little crazy, to validate and repudiate the "trials" they describe. At times, and this is particularly true of Tiffany Trott, this ambivalence borders on cynicism - as if Wolff wants her protagonist to poke fun at the book's own characterisation as cartoonish.

Indeed, there is much to be cynical about. Weight, by nature a great variable, has a phantom quality in these novels. One minute Alice Lewis is over the moon to discover that she can fit into her friend's trousers, the next she is said to possess "soft marble white curves... [that] defy any amount of time spent on the treadmills". Then there is Jemima J, whose eponymous heroine sheds six stone before finding her true self as "a curvy size 12".

Tiffany, Alice and Jemima are all bombarded with images of consumption. Just as Alice chooses a Jane Asher shop, Tiffany doesn't drink coffee, but Nescafe. Moods are described in terms of what can be suitably consumed at any moment. Thus Alice and her friend Tash watch Reservoir Dogs when "the psychopaths in their souls" have been "stirred up by evil males". However, as well as being victims of an image bombardment, you will notice that all the heroines' names possess a catchiness which is itself commercial. When, despite the trials, each finds a man and comes good, their success is partially the commercial success of living up to their fantastic names.

So doing, however, they seem to sell out. They lose the sense of failure and of coerced role-playing which seemed to be the characters' main points of identification with their readers. Transformed by success, a strange thing happens to these heroines: they become, for the readers, the equivalent ot their own formidable best friends.

Best friends tend to be a motley crew in this genre - always slimmer, more successful and prettier than the heroines. This new relationship is affirmed at each books' close, usually in a trite passage of reflection. "Fairy tales can come true," writes Jane Green, "if we trust in ourselves, embrace our faults and brazen it out with courage, strength, bravery and truth, fate may just smile on us too." Just what we needed. Another role model.