Bridget Jones is not alone in turning [?] self-help mantras to boost her spirits, but a study warns they may have the effect.

Canadian researchers found those with low self-esteem actually felt worse repeating positive statements about themselves.

They said phrases such [?] "I am a lovable person" only helped people with high self-esteem.

The study appears in the journal Psychological Science.

A UK psychologist said people based their feelings about on real evidence from their lives.

The suggestion people should "help themselves" to feel better was first mooted Victorian Samuel Smiles 150 years .

“ Repeating positive self-statements may benefit certain people, such as individuals with high self-esteem, but backfire the very people who need them the most ”

His book, called simply "Self Help", sold a quarter a million copies and included guidance such as: "Heaven helps who help themselves".

Self-help is now a multi- pound global industry.

The researchers, from [?] University of Waterloo and the University of New Brunswick, asked people with high and [?] self-esteem to say "I am [?] lovable person."

They then measured the participants' moods and their feelings [?] themselves.

In the low self-esteem group, those who repeated the mantra felt worse afterwards compared with others who did .

However people with high self-esteem [?] better after repeating the positive self-statement - but only slightly.

The researchers, led by psychologist Joanne Wood, said: "Repeating positive self-statements may benefit certain people, such as individuals with self-esteem, but backfire for the very people who need them most."

However, they say positive thinking can help when it is part of a broader programme of therapy.