Posh will fatten up to try for baby No4

At the age of 32, she has the waist measurement of a seven-year-old child.

And until now Victoria Beckham's frame seemed to be getting thinner by the day.

But after stern words - and strict instructions - from her husband David, the former Spice Girl is on a mission to 'fatten up'.

With expert nutritional advice at his fingertips, the Real Madrid star has put his wife on a carbohydrate-laden diet.

It is hoped that by putting on more weight and increasing her body fat percentage the singer turned fashion designer will be able to conceive the couple's fourth child more easily.

If women are too thin, they can stop menstruating - meaning they cannot become pregnant.

Strict diets can also result in low dietary intakes of nutrients essential for pregnancy. A low body fat percentage may also harm fertility. In normal adult women, fat comprises about 28 per cent of body weight and if it drops below 22 per cent, ovulation may stop.

'David knows that Victoria struggles with her body image and thrives on being thin - but he is desperate to see her with a few more curves,' said a source close to the Beckhams.

'David has pleaded with her in the past to put on weight, but now he's finally taken serious action and given her a diet plan to ensure that she fattens up.

'Her new diet will be very carbohydrate-driven, and rather than picking at sushi and steamed vegetables, she will be tucking into lots of bread, pasta and brown rice - even crisps if that's what she fancies.

'Victoria's agreed to go along with it because she and David are happier than ever at the moment and also because she is desperate to conceive. After having three sons, who they love dearly, both of them would absolutely love a little girl to dote on.'

The regime comes just a month after the Mail revealed that she had become a 'thinspiration' for anorexics. It also emerged that she had to have her clothes altered to stop them from swamping her rail-thin frame.