Her busy lifestyle undoubtedly makes it easy to keep the pounds off.

But Victoria Beckham looked alarmingly thin pictured near her Los Angeles home at the weekend.

The former Spice Girl who has now carved out a successful career as a fashion designer wore a low cut jacket which did little to disguise her slender frame or her ribs which could be seen poking through her skin.

Skeletal: Victoria Beckham's rib cage shows the extent of her latest weight loss

An onlooker who saw her leave the LA party where other guests included Peaches Geldof and Gwen Stefani, said: 'Why Posh chose to wear such a revealing jacket which only served to display how flat-chested she has become is anyone's guess. It really was not an attractive look at all. It is a look which will do little to stop talk of her being unhealthily underweight.'

The fashionista stepped out in a £595 pair of suede Christian Louboutin 'Maggie' stilettos, with a 5 1/2 inch heel.

Victoria's weight first hit the headlines ten years ago and saw her dubbed Skeletal Spice. Since then the 35-year-old's appearance has fluctuated from being skinny to very skinny.

'Not an attractive look': Onlookers in Los Angeles said Victoria's skinny chest would do little to quash talk of her 'being unhealthily underweight'

Occasionally, she gives the impression of having put on more weight by trussing herself up in gravity-defying push-up bras.

Victoria has often cited the pressure of looking after three children and juggling a hectic work schedule for the reason she struggles to put on weight.

She is constantly pictured on the go, jetting most often between Los Angeles where her and husband David's three boys are in school, to Milan where David plays football and Britain where her parents and sister live.

Victoria, who appears as a judge on American Idol, has been slated by the US media in recent months for her slenderness. In the past, she has featured on pro-anorexia websites and admitted that during her time in the Spice Girls she 'came close to' having an eating disorder.

However, she recently defended fashion designers who use stick-thin models to promote their clothes.

She told New York-based TV show The View: 'Most of these girls are naturally thin. And I don't think we should be discriminating against someone because they are too thin or too curvy or too large or whatever it is.'

A spokesman for Victoria was unavailable for comment last night.