The NHS advisory organization revealed in draft guidance for new mothers that losing the extra pounds pregnant women gain under the myth "eating for two" will take time and they should not try to crash diet.

It said that "celebrity claims of unrealistic rapid weight loss" puts women under additional pressure at an already stressful time.

Heidi Klum, the model, was back on the ramp just six weeks after the birth of her fourth child last year. Even Myleene Klass, the television presenter, was successful in grabbing back her svelte appearance just three months after Ava was born; however, she said it was simply due to breastfeeding and clever dressing.

In addition, advice on weight management during pregnancy emerges as the number of obese mothers is soaring, with almost 25% women being obese and a further 33% overweight.

The management says women should be advised that being fat renders their baby at risk and other birth complications, but not told to lose weight.

The guidance is aimed at healthcare professionals involved in the care of pregnant women and after birth to help them give consistent messages and use methods that are known to work.