Baby Weight Shedders

I recently came across a picture of Christina Milian and was shocked to see that she had shed her baby weight so fast (either that or she was wearing some extra strong Spanx or doing some hard core sucking in).

She looks amazing.

It got me thinking. How is it that these women are able to drop masses of weight in short spaces of time, yet everytime I walk down the street I am cornered by women, that have been rocking their baby weight for years. What are these baby weight shedders doing right?