this has always been my problem for years 
I have got a sticky outy sort of a bum and a bit of a overhang tummy, which is now worse after 3 kids... It seems like they fit perfect then after I start walking around my tummy kinda flops out and then they fall down over my bum.
Where am I going wrong? Is it the wrong style of trousers or what? wierdly it is more of a problem with trousers than skirts?
Please help!!