Why is my wife so vain?

My wife is usually a beautiful lady but i admit she has put on a few pounds and has quite of a belly, which she needs to get rid of, but her breasts are great and round. The girls in my house have a clothes spending bill a month of �150 between them to save money but this month my lady has gone over the bill by �64. This is unacceptable it teaches my daughters nothing, so to teach her, her wrong doings I removed half her wadrobe and put the rest at my brother and i left her with clothes I feel are good and have gave her at least five outfits but she has been very vain and has gone so far as to sneak clothes in, I have removed them now to and i will give her other clothes back when shes ready but she is to vain, how can I change this? nothing is working.