All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
There is nothing wrong with your wife beautifying herself for you with what does not disagree with Sharee‘ah, with concealing her defects from you – so long as it is by your consent – and with practicing sport at home. Furthermore, to go on a diet implies no change in the Creation of Allaah Almighty.
Nevertheless, the flabby breast is, to be sure, of the Creation of Allaah, but He Has Made causes lying behind that flabbiness, including the woman's carelessness about herself, her physiological constitution and so on. The Fatwa you have referred to does not imply any absolute prohibition of having a breast lift; on the contrary, the case is explained in detail. So, please, read it carefully.Allaah Knows best.