I lost 12 lbs and about 2 inches off my waste. Conversely, I knew someone who lost 15 and only 1 off her waist. It does vary vastly from person to person.
If actual loss of weight is not an option, shapewear certainly is. For the bust, try using a sports bra in lieu of a normal bra and, as mentioned before, corsets are great for adjusting waist size. When I was at my heaviest, I wore a corset under some of my lolita dresses on the rare occasion I would wear them.
Be wary of corsets, though, because they shave off inches but can add a bit of bulk. And make sure you get an acutal, steel-boned one, and not just a "fetish" corset.
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oropher [the silmarillion]
You're so far in the closet,
you're in Narnia!