protein shakes can be good IF u exercise enough otherwise the extra cals will just go to your body.
What brand were u looking at?
were u thinking as a snack or when u exercise?
With ur bmi being pretty good, where is the weight ur trying to lose coming from ie do u need to lose some more cms off around ur abs, legs, butt etc??? cause maybe u could do some more exercise focusing towards the area u would like to look a bit toner.