That's a good question but it all depends on what your Body Mass Index is now and what it needs to be. Rather than set a target weight, most Dr's give you a BMI target to reach. It might be that you don't need to lose say 2 stone but get down to a BMI of X and to achieve that you only need to lose 1 stone or such like.
It's not done on just your weight and height...So like I'm 5ft 5" and 17 stones and I have a BMI of 40, I need it to be 35 and so I have to loose around 3 stones apparently.
Also take into account your build when deciding how much weight you need to lose.
You should ask your GP to calculate your ideal weight for you specifically.
JJ
