We can't just go by a picture. How much do you weigh?
Depending on your frame size, you need to lose between 160 and 200 lbs.
Here's a bit of a height/weight chart that pertains to you.
Height Small Frame Medium Frame Large Frame
5'9" 142-151 148-160 155-176
You look to be medium to large frame (?), so I'd say if you got down in the 170 range, you'd be doing pretty good.