Weight loss is dependant on using more calories than you take in. So the answer will depend on diet. If you are eating Maccy D's and drinking like a fish, and have an otherwise sedentary lifestyle, then its probably not enough.
However if your weight was stable, you haven't changed your diet, and this is excercising is new to your life, then yes you'll probably lose some weight. For myself (a bit over 13 stone), a 4.5 mile run would burn off around 600 calories.
My diet is the same, I do eat junk here and there and pig out..
I used to just run 4-5x a week (5milers) and within the year I lost near a stone, now because of other commitments I'm only able to able to 2-3x a week. so I run tiwce a week and gymn once a week but I find im not losing any weight now:S