From what I can see you'll be fine. Especially agree with Yersinia, you ran a marathon not so long ago and its only 2 stone. When I started running I was 4 stone over my ideal [and still 2 stone over now] and I just made sure I was careful in not over doing. As you point out, running will help get the weight off and will, in the long run, be good for you so I'd go for it.