Losing Weight

I have registered at my local doctors but in the consultation I got put into the obese catergory & because I have 2 diabetic parents have been told to lose weight which is fine with the execption that I'm supposed to lose 5 stone to fit into the height to weight ratio according to health guidelines. The problem comes with the fact for me to lose that amount of weight I would also need to lose muscle as well as the fat that I have to become 13 stone, so diet, exercise & muscle wastage. I know I can do the first 2 but how am I supposed to do the latter I'm not entirely sure. I am back on a healthier diet than what I was as since Christmas I have been eating junk. My main weakness is for snacking & ale I need to stop doing both but need to have the will power. I will allow ale on mootnights but think the drinking at home must be cut down dramatically, plus I'm not sure I'm drinking enough water anyway so may be able to kill two birds with one stone. I'm also putting down the rule of if the sweet treats are not home made they don't get eaten & one more thing I need to do as far food is concerned is to cut down on portion size my family are large eaters, as to whether I can do it is another question, but what I do eat is a lot healthier some people I know as I don't eat processed food as a rule as I love cooking from scratch & I love fruit & veg & generally crave it if I haven't had enough of them. I also need to connect the the Kinect back up on my Xbox too so I can increase my exercise from walking 8.5 miles on work days to adding more cardiovascular exercise to it too, though when the weather perks up I have a fair few heavy jobs on my new veggie plot & in my back garden so that will be a boost too. But where the weight loss scale does fall down is on muscle as last time I lost the inches around the trunk of my body my weight went up, so I could have the perfect six pack & still be called obese, what happens if/when that happens? I guess I won't know but I would question it seeing as though most rugby players have a bmi that suggests they should have difficulties walking. Wish me luck & I shall be hitting the spell books for an extra boost when the moon has changed to waning.