If you can lose 6 stone chances are you are a touch on the heavy side for running, you will knacker your knees and then where will you be ? Long walks, lunchtime walks, walk to work until you aren't carrying too much weight.
Get a road bike, long steady miles, build up to hilly rides.
Eat lots of raw carrots, diet coke worked for me. Drink LOTS of water it keeps you full, you can mistake dehydrated for hungry.
And you have to want to, have a look at why you eat so much, what are your triggers ? Do you watch loads of TV ? (makes me want to eat for some reason, probably subliminal messages from the aliens)
This is experience talking - I went from what I think was around 7 stone 2 to 15 stone (I think in metric) to bang on 8 to a more healthy weight these days, not got on the scales just diet a bit when my fave jeans get a bit tight.
Some folk swear by hypnotherapy, other folk go for the powder sachest diets, none of these seem like long term solutions, which is what you really want.
Good luck, and don't be tempted by a quick fix, it's about lifestyle change.