I've lost a stone, how long before I lose the last one?

[thisonethennomore]

Stupid question really.

I've been careful about my diet; 3 healthy meals a day, very little alcohol, no chocolate or puddings, masses of fruit & veg and I've increased my exercise. In the last 7 weeks I've lost 15 lbs and need to lose another 12.

My weight has plateaued and I can't sensibly eat less or do much more exercise.
I'm 5'9" and currently weight 10st 12 lbs.