I used to be 11.9 stone and I am 5'4" and I managed to lose 2 stone in 6 months. If you want to know how I did it just follow these steps.
So first thing I did was make myself a very strict diet: breakfast at 6:00 am which is always a protein shake and muesli
Go to the gym and follow the steps from your pt
Lunch at 1:30 pm which is always a salad
Then I go for a 5 mile run. It starts off hard but you get used to it
Then I have dinner at 8:30 which is normally some veg and some meat and some carbs
Then I do a few 'at home workouts' so things like pushups, sit ups and burpees. Then I go to bed at 11pm and then I get up at 6 and follow the steps again