Well at christmas I was 17 stone and I have followed the Fast Diet 5/2 diet. It basically is eating 600 calories 2 days a week and eating normally (not pigging out) the otherdays. I have lost 18lbs and I am now 15 stone 10 I started it on the last week of January and have had a couple of days off it due to being on holiday and my wedding anniversary.
Clearly this has worked for me, but as Mercury Grey Minter has said I would check with your GP first.
Best of Luck and stick at it. I am so happy with the difference it has made to my self esteem and my ability to do more physically.