Ok First I Am 52 Years Old And Obese. I

Ok first I am 52 years old and obese. I am 5'7" weigh 313 lbs. I was addicted to prescription pain pills for eight years. The doctors had me on 28 different pain pill, muscle relaxants etc. Although I am severely overweight I hate eating. I have to force myself to eat 1 meal a day. That being said my metabolism is slow, I found out today my left atrium is enlarged and I have severe edema in my lower legs I have a history of blood clots. 1. How can I make my metabolism speed up 2. What kind of diet is there That I can lose wight fast the first month then to continue losing 2-3 lbs a week?