Many years of bad habits to correct HELP

[lookingforbetterbod]

Hello
I am new to this site and need your help as I have many years of bad habits to correct I am currently 210 lbs at 5’ 11” and need and want to build muscle.
I only eat 1 meal a day and have eaten this way for the past 25 years after loosing 75 lbs in 2 months. I have been afraid of putting the weight back on I know this is not healthy and want to correct this as well but at the same time I do not want to gain any more of the weight back, muscle would be fine but not fat I feel most comfortable at 180 –185 lbs but at that weight I am flabby.
I have always been interested in lifting weight but have been told by my Doctors not to because I have had 2 lower back surgeries and 1 neck surgery they said it could damage my spine more. Now 20 + years later my new younger Doctors have told me lifting weight would be good for me just not to try and press a like 300 lbs of weight they said building up my abs and back muscles would do wonders for me. My question is how do I correct all this and where do I start. I thought it would be a good start if I could tighten up my abs and upper body and see where it goes from there. To get started I have just purchased a home gym and 400 lbs of steel plates. Where I live the winters are long and cold so I thought for the next 8 months Sept. – April this would give me a head start and the motivation I need. What about diet, protein, nutrition, vitamins and how many times a week should I do weights?
Thanks in advance for any and all help much appreciated.