Whatever the methods are,you should follow it forever otherwise,if you suddenly stop doing,your body will get it all back and then some!Look for e.g. on ex-athletes.They all on some sort of diet,but when they retire, only a few are still in shape.The majority gain some rolls around their wastes.
Yea. You can't just go to doing whatever. Even people that were not ex-athletes show that!
But, you gained the weight cuz you killed your metabolism by starving yourself. So.. if let's say your metabolism was at a base of 2500 calories (for simple numbers) and now you starved yourself for 4 months and your metabolism is now at 1500 calories. Well... when you start eating 2500 calories again .. the 1000 extra is extra and will be stored until your metabolism takes off again and readjusts..
That's not intermittent fasting!
), your body starts burning fat because you had enough protein to not have to break into muscle.. cuz your fast wasn't to that point