I've been doing this for about 5 years now. I was a bit podgy round the middle and my Doc suggested it (it worked for her).
After dinner between 6 or 7pm I don't eat anything till about 1pm next day (so about 18 hours). Just drink plenty of water and some coffee.
Initially I slowly lost about 20lbs (9kg) and since then I've stayed pretty slim, well within my BMI. So it's worked for me.
Apparently its good for your metabolism also.
Here's a video of a Doctor talking about it (sorry about the vocal fry she has and overuse of the word "like")
Does anyone else do this ?
https://youtu.be/i-hCUkAsbpU