FWIW, I've done a ~20 hour fast for the last few months.

Eating in a 4 hour window from 6pm to 10pm approx.

This diet isn't practical if you're doing any serious exercise, either in the morning, or late evening (during after the eating window), so I often have to cheat and eat lunch, or otherwise extend the window on days when I'm exercising.

Otherwise it's surprising easy to stick to with a coffee or two for comfort, and I've lost a significant amount of weight:

* It's hard to eat enough calories to gain / maintain my (over)weight in 4 hours, at least if I stick to whole, fresh, real food. Some days I can hit a ~1000 calory deficit according to my calculations.

* I find it easy to go to sleep on a full-ish stomach, which helps a great deal compared to other diets.