For years, I assumed the same thing, that "fasting" meant experiencing significant hunger. I always associated it with going entirely without food for some vague amount of time that was probably some consecutive number of days. But three weeks ago, after some Googling, I began what is called 'intermittent fasting'. Since it's only been three weeks, all I can say personally about the benefits is that I'm still doing it and have no plans to stop in the future, but I
can say that by the third day, the hunger issue was negligible.
The first Google result on the term is pretty good: http://jamesclear.com/the-beginners-guide-to-intermittent-fa...
At its simplest, for men it means eating all your food for the day in a roughly eight-hour window, often noon to 8pm. (There is apparently some scientific thought that women may have significantly different needs; I really can't speak to that.) In practical terms, this translates to "skipping breakfast" and avoiding midnight snacks. This turns out not to be that difficult, but has definitely had an positive impact on me, so far. Discomfort-wise for me, I tend to get a bit of a rumbly tummy around 10am, but generally it subsides pretty quickly and even by 11am I can easily go for another couple of hours without even thinking about lunch if I get busy. It is far from constant hunger. (But I won't lie and say it's zero... just, negligible. Literally. It can easily be neglected and it will in fact go away.) I can also say that I'm hardly watching the clock in the evening and trying to judge whether it's the crack of 8pm yet or not... I often eat at noon-thirty or 1pm and then dinner at 6pm and am done thinking about food for the day, without any willpower expended. It just happens.
I say this mostly to point out to people that there is something to investigate that they may have misconceptions about, as I did. I will fully and up-front admit once again I am not in a position to extol its benefits particularly. (I like to do something like this for at least a couple of years before I do that.)
(But I will go slightly out on a limb and say that I would not be all that surprised to discover that "intermittent fasting" has somewhere between 80-120% of the benefit of the scientifically-studied high caloric-restriction diets, with much lower willpower and discomfort costs. It turns out that if you dig into those, we've really only studied "normal (modern) diet", "heavily calorically restricted", and sometimes a particularly unrealistic fasting schedule (see link), so if you're interested in a point in the middle of the two we've studied, you're sort of scientifically on your own. Hence the possibility I cite of 120%; currently it would fit the two data points we have just fine for it to turn out that "caloric restriction" isn't the optimum and is in fact overshooting.)