I'm no fan of fad diets, but a lot of Westerners have a real problem with simply not knowing what hunger feels like.

A lot of people are so habituated to large portions and frequent snacking that they're never meaningfully hungry, just somewhere on the spectrum between "reasonably sated" and "physically incapable of ingesting another morsel". Their eating habits have fundamentally broken the connection between food and sustenance. They've lost the ability to usefully distinguish between the body's natural hunger signals and other motivations for eating like habit, boredom and emotional self-soothing.

I'm not wholly persuaded by the claims made about the health benefits of intermittent fasting, but I do think it's a potentially useful psychological experience if you have a problematic relationship with food.