Thing about the keto diet is that "hungry all the time" simply... doesn't happen. In fact, bigger problem for keto dieters tends to be being satiated all the time and consequently undereating.
"Hungry all the time" is actually vegan thing, but plants have so few calories and pass through so quickly that vegans end up being skinny despite eating literally all the time.
I think it's an adequate-good-quality-protein-consumption thing rather than a keto specific thing.
> plants have so few calories
You mean leafs, not plants? Cereals, beans, fruits and some roots have plenty of calories but your true fatty friends are all sorts of seeds and nuts. You also can buy their fat extract: oil.