alt Hacker NewsThat is not correct.
People lose fat on calorie restricted diet. How will you get to it, either by counting them or by improving metabolism or by changing insulin levels, is a different thing.
Vegan or keto diet can both be calorie restricted, as much as any macronutrient mixture. However, it doesn't mean its sustainable. If you are hungry all the time, you can stay on the diet for some time, but not forever. Since insulin is the primary storage hormone, reducing it will make you less fat (just look at type 1 diabetics). We now know that carbs are the highest promoters of insulin, that fat has 0 influence, and protein some. We have drugs like metformin or GLP-1 that brute force some of it and they are working.
So, we know that sugar is mostly bad and that fat and protein are not. Ofc, some fats are bad for other reasons (by promoting inflamation) but that has nothing to do with obesity.
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.