I've lost a small amount of weight whilst still entirely eating bread this year. The only thing food groups have to do with it is how filling everything is
> 99% of its dietary weight loss effectiveness is because fat is filling
This is pretty easy to disprove. It's not at all that fat is more filling.
Once your body starts to burn it's own fat you no longer feel like you're starving. Anyone whose fasted could tell you that, never mind been on keto.
The starving feeling comes from the period in between where your body is waiting for more carbs before finally switching to fat burning mode.
So it's not that fat is filling. Carbs are filling, too. It's just that when carbs are burned, there's nothing to replace them with, but when the fat you've consumed has gone through your system, and your body is already in Ketosis, it doesn't feel bad because there's weeks and months worth of food already on your body to burn.
I like of feel like it's easy to "prove" the opposite.
If I eat a meal comprised of fat and protein (2 fried eggs with some cheese, for example), I'll feel sated and won't feel hungry again for up to 5 hours.
On the other hand, it I eat a bowl of pasta, I'll feel very full immediately after eating, but am guaranteed to feel hungry again in ~2h.
I firmly believe that fat and protein are more "filling" than than carbs, and many people have shared similar anecdotes.
Even with ketosis (a real thing), 99% of its dietary weight loss effectiveness is because fat is filling.