Why does my body digest food so fast?

I do IF and while I try to keep it an 8 hour window it usually is like a 4 hour window. I just consumed 4200 calories in a time span of 4 hours and the feeling of being sated lasted maybe an hour.

For some reason meat does not sate me at all despite being pure protein and fat. If anything it makes me want to eat something like yoghurt right after to flush it away.

Also I find it kind of ironic that if I would eat 1000 calories worth of vegetables I would probably feel full all day because of all the fiber while 4200 calories of protein,fats and carbs makes me hungry again after an hour