Protein (and fat) are more satiating options in general, which can actually lead you to eat fewer calories in the course of a day anyway.

If I have a protein rich and fatty breakfast, which is rare as I don't often eat breakfast, I am often not hungry the rest of the day.

Whereas if there are carbs, or at least a large portion of the meal is carb dense, I am usually hungry again an hour or two later.

If I eat a meal that is almost entirely vegetables or leafy greens, I am hungry within the hour and any fasting from there (say, overnight) becomes an unenjoyable experience.

Likewise, fasting in general makes me feel worse if I am doing it off of those types of foods, whereas if I fast after eating meat then I am not as grumpy, and I don't feel sick from hunger or as weak.

TL;DR: Meat good, vegans weird.