This is simple to show in a back of an envolope calculation: Around 3/4 of what you eat is used just to keep your body warm. So if you reduce your eating with 12-13% you have in effect halved your net food intake. Or if you increase your eating with 25% you have doubled your net food intake.
Of course it is not that simple, but it shows that variations in food intake have a significant impact.
Hm, reading the above I realize that it does not adress how this relate to the effect of excercising, but well. Maybe someone else could fill in.
... suggest that the size of servings is influenced by bad habits and by expectations from food sellers.
The human mind is actually quite deceptive, and exactly when you feel full when eating is in no way an objective, fixed norm. Search for bottomless soup bowl for an intresting experiment that shows how people are fooled to eat much more than they expect without notecing.
The fancy is indeed no other than a mode of memory emancipated from the order of space and time. -- Samuel Taylor Coleridge