Therefore it would be entirely reasonable to suggest that if the gluttonous ceased stuffing their faces with calories they do not need but merely "want" because that cannot stop themselves then there would be, at least in theory, a great deal more sustenance available for billions of people who are in greater need.
That is only a theory. It is more likely that if all the rich fat people (who are the ones who can afford to fly) decide to eat less then food production will fall as the hungry people cannot afford to buy it.