......... the rule of thumb is: an acre of land, planted with assorted vegetables, will sustain a family of 4 for a year. The same acre, with livestock on it, will support the same family for 6 months or less.

I guess this lies at the heart of my question. Converting plant protein into animal protein is a luxory for lots of people, it's a waste of protein and leads to massive habitat destruction. If we do not limit meat eating we will have many less animals.

Convincing most people to give up meat altogether is very difficult.

I suppose I am also irritated by people who in a social situation will be quite verbal about not eating food with the smallest bits of animal in it. I know I have no right to be irritated by this or by any other food taboo.

To re-state my original question:
In terms of cruelty to animals and habitat destruction wouldn't 2 people eating half as much meat be as effective as one giving up altogether?