I'm a historian by trade, and it occurred to me that this UN Report recommending a Vegan lifestyle in order to ease the drain on world resrouces might have some historical context. So I started thinking about how I could do that for you, and the name Thomas Malthus popped into my head. Malthus was a British scholar and reverend who lived in the late 18th and early 19th centuries. He published some controversial (then) stuff on popoulation and demographics.
His demographic assertions were in a work called "An Essay on the Principle of Poulation." He asserted (WAY oversimplified here) that the population would someday overcome the Earth's ability to sustain it. In essence, we would outgrow our planet. He wrote: "The power of population is indefinitely greater than the power in the earth to produce subsistence for man"
Isn't that what this report is saying in a way? That our incessant need for animal products is creating a drain on world resources to feed and grow those animals to provide that food for the population that we are actually damaging the planet's ability to sustain us?