@WithAFaeryHandInHand
My worry was based on the hypothetical scenario that the government might start recommending the likes of Atkins, which, without experience and guidance would I think result in people going bananas and eating ALL THE COWS
Atkins and his diet is much maligned. And the media is responsible for that, IMVHO.
His diet isn't about unlimited meat and no veg. It's a very carefully structured diet - but it's rare that I've seen or read about anyone following that structure properly. So I'd agree with you, that if people just try and 'do Atkins' without doing it properly, that's a potential nightmare!
And re sustainability - sorry, but I'm not going to give up eating meat or dairy. I don't consume massive amounts. Happily for me, there are plenty of other people going vegetarian or vegan (as reported in the paper this morning) for me to not worry about my consumption 
Oh, and I have two cats two. Sorry. Not sorry.