On veganism... I only know of one person who was full-stop vegan for more than 10 years. And even he had major health issues, due to absorption problems of some nutrients.

He found a source of said nutrients that works for him. Everybody else returned to a balanced diet.

I do understand that some people can function on purely vegan diet. However most do not.

could you comment on this then - http://www.ajcn.org/content/82/5/1011.abstract

P.S. I'm genuinely asking, most of my knowledge is borrowed from Leangains

Interesting — I hadn't seen that.

This shows that what is going on here may be more complex than first thought. (Maybe it is just a Pavlovian response.) It doesn't change the evidence that people and rats put on weight when drinking diet drinks – it shows that the reason why is still unclear.

<side note> I do worry how many medical papers are based on tiny samples. 5 seems very small to me (when I was doing drug research 100 was a small sample). </side note>