Don't know if this doctor is quackers but he has some interesting views on diet and stuff. http://youtu.be/DgbdNNfotwM
If that is a genuine quote from Haye, it only states that he will not eat meat. It says nothing about dairy products or even fish......
Aside from the ethical issues which is an argument that could rage forever there is simply NO credible scientific research that suggests eating meat is essential to achieve elite levels of either health or fitness. In fact, many top athletes hide/have hidden their Veganism in order to 'one-up' the competition and get a perceived 'edge'. Carl Lewis for example never spoke of it during his competing days......
Varying levels of $hit go on, some massively pretentious IMO and some genuinely respect-worthy. One end of the spectrum is to be Piscatarian (only eating fish as a meat) then there is Vegetarianism (only vegetables in diet), Veganism (no animal products in diet, clothing, manufacture methods or any consumable product used). Then the far end is Fruitarianism which involves only eating raw fruit which has already fallen from a plant/tree and which relies on it's fruit being eaten to spread it's seed. Things get a bit ****-a-mayme beyond a Vegan diet if you ask me but it's all valid.....