The Doctor doesn't make too many major life decisions on Doctor Who. He's like Batman or Captain Kirk: Any character development will probably get rolled back at some point. But it's still kind of sad that one of his few great changes of heart(s) has been undone: his turn to vegetarianism.
In a way, it makes sense for the Doctor to be vegetarian. He's a telepathic alien who can apparently communicate with non-human creatures — in one recent episode, he can speak dinosaur — and he doesn't seem to draw a clear distinction between humans and other forms of life. And at the end of the horrifying/campy episode "The Two Doctors," the Sixth Doctor reflects on his encounter with a psychotic alien butcher who wants to eat human flesh, and decides that he'll just be vegetarian from now on.
How long does this decision stick? A fair while. The Sixth Doctor makes a big deal out of eating nut cutlets a few stories later. I'm pretty sure Sylvester McCoy's Doctor never eats meat, either. But when the show came back in 2005, this piece of character development had been conveniently forgotten — I'm pretty sure the Eccleston Doctor eats a steak at one point, and Matt Smith's Doctor of course eats fish fingers.
So my question is, what changed? Why did the Doctor decide at some point that he was okay with eating dead animals again? The obvious answer is, he went through the horrors of the Time War and decided he just didn't care any more. Or maybe, decades passed and he just got a craving.
As someone who eats meat myself — with some guilt about it — I'm not condemning the Doctor's choice, as such. I just think it's kind of weird, when you think about it, that he made such a big moral stand and then reversed course. Especially in the context of some episodes I've seen lately, where the Doctor seems to look down on human cruelty.
So what do you think changed? And when?