He would, under ordinary circumstances. The trouble is that he's a werewolf, stuck in vampire prison, and a prisoner of prisoners. I'm not actually sure they have such things as energy bars/drinks lying around. They have plenty of steak, because the vamps eat cow blood--but that doesn't always go down so well for him. Which is ironic, but there you have it.

Fortunately, it hasn't gotten too horrifically bad for him at this point in the story (horrible physical trauma is old hat to him; it's the mental ones he has trouble with), so I manage to get him to eat. In this case, it was just a matter of moving the part where she feeds him to earlier in the scene.