Werewolf dietary habits vary greatly from werewolf form to human form. Wolves as a whole are obligate carnivores, so a werewolf who is vegan/vegetarian in human form would actively seek out meat in wolf form.
Cannibalism is unintentional with most werewolves, but of course, there's always that outlier that has to screw everything up for everyone else. His name starts with F, ends in Enrir.
Purposely cannibalistic werewolves are rare already, but Fenrir is someone who was born a werewolf, cannibalism, accidental or otherwise, is unheard of among the non-bitten. It's more common for the bitten to become cannibals due to struggles with adjusting to their new wolf instincts that can linger long after the full moon.
His people-hunting habits are part of the reason why Fenrir is always on the move, and his diet is supplemented by any animal he can get his claws on. Deer, pigs, cows, horses, sheep, squirrels, ect. He prefers his meat raw, since born-wolves are able to digest raw meat without any problems. Contrary to what he may have you think, he can eat fruits and vegetables. Fenrir has one known food allergy, and that is chocolate, and that's not related to being a canine or anything, he just sucks that much that he doesn't deserve the joy of chocolate.
Twig's diet consists mainly of raw animal meat as well. (For all his faults, her father DOES know the harm human meat can pose, so he's never fed her any. Broken clocks, you know?) She isn't a stranger to cooked meat however, though she doesn't start eating cooked meat more until she starts attending school. She also eats a fair amount of fruits and vegetables, and occasionally snacks on things that shouldn't be eaten. No known food allergies.
As a young pup, she used to hunt mice, frogs and insects.
When she first starts eating cooked meat regularly, it does mess with her stomach for a while until she's adjusted to it. Most of the cooked meat she eats is barely cooked to begin with (the same amount of raw full-blooded humans are able to safely eat) so god help you if you give her anything that's well-done.