I prefer mine really rare...like, still in cow form.
I think anything in moderation can be perfectly fine on a diet. Either do a healthier swap (sorbet instead of ice cream, whole wheat for white, etc) just plain cut back(if you want those really decadent things(or burn it off, yay exercise), or make the smartest choice available(like leaner cuts of meat).
As long as you watch the typicals, like portion, calories, fat, sugar & sodium, make sure you're getting your water & veggies/fruit, & let yourself occasionally indulge in what it wants, you're good to go.
Everything in moderation & remember...your body is a temple, treat it like one!