I think it takes a few tries for it to really take root, so don't feel discouraged. Maybe you can start by giving up your favourite kind of meat for awhile and going with something that is less satisfying carnally(!) but still provides the nutrition you feel you are lacking...
I guess as Buddhists, the really important thing is the mind state that accompanies the eating, so maybe if we start getting aware of the kind of greedy, ravenous mindstate that sometimes is there when we devour our favourite burger, etc, that can be a kind of awakening to wanting to moving away from living-to-eat towards eating-to-live! I remember a photo my wife snapped of me when I was biting into something yummy and it was pretty monstrous the way my eyes were!
Someone has already probably mentionned this, but if you use the heavy kind of tofu that is readily available in the West (ironically, not here in Japan) and use spices skillfully when frying it, you can get something that has the texture of meat, or close, and just as much protein (or enough protein.) Anyone who says tofu is bland doesn't know how to cook it skillfully!