Food and other cravings, and guarding the senses

1. How do I deal with food cravings or craving in general? According to the four efforts I should replace craving with the disadvantages. Can loving-kindness also work? I feel like concentrating on impermanence and on the disadvantages, in the midst of an emotion, works not as effective. I guess one needs to strengthen one's conviction in both? 2. I read the Buddha saying about guarding the senses -- but I doubt that the Buddha meant not looking, not hearing (etc) at things. While it can be advantageous, I think perceiving them differently is much more important. Can someone answer what "sense-guarding" means, or "not grasping at the beautiful", and how do I do it?