Well, it seems that eating balanced and healthy diet is quite important when you feel DP, because sometimes your body does not recognize its needs, at least that's what I figured out about myself. It is ok to eat less, just regularly, perhaps multiple small meals throughout the day.
People's experiences with alcohol in DP seem to be very different. One glass of wine is ok for me, it does not make me more or less DP. However, I tend to feel worse with intake of sugar, and alcohol contains sugar, so I kind of avoid both industrial sugar and alcohol. I understand what you say, though...I did feel that way when acutely DP, as if alcohol at least gave me reason for feeling so differently, and it did cover that numbness. It is just a temporary relief, however. And a lot of it cannot be good for you.