I feel as though I don't deserve to eat?

It's kind of hard to explain but almost every time I've had something to eat in the last two or three months I've been getting a really guilty feeling inside telling me that I don't deserve the food in front of me. I think it may have something to do with a deeper rooted feeling I've had for years that I'm worthless and only cause more harm to the world then good, and I would rather just give my food to starving children in Africa and let myself starve since they could probably make better use out of their lives then I will mine. Is feeling this way common/normal? Could it be a symptom of something like depression/anxiety disorder? I've got a lot of other problems making me think I probably have some kind of disorder, but that's for a different question... Sorry for wasting your time.