I have read that the Buddha remained agnostic about the self. What anatta means, and I think this is very important, is that none of the five aggregates are self. I tend to take Thanissaro Bhikkhu's view on this that he gives in "No-self or Not-self?": http://www.accesstoinsight.org/lib/auth ... self2.html
He also has an essay with more detail called "The Not-self Strategy": http://www.accesstoinsight.org/lib/auth ... tself.html
I remember him saying in a dhamma talk that, like any other strategy, not-self must be used at the proper time. If not-self makes you want to not sustain your body with nourishment, then you may be applying not-self at the wrong time. The appropriate attitude in that situation might be metta; if anything we tend to not give ourselves the love we need.
The short answer to why I think we should care about our own nourishment: We can't develop the qualities of the path without support from our bodies, and the fruit of the path, nibbana, is what we wish for all beings, including ourselves.