Hi, there! I do believe that you should eat at least your minimum calories for a number of reasons:
1. You could enter starvation mode, making it even harder to lose the weight (as discussed in the Spark Power link that Corina attached)
2. You could compromise the quality of your breastmilk, as it requires a base level of nutrients
3. You could wind up using up your body's own stores of nutrients (for example, calcium) which could compromise your own future health. If your body doesn't get what it needs from your diet, it will take whatever it needs from your stores, leaving not much for you.
4. As you become more active again and burn the excess fat, your body might start cannibalizing muscle. Muscle loss is something none of us need, especially as we age.
Anyway, just my two cents worth. Hope this helps.
~~ Leslie ~~