If you are successful at pumping, yes. It's the milk production that burns calories. HOWEVER, not all women are successful at pumping (exclusively, I'm assuming?). It's HARD work and some just can't physically do it, their body doesn't respond to the pump... some just can't keep up with the labor involved in pumping AND caring for an infant.
Nursing will ALWAYS produce more milk because baby is more effective at stimulating milk production and it's just plain easier. After you get past the rough weeks in the beginning you don't have to think very much about it. This will give better results in the weight loss department (if you're one that loses weight, I am, personally... )... not to mention the obvious benefits to the baby of getting as much of your milk as possible, also many of the benefits of nursing involve direct feeding.
I know your baby is young... head over to breastfeeding moms for advice and support.
at 7:48 PM on Jan. 14, 2011