I've realized there is a lot of confusion regarding good health when nursing a baby. The information I've gathered is based on what I've experienced, and what I've read on websites like BabyCenter.com, eHow.com, FamilyEducation.com, and iVillage.com.
A common misconception is that you can't exercise while nursing because you'll "lose" your milk, or "dry up." I'm here to tell you from personal experience THAT AIN'T HAPPENIN'.
I found myself teaching fitness classes 6 weeks post-partum after receiving the okay from my doctor. I didn't teach at 100% because, let's be honest, my lady parts still needed some TLC. So I taught classes at my own level, and encouraged participants to do what they needed in order to feel challenged. I also did a lot of walking right after my daughter was born. Now that I'm 7 months post-partum, I'm still nursing, and I'm teaching at least 4 classes each week on top of my own personal exercise. I never once experienced a loss of milk because I ATE AND DRANK TO MY HEART'S CONTENT.
I can't stress that part enough. You must eat and you must drink like it's going out of style when you're nursing. There is absolutely nothing wrong with eating non-stop, especially if it's good food. Just avoid empty calories; go for filling snacks like apples with nut butter, or tuna fish mixed with tasty mustard on a piece of toast with avocado. Greek yogurt with your favorite fruit and honey. Find what fills you up and enjoy it. And drink water like it's going out of style.
If anything, working out was helpful to my nursing schedule. Since I sometimes missed a feeding, it gave me a chance to pump the milk that was building up so it could be used later. As long as you stay hydrated and well-fed, exercising will not adversely affect your milk supply.
An average nursing woman will burn 500 calories each day. That amount will differ based on your nursing routine. It's safe to say that if your baby nurses for 30 minutes at a time, each time, you're probably burning more than 500 calories per day.
Numbers don't really matter though. If you're hungry, eat. You do the same for your baby, right? I haven't paid attention to calories since my daughter was born. I eat when I'm hungry and I exercise 5 days a week. I'm back to my pre-pregnancy weight and shape, and I have a lot of energy.
The point is, find what works. Do what feels good for your body and for your baby. If it means you track calories coming in and being burned, so be it. If it means you eat willy-nilly and don't exercise for a while, so be it. If it means you find a happy medium, so be it.