Does pregnancy diet impact postpartum weight loss? The answer is obviously that the amount of fat you gain during pregnancy directly dictates the amount of weight you will want to lose after giving birth. Much of the weight any pregnant woman will put on will be her baby, the placenta (which is quite heavy!) and the baby's amniotic fluid. This weight, clearly, will be lost immediately upon birth. How much this is varies from woman to woman.
If you have started eating a lot more than you usually do because of pregnancy, or your diet is higher in fat than it should be, you will certainly gain weight that can't be accounted for by your baby and it's habitat alone. A little bit of extra body fat is not a bad idea, certainly if you are planning to breastfeed. Breastfeeding burns around 200 to 500 calories a day, and your small reserve will be used up quickly.
"Eating for two" during pregnancy is, of course, a myth. You don't require double the amount of calories you do when you are not pregnant, just because you are growing a baby. Eating a varied and healthy diet that is not too rich in fatty foods, processed foods, and junk foods is indeed the ticket to an easier postpartum recovery. Eating right will promote your health and your baby's, and it may give you more energy during labor and delivery as well.