More than half the calories in breast milk come from fat. There are 20 calories per oz.
http://www.modernstork.com/content/002478.shtml
What nutrients does my breast milk contain?
* Casein
The fancy word for the special protien found in human breast milk that helps to preven gastroenteritis, respiratory infections, otitis media, some cancers, juvenile diabetes, and allergic reactions.
* IronThere is the perfect amount of iron for baby in mother's breast milk. Although cow's milk and infant formula contains more iron that breast milk, the human milk iron is abosorbed more efficiently by the baby.
* Lactose
Mother's milk has a high concentration of lactose, which helps to absorb much-needed iron.
* Vitamin C
Also aids in the iron-absorption.
* DHA
Docosahexaenoic acid encourages brain development and stimulates vision.
* Lipase
This fatty acid found in human milk contributes to how baby digests and abosorbs fats.
* Lactase
Aids lactose absorption. Both the central nervous system and "intestinal flora" are boosted by the high contents of digestible lactose found in breast milk.
* Amylase
Contributes to the digestion of starches.