How much protein should teenagers eat?

According to the Encyclopedia of Healing Foods (Murray & Pizzorino, 2005), the U.S. RDA for protein in females is based on age. By the age of 18 the RDA is 44 grams; 19-24 years, 46 grams; 25+ years, 50 grams. Pregnant women should get 60 grams per day; lactating mothers should get 65 grams/day for the first six months and 62 grams/day for the second six months.

60+ grams of protein per day is not enough for a lactating woman. According to an article published in American Fitness in the mid 90's, you can multiply body weight by 0.4 and that will give the amount of protein needed for a sedentary adult per day. This is the same ratio recommended by many body building communities as a low to moderate protein intake, from which to start calculating additional protein needs. If a woman of say 5'5" weighing 130 lbs is lactating, she already needs 52 grams of protein for herself, and that is if she is sedentary. If she's making several cups of milk per day that's one gram of protein extra per ounce of milk, or probably around 30 or so grams of protein per day. If she is not sedentary, or is larger than my example, or is making more milk she will need even more protein. A lactating adult woman, who is not sedentary, would probably be well advised to expect to consume around 80-90 grams of protein per day if she wishes to remain entirely healthy.