The National Research Council recommends that adult men and women ingest daily (on average) about 0.75 gm of protein for every kilogram of weight. A gram is about the weight of one lima bean. A kilogram is 2.2 pounds. A woman weighing 125 pounds should consume about 43 grams of protein per day. An ounce is about 28 grams. So, 2 ounces of a protein per day would meet that requirement.
However, not just any protein will do. These recommendations are fashioned around “reference proteins”. These reference proteins refer to “highly digestible, high-quality proteins such as egg, meat, milk or fish”. Proteins are made up of amino acids. Some amino acids are “essential” for humans…..these “essential amino acids” cannot be manufactured in our bodies, and must be consumed in our foods. The reference proteins contain all the essential amino acids. Can you get all the essential amino acids without eating the reference proteins, which are all animal-source foods……yes, but it takes some special effort (see Vegetarian Nutrition below).