Whey protein is an excellent supplement for anyone wishing to assure adequate protein intake. In fact, of all the protein sources (natural and supplemental) it has the highest biological value. This is a measure of how well it is absorbed by the body.
Whey protein is a by-product from the production of cheese. Since its source is milk/animal it is considered a complete protein, and can provide amino acids which the body can not produce.
Being a protein, whey is considerably low in fat and carbohydrates and ideal for low fat low carb diets. However, sometimes flavoring is added so check the label as this can increase carbohydrates present.
Protein consumption should make up approximately 15-20% of daily caloric intake. However, some experts will recommend a higher percentage, especially for someone that is trying to lose excess fat.
The recommended quantity of protein consumed is approximately 1.0 - 1.5 grams per kilograms of body weight. E.g. if you way 50kg you should be consuming between 50-75 grams of protein per day. However, if you are in your growing years, or exercise considerably, you should consume a bit more.
Some other excellent sources of protein include fish, chicken, eggs, milk, red meat (in moderation), and nuts.