This type of protein is a fast absorbing protein that aids in muscle tissue repair. Muscles grow by training the muscles this then breaks the fibres (hence muscle aches and soreness)and using a protien such as whey aids is speedier repair, the body repairs by replacing the broken fibres with more than there previously, hence muscles grow. should really be taken prior and post training for best results. Casein protein is a more slowly absorbed protein that should be taken at night to constantly feed the muscles throughout the night.

The amount of whey protein that you need to consume depends on your weight and diet. Whey protein supplements are taken in addition to your food. Your protein requirement needs to be arrived at considering your current weight and workout intensity.

Be sure to get in some sort of protein in the 30-45 minutes immediately following a training session. Even if it is milk or chicken, the protein is best absorbed in this window and will help you to recover and build muscle. If you are not looking into putting on weight but still want strength gains, keep the reps low (3-8) and make sure to keep doing cardio as well as cross training interval work (sprints, etc which will build power and strength while not adding excessive mass).