You actually can have too much protein. Unfortunately, the body does not store protein. Instead, it turns the protein to fat, and then stores the fat. When fat is stored, you become overweight, and that physique that you were shooting for will fly out of the window. This, however, is the least of your problems if you are taking in too much protein regularly.
An overdose of protein can lead to ketosis. Ketosis means that there are too many ketones in the blood stream. This, in turn, can cause damage to the kidneys. Dehydration is also a result of too much protein. So, as you can see, very serious health problems can occur when you take in too much protein, or too much of a protein supplement. The weight gain that you will experience will be the least of your problems.
So, how much protein do you need? How can you be sure that you aren't over doing it? As an athlete, you need .6 to .8 grams of protein for each pound of body weight. Many bodybuilders, however, take in about one gram of protein for each pound of body weight, and most do not have any problems with this. This is very common for strength trainers.
The protein that you take in can come directly from food, or from protein supplements, however, a combination of solid foods and liquid protein supplements is recommended. In the case of replacing food with protein supplements, you can also have too much of the protein supplement, regardless of how much or how little protein you are actually taking in.
You see, your body needs solids and liquids. It is true that liquid protein is easier for the body to absorb, which is why a liquid protein supplement is recommended immediately after working out. However, your body needs to go through the act of digesting food, and it works harder at digesting protein, which in turn burns more calories. Again, you need a combination of solid foods, and liquid protein supplements.
Again, bodybuilders do need more protein than sedentary people, and even more than some other types of athletes. However, remember the 'all things in moderation' rule, and understand that taking in more protein supplement than you actually need to reach your goals will not actually get you anywhere near your goals. Instead, it will leave you overweight, and in poor health.