Dietary supplements in general, and protein supplements in particular, are a great way to make up the gap between the nutrients you get from dietary sources and the nutrients you need to accomplish your goals. For the great majority of people, dietary supplements will be limited to a single multi-vitamin a day; studies show that most people simply take supplements to feel better about themselves, rather than for any specific need. But those using protein supplements are generally power-users, who have very clear and defined goals as to what they need, and what they need to do to get there. The temptation to over-supplement is great; the immutable wall of diminishing returns, however, is soon reached when dealing with protein supplements.
The amount of protein supplementation you need will depend greatly on your level of activity and intensity of training as well as your ultimate goals. Endurance athletes, such as swimmers, cyclists and runners will need 1.2 to 1.4 grams of proteins per kilogram of weight per day, while bodybuilders will need 1.4 to 1.8 grams of proteins per kilogram per day. Bodybuilders who are training to increase their mass and bulk rather than maintaining what they already have will need up to twice that – up to 3.6 grams. The body, however, has a limited absorption capacity for protein, and anything over that will not be used and will be literally wasted.
It is thought that excess protein consumption can lead to kidney damage, as well as complications with the liver; these two organs act as filters for our body and need to break down and eliminate any excess, unused nutrients we consume. It is also surmised that over-consumption of protein supplements can lead, in the long term, to osteoporosis, although this has not been proven. Athletes and bodybuilders who need protein supplementation to avoid unbalanced and unhealthy diets should closely keep track of their protein intake so that it is in the 'sweet spot', so to speak; not too much, and not too little.
Bodybuilders and athletes should consider getting about half their protein from their diet, and half from supplements; the dietary protein constituents the baseline, while the supplement is taken as closely as possible in time to the actual workout, in order to promote cell growth and avoid protein catabolism. Keeping track of your protein intake will allow you to know exactly how much protein you need, and when you should take it to maximize your results. In general, follow the instructions that come with your protein supplements, and always use common sense.