but I thought that proteins= the muscles!! I just cant see myself eating chicken and fish and beef 10 times a day.. and that would end up more expensive than the shakes...
Anything worth having is worth the price you pay for it.
In my opinion, your system can only process so much protein. Don't overdo it. One rule of thumb is to ingest 1 gram of protein for each pound of bodyweight per day. So a 200 lb person would ingest 200 grams of protein a day. This includes all protein, not just what you get from the shakes. One reason many folks eat a lot of chicken or fish is because they are high in protein. Check the label on a can of tuna. The protein content is pretty high and tuna is relatively cheap.
Check labels on all the foods you eat, you'll be surprised how much protein there is in foods you don't normally think of as having protein in them. I drink a lot of dairy, eat cheese and eggs all good sources for protein.