Kind of, you need to keep an eye on your overall calorie intake, so if you eat 300+caloiies of whey protein (most packets will tell you to eat almost double that! But then they make their money selling you the next packet don't they).
Bodybuilders, and to a lesser extent all athletes work on a bulk and cut principal. Bodybuilders eat a caliroe surplous (with lots of protein) and do lots of weights for a period of time, anywhere between a week and several years, this builds up muscle ('bulk'). They then have to spend an equal ammount of time doing less weights, more cardio and eating a calorie deficit to 'cut' the fat off.
Cyclists do the same proces through the winter, you ride long rides to build up endurance, then diet in the spring to get the improved power/weight ratio you were after.
Thats why I'm not loosing weight, I'm not really trying to, just building up the muscle first then I'll diet properly at the end of the summer, before doing a lot of training over the winter, then one last diet in the spring to get to where I want to be.