Protein is arguably the most important macronutrient in a bodybuilders diet. It takes a lot of protein to maintain, support and build muscle in the body.
Protein molecules are made up of smaller units called amino acids. Once a protein molecule is broken down into amino acids, they are transported to muscle cells through the bloodstream to be used as the building blocks for muscle tissue.
For bodybuilding purposes, the minimum amount of protein recommended is around 1 gram per pound of bodyweight. The maximum amount of protein intake recommended is debatable, but most agree on between 1.5 grams to 2grams per pound of bodyweight as the most amount of protein to consume on a daily basis. When carbohydrates and fats are lower (generally when cutting calories to lose weight) the higher end of protein intake is preferred, as your body will be forced to use more protein for energy, requiring the extra surplus.
The most common recommended forms of protein to intake are any lean meats like chicken breast, turkey, and fish. Other great forms of protein are eggs or egg whites, and Whey protein. All of these types of protein are great additions to the bodybuilders diet, and all have different digestion rates. Whey protein, for example is digested very rapidly, making it ideal for post workout consumption and protein synthesis.
Putting it all together:
There is a lot of different ideas and examples of the proper amounts and ratios of macronutrients to use for a specific goal. People can get different results from different things, and so the ratio that works for one may not be the most ideal for another.
Some of the more popular ratios would be 30/40/30 or 40/40/20 (%protein/%carbs/%fats) for a bulking diet that would have higher intakes of carbs and fats. For a cutting diet, it would be common to see a diet similar to 50/35/15 or even 60/30/20 having a higher protein content and lower amounts of carbs and fats.
So for example,
A 170 lb guy with an average metabolism looking to gain a pound a week with a 40/40/20 diet would look like this.
Maintenance cals: 170x15= 2550 maintenance calories
Total Calories needed: 2550+500 per day= 3050 calories
3050x40%= 1220 calories from protein (305 grams)
3050x40%= 1220 calories from carbs (305 grams)
3050x20%= 610 calories from fat (68 grams)
Another example of a 200 lb guy with average metabolism looking to lose a pound per week with a 60/30/20 ratio:
Maintenance calories: 200x15= 3000 maintenance calories
Total calories needed: 3000-500 per day= 2500 calories
2500x60%= 1500 calories from protein (375 grams)
2500x30%= 750 calories from carbs (188 grams)
2500x20%= 500 calories from fat (56 grams)
Now that you have the run down of calories, its time to MAKE THEM COUNT!!