This is a controversial topic, and depending on who you ask you will see some wildly varying answers. On the low end you have the RDA, which for me would be about 68 grams of protein per day, and on the high end you have bodybuilders who would tell a guy like me to eat 380 or more grams per day.
So from 68 to 390 grams...that's a huge difference. Why is there such a big difference there?
Related Posts:
Whey Protein Benefits: https://www.youtube.com/watch?v=Z7Pe1Thodq4
3 Muscle-Building Tips: https://www.youtube.com/watch?v=c8CIulMoaKo
Blog post: http://strongerleaner.com/how-much-protein-to-build-muscle/
Video: https://www.youtube.com/watch?v=8mEQXXJZrc4&feature=youtu.be