I would like to know if it is a sin to practice bodybuilding, or if it is a sin to take proteins?
No, nowhere in the Bible it is written that it is sinful to practice this sport, or to take proteins that drive muscle growth. Anyway, this issue must be dealt.
I am an International Taekwon-Do instructor and I think that it is welcome to tell my point of view as a coach.
Based on the observed, I concluded that most those who resort to practicing bodybuilding are concerned with their appearance. This concern leads them to get more interested in the muscle volume than in the health of those muscles and of the body in general. Therefore, they begin to use in food proteins and various chemical components just in order to increase muscle volume. They do not care which may be other effects of these products although there are many cases when these products have caused health problems, because they affect metabolism more or less.
When you are sick and there are not enough certain elements in your body you will use medicines. But if you are healthy, and take those medicines in a certain amount, they will cause your disease. I think the same thing is available for this excessive surplus of proteins.
And then, in general, it is not good when people become more concerned about their outer than inner state. When addressing to women, regarding to this subject, the Bible says:
Your adornment must not be merely external–braiding the hair, and wearing gold jewelry, or putting on dresses; but let it be the hidden person of the heart, with the imperishable quality of a gentle and quiet spirit, which is precious in the sight of God. (1 Peter 3:3-4)(NASB)
If women are not befitting when they set a higher price on the external adornment than on the inner one, so much the more men are not befitting to be concerned excessively (not to say obsessed) with their external appearance.
Translated by Felicia Rotaru