What is the ruling on using protein powder extracted from eggs and milk and manufactured in America, knowing that it is free of forbidden ingredients and helps in building the body?

There is no harm in joining a bodybuilding club or practicing any sport that aids in it, with the intention of strengthening oneself for worship, provided that these activities and clubs are free from prohibitions such as intermingling and the exposure of prohibited 'awrah, and the use of prohibited substances like alcohol or anything made from dead animals, blood, and pork. One should refer to specialists to know the ingredients of substances and ensure they are free from prohibitions.