Boybuilding supplements are substances taken by athletes involved in weight training or other sports to aid in the building of lean muscle mass or to cause fat loss. Bodybuilding supplements may also be used to improve sports performance and improve recovery from events and training. One important distinction exists in many weight training groups between supplements and anabolic steroids. There is a common misconception among non-supplement-users that supplementation for muscle-building purposes is the same as steroid use or, at the very least, leads to steroid use. However, this charge is often challenged by supplement users on the grounds that supplements do not mean to change natural hormone levels (primarily those of testosterone) beyond natural limits, while anabolic steroids do.