Many supplements come in capsule form.

For other uses, see Dietary supplement.

Bodybuilding supplements are substances taken by athletes involved in weight training or other sports to aid in the building of muscle mass or aid 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.

Also, a distinction is sometimes drawn between dietary and exercise supplements, while this method of classification is not followed by all those who use supplements. If a distinction does exist, dietary supplements are often defined as those supplements that aim to give the body more of the nutrients that it ought to get from diet, but isn't for whatever reason. Protein, meal replacement and amino acids (in smaller quantities) based supplements are usually considered to be dietary supplements. Exercise supplements, however, involve raising a particular nutrient level far beyond what is typically consumed by a human for the explicit purpose of experiencing a positive side effect when combined with weight training. Creatine is a good example of an exercise supplement in that, while it is found in the body naturally, users typically ingest far more than is usually needed in order to saturate their muscles and achieve a much greater muscle gaining benefit.