Participate in natural ingredient human study testing the safety of a muscle growth supplement. Study Purpose The study will evaluate over 90 days the safety of Celastrol, a natural compound extracted from the root of Tripterygium wilfordii, a herb used in Chinese medicine. Celastrol is being evaluated as a potential ingredient for a supplement to improve muscle growth (hypertrophy) with exercise. A total of 7 in-person visits paying $50 per visit, plus a $50 bonus for completing all visits for a total of $400. Eligibility Criteria - Individuals between 18 and 40 years of age - Women who are not pregnant or breast-feeding - Have not taken anabolic steroids in the last 6 months - No current history of alcohol abuse (MALE: More than 4 drinks/ day or More than 14/week; WOMEN: More than 3/day, or more than 7/week) - No current history of illegal drug use (marijuana is allowed) - Have not participated in clinical trial in the last 45 days