The main objective of this study is the considerations about the Effects of Leucine Supplementation. Leucine is a branched chain amino acids (BCAA), which is characterized by the ability to be formed from a conformation where an R grouping is non-polar aliphatic. It is noticeable a steady increase in the use of nutritional supplements among physically active, justifying the need of studies to verify the possible benefits and risks that they may lead to health of individuals. In this aspect, this study aimed to highlight the main biochemical and functional characteristics of Leucine. In addition to analyze the possible effects of its supplementation in diets for weight loss on physical performance as well as its benefits to human health, with the largest number of studies that addressed the issue, both in humans and in animals. According to the bibliography found, the Leucine supplementation can influence the protein synthesis, thus contributing to the anabolism, in addition to having an important role in regulating glucose homeostasis aiding weight loss process. Leucine appears as an important supplement for health benefits as an adjunct in the treatment of insulin resistance and may assist in gaining muscle mass in the elderly, as well as contributing to recovery from injuries and wounds in the muscle tissue. It is still necessary more research into the potential health benefits in view that many of the articles analyzed were conducted in animals. It is noteworthy that most of the research conducted tests on animals, highlighting the importance of greater academic literature on this topic. Besides, most relevant studies to conclusions about the effect of intake of leucine in physical performance are also needed, as there are still many disagreements over the results of leucine supplementation on this aspect.