The book you have in your hands is a manual for those who regularly conduct training in the gym or other sports. In this book we provide some useful tips on proper use of sports supplements such as creatine, L-carnitine, Whey protein, Omega 3, testosterone, caseina, glutamine, among others. More natural substitutes for each supplement are also proposed. All content exposed here has been corroborated by reliable bibliographical sources and reviewed by experts and specialists in the field. In the pages of this book the reader will find exact recommendations on how to consume each supplement during, before or after training or completing the corresponding cycles of supplementation depending on the finality of his activity in the gym ( bodybuilding or fitness). Here it is not intended to belittle the need for a proper diet, but rather attempts to explain how to supplement the deficits of the daily diet with supplementation of natural origin. For these reasons I speak in this book about the major mistakes that athletes make during sports supplementation. For more information about the content of the book we recommend to consult the index on the final page.