Supplements High School Athletes need to stay away from.

1. Pro-hormones can alter the course of puberty and can render the athlete sterile by disrupting the hypothalamic-pituitary-gonadal axis.  There has been countless people who did Pro-hormones in their teens who now cannot have kids and have to go on hormone replacement therapy. 

2. Pre Workout first they are loaded with caffeine and other stimulants. Caffeine over 400 mg an athlete looses a ton of salt which is very important for athletes health.  Also caffeine increases cortisol levels which is the stress hormone can cause the following: thin skin, susceptibility to bruising, high or increased blood pressure, susceptibility to infections, build-up of fat around the face, chest and abdomen, thinning of the limbs, osteoporosis (thinning of the bones) leading to bone fractures, particularly in the spine, fluid retention (oedema), and diabetes. 

3. Branch Chain Amino Acids there is studies out there that cancer oxidize BCAA into glucose and will do that while it waits for you to eat.  Also your body would rather convert BCAAs into glucose than using stored fat.  

4. Soy Protein is a cheep grain that is a GMO.  Also they use Soy in post menopausal women as a therapy because it is a phytoestrogens. Also lower your IGF-1 levels. It causes calcium loss which is very important to female athletes who can be prone to Osteoporosis.

Also if you compete and your governing body uses the World Anti-Doping Agency here is the list for 2019.

https://www.usada.org/wp-content/uploads/wada_2019_english_prohibited_list.pdf