[Avodah] Is there an issur in smoking marijuana?

[Gershon Seif]

Rav Moshe Feinstein in Igros Moshe YD III:35 writes that it's forbidden for a few reasons. One of them I found interesting was that the smoker's parents wouldn't like it. (Nowadays that wouldn't be an issue.) Another reason he gives is because of being like a ben Sorer Umoreh who among his transgressions is being a glutton and also not caring about mitzvos. Rav Moshe writes that someone who is high arouses his desire for food and other pleasures and that is not a Torahdik way to behave - as well as being sloppy with his mitzvos in that state of mind. There are other reasons given there but I don't have the sefer in front of me.