I buy my own juice all the time just so that I can drink out of the carton. If someone else wants some, I lay out the ground rules and inform them of what has occurred. Oftentimes, I have separate "guest-friendly" containers that have not touched my mouth. I will "waterfall" tea out of the pitcher, because I know my roommate also enjoys when I brew tea, and I'd rather not spill a pitcher on myself. I'll often go for a glass if I want more than a single drink.

I also have an entirely separate fridge in the game room solely for alcohol, though I don't see that as a bad thing.

I will impulse-eat because I forget that I haven't had meals or whatnot, and whatever the closest thing is that I'm not allergic to ends up being my next meal. Sometimes, when the pantry is nearing emptiness, that means going to the store and overfilling a shopping cart, or swinging by a drive-thru to avoid buying two weeks of groceries for a single late-night snack.

Don't shop while hungry.