Most people can tolerate heavy amounts of fast food and artificial sweeteners. But some people like me are more susceptible to psychosis due to that stuff. Weed, fast food, other rec drugs and artificial sweeteners are the leading causes.
For me weed never caused psychosis.
My psychosis was however most likely because I was eating foods I was sensitive to.
For example, I was suffering from sweaty palms and feet since I was a little child, which is considered an incurable issue.
Once I cut out meat, gluten and dairy, among other foods like bananas and rice (Eating only certain fruits, vegetables, certain legumes and fish), my hands and entire body is completely dry, and it's been going like this ever since I cleaned my diet.
Also, my anxiety levels dropped significantly, I always used to be stressful in certain situations easily, and now I don't.
My whole body was stressed because of the way I was eating, and my psychosis always was triggered by immense anxiety.
So like I said, what we put in our body plays a major role in how we feel and also behave, don't underestimate it.
Peace.