This is like self discipline would have to go further as "when there is time and place".
The body has a number of processes that are not consciously controlled. Like the heart or the blood flow.
Despite a device some things still happen.
But there is more. I already said it.
If everyone believes they should eat certain things, true or not, it will have certain effects. If it's ok, it's ok. If not it can mean as much as death or common illnesses.