This makes little sense until you look at the other things you cannot do: drugs, suicide, unapproved medical procedures, working for an unapproved wage, working at all without turning most of the proceeds over to the state, the list goes on and on. The conclusion is clear: we are slaves to the state. We cannot engage in behavior which might damage our bodies, because we do not own our bodies. They are owned by the state.
But I seem to recall that back in the days before slavery became universal, that a slave could buy his freedom from his master. Which leads us back to the thesis. I cannot sell my body. But can I buy it?