I address the usefulness of thinking about a human right to subsistence within conceptions of human rights grounded in ordinary moral reasoning. I argue that that natural rights should be understood as rights in rem, with their dynamism constrained by the requirements of justification and their scope constrained by the distinction between perfect and imperfect duty. I then suggest that many of the most pressing demands which the moral significance of subsistence needs create are plausibly imperfect duties, and so cannot correlate to a natural right to subsistence. This restricts the helpfulness of a human right to subsistence in our reasoning about what we owe to others.