Thomas Aquinas, Compendium of Theology

As we said above, in speaking of the saints, the beatitude of the soul will in some manner flow over to the body. In the same way the suffering of lost souls will flow over to their bodies. Yet we must observe that suffering does not exclude the good of nature from the body, any more than it does from the soul. Therefore the bodies of the damned will be complete in their kind, although they will not have those qualities that go with the glory of the blessed. That is, they will not be subtile and impassible; instead, they will remain in their grossness and capacity for suffering, and, indeed, these defects will be heightened in them. Nor will they be agile, but will be so sluggish as scarcely to be maneuverable by the soul. Lastly, they will not be radiant but will be ugly in their swarthiness, so that the blackness of the soul may be mirrored in the body, as is intimated in Isaias 13:8: "Their countenances shall be as faces burnt."