Torturing the elements situated in the body, and Me also situated within the body, know them as of demoniacal determination.

Consequence of false tapas. Karṣayantaḥ — torturing, weakening. The object: śarīra-sthaṃ bhūta-grāmam — the aggregate of elements (bhūta) situated in the body — the deha-dhātus (bodily elements).

Also māṃ antaḥ-śarīra-stham — Me situated within the body. This is the Puruṣottama as paramātman. Conclusion: they are of āsura-niścaya — demoniacal determination/conviction. Body-destructive asceticism is asura, not divine.