What is the direct thermodynamic necessity linking a sloth's diet to its famously slow movement?

Answer

Moving fast would require too many calories that the low-energy diet cannot easily supply.

The sloth's slowness is a direct necessity imposed by its diet; the leaves cannot easily replace the calories lost through unnecessary movement.

What is the direct thermodynamic necessity linking a sloth's diet to its famously slow movement?
dietanimalmammalherbivoreSloth