Question

Is there loss of energy in total internal reflection?

Answer 1

No.

See When an incedent light gets partly refracted and reflected there is some loss of energy to the refracted medium but in case of TIR there is no such loss

Example :Light on slab gets refracted and reflected then if incident was having intensity I then relflected could have I/3 and Refracted 2I/3 Depending on the refractive index of the medium