Henry Cavill for The Witcher:

This schedule culminated in complete water restriction on the final two days, including the day of shooting the shirtless scenes. Cavill explained that the goal was to make his skin “sit on the muscles” for optimal visual impact, a tactic commonly used by fitness models for photo shoots.

[...]

Describing the ordeal on The Graham Norton Show, Cavill admitted the experience was intense and taxing. “By the last day, I could smell water nearby,” he joked, emphasizing just how miserable he felt. The extreme dehydration was so draining he dubbed himself “the most miserable person on the planet.”