...or something like that. He's on a prison planet in a mining camp, and they don't feed them enough to have the energy to escape.
So he kills the dwarf because it takes the least amount of energy. Then he eats the dwarf's food and then kills the next easiest victim, eating his food as well.
Eventually he gets enough energy to escape.
It's a SF novel from the 70's or 80's. Someone relatively famous. The main character's name might be Jack.
The mining dust gets caked on their skin and won't come off - turning everything into a gray or brown. When he finally escapes, it's into the arms of someone he owes money to, or something similar. Main character is a major alpha male.