We tend to think of hunger as a purely physical thing. Hunger is an involuntary reaction of our body, a bunch of chemical signals our stomach sends to our brain that munchies are required. The protagonist of Kafka's story treats hunger as an art form, as a performance. Hunger isn't just physiological reaction to him; it stands for so much more. So what does it stand for?
While the physical effects of starvation are clear (he's getting all skinny, boney, and weak), the story suggests that the artist is far more starved for artistic glory: he wants to be the greatest hunger artist ever. Indeed, this desire for artistic perfection comes at the cost of his bodily needs. His desire for glory seems more of a necessity than food – which leads us to wonder what the other characters in the story hunger for.
Judging by the popularity of certain spectacles (the hunger artist's act, the circus, the animal menagerie), it seems that the general public needs to be entertained, perhaps more than anything else in the world. Tellingly, the story ends with the public mesmerized by the spectacle of life provided by the panther – they prefer to watch life, rather than live it themselves.