Jack's dislike of Piggy is becoming more and more blatant. How do we see this when the boys are eating? How does it change your perception of Jack?
Piggy represents everything that Jack loathes. Piggy is weak and worthless. Piggy can't hunt or fight or build. Piggy's intellectual traits are lost on Jack. AS the story unfolds, Jack sees the opportunity to link Ralph with Piggy. Constant humiliation and derision of Piggy habituate the boys inflicting cruelty on Piggy and perhaps (in time) Ralph. The withholding of food to Piggy further marginalizes him from the rest of the boys. Jack isn't stupid. He is better at manipulating the boys than Ralph which, to many, is what politics is all about. Jack is truly evil but his intelligence makes him that much more scary!