Why does Jonas start to question his decision about leaving?

Near the end of Lois Lowry's novel The Giver, Jonas and the Giver make a plan for Jonas to leave the community and go Elsewhere. When his father announces that the toddler Gabriel is going to be released (meaning given a fatal injection), Jonas decides to leave earlier than planned so that he can take Gabriel with him and save his life. He steals his father's bike, with baby seat attached, and the two make their escape.
The two face many challenges, including hiding from search planes and Jonas twisting his ankle. However, what makes Jonas begin to doubt his decision to leave is when they start running out of food. He begins to think about the fact that nobody ever starves in the community and questions whether he made the right choice by leaving. Jonas comes to his senses when he remembers that if he were still in the community, he would be starved of love and emotion, and Gabriel would be dead.