The short story was about a man about to go on a space journey/colonize a planet and having to abide by an extremely strict weight limit. He talked about starving himself, shaving hair and doing everything possible to reduce his weight. The story says some people were doing this to bring diamonds or gold with them, but the main character is revealed to be doing it because he wants to carry a book with him because he thinks it's the most important thing.
I think the book he brought with him was Charlotte's Web.