Finding an old growth/size difference story

I’ve been trying to find this old size difference/growth story on and off for some time now with no luck.

Here’s what I remember:

  • A nerd was crushing on the protagonist in high school. The protagonist tells him that he only likes bigger or muscular guys.
  • This leads the nerd to agree to some kind of experimental medical treatment that makes him into a giant. He ends up playing on some kind of football team, either for the eight/nine-feet tall giants or just as the biggest player on a normal team.
  • The protagonist runs into him years later, playing for that football team. They fall in love.
  • The story is in several parts.

I think it was moderately popular, because I can remember seeing fan art for it once upon a time, but I just can’t find it. Does anyone know what I’m talking about? It might have been here, but could have been elsewhere, too.