Gluten is as Kryptonite.

Public Domain

Public Domain

If I were a super human and I had one weakness or Kryptonite as it were, I would have to say it is Gluten, nothing stops me faster than getting into gluten.

Feed me gluten and I will spend a lot of time in the rest room and unable to perform my super tasks.  Even at places where they have gluten free menus and kitchens they will still mess up.

To be a Superhero

I am torn on what super powers I would want to have.  I am not sure if I want Super Intelligence, or if I want to be a true shape changer (want to be a wolf, go for it.  Feeling fat today, Lose the weight.)