hippochondriac

A fat person possessing an excessive preoccupation with
personal health issues, with the exception of their own obesity.

First he's worried about having a sore throat. Then his heart
is beating too fast. Next he's worried that his headache
won't go away. Maybe the hippochondriac should stop
worrying about everything else, and start worrying about
weighing over 300 pounds.

Hippochondriac

Someone who has an irrational fear of losing at Hungry Hungry Hippos

Tom: I'm bored. You guys wanna play a board game or something. How about Hungry Hungry Hippos?
Sean: We can't. John's a Hippochondriac, he flipped the table the last time we played