1) Fat enough to disgust shallow people.
2) Fat enough to make doctors presume that you eat mass quantities of junk food and never exercise--and therefore, prescribe weight loss as a cure for literally anything that ails you.
3) Having a body mass index over 30, regardless of actual body composition.
"Did you know that according to modern medicine, Joe is considered obese?"
"*Snicker.* Tell me exactly how Joe--Mr. Amateur Powerlifter, who's got a *tiny* beer gut--counts as 'obese.'"
"He's 6'4" and weighs 250#. That's all that counts to them."