Guys, word of warning. Do not allow your BMI to pop up over 30. Even if it is crap science, the doctors will then become, as said in the first post, bloodhounds. They may send you for blood tests for thyroid, do sleep apnea testing, blood glucose testing, wearing heart halters for blood pressure, and whatever they may think is causing your BMI to be elevated. If you want several months off, go in, say your having trouble sleeping and have a BMI over 30. Let the testing begin. And if you have ever been under the microscope, believe me, things will be found.
This is getting like the Asian carriers. Oh, you will eventually be found "healthy" for a medical...but what fun the paperwork, going to this specialist, that facility, dealing with fleet, etc. If you can walk, talk, see the airplane from the crew bus, and hear a sonic boom, for the most part they will pass you so they don't have to pay the money. But prior to that...your life will be miserable. And of course, there is always the finding a ground job in flt. ops until you are passed. Just a word of warning from knowing several people fitting the above description. Keep that BMI below 30.