i THINK (and im taking a guess myself) that it means you're in the 100's in your weight. As opposed to being over 200

Onederland is when you get to the 199 mark.. you're no longer 200+.. so your weight is One something something.. it's often a milestone because it feels so good to get rid of that 2!

Yep...when your weight starts with a "one", you're in Onederland!

It means you are out of the 200's and into the 100's. If you hear century club that means you've lost 100 pounds! Great job on the weight loss!