We need stakes and a way to verify starting and ending weight
Lack of stakes eliminates the need to verify starting and ending weight. Do it for bragging rights, but more than that, do it for yourself!
^^^This.
Besides, in order for it to be totally legit we would all have to weigh in on the same scale. Like DoA said, do it to get healthy! And bragging rights too!
Jesus... I hope you know Him personally like I do.