I'm going to submit this as a recommendation too on the Garmin site, but I know they sometimes read here too. Why not simply allow the users to enter an automatic offset. For instance, if you have some other measurement you are more confident in, and the Index S2 is saying you are x% over that recording, you would calibrate as such.
I don't believe for one instant garmin's canned response that tells me how to weight myself and how their bioimpedance is accurate. It does not pass the logic test if you have a 6 pack and the thing tells you you are 23% body fat. Also, all of the users who have identified the problem...
The offset would at least allow you to keep the functionality of other great thing the scale does, such as the automatic wifi, but allow your history to not look like you gained 10% body fat at the time you bought a $150 scale to help you further refine your health.
