For now, my personal workaround for this is to go back at the end of the week and delete weights on days where I know I did not have a weigh-in. If I do that every week (and don’t re-Analyze activities), my weight data stays ‘clean’. 
I did that, but I think there are occasions where HealtFit fills the gaps, for instance when I have installed the app on a new phone and pushed a new sync.
