Does Anyone Know the Science of Stalls?

I am curious if anyone knows the science/biology of how stalls work from a physiological standpoint. This is really more just idle curiosity than anything but it got be wondering how our amazing bodies work in a weight loss phase.

I am 19 weeks out and have lost 89 lbs since my 10 day pre-op diet. There is a consistent pattern of 0 loss for 2-4 days then a loss off 1-2 lbs. not including the first 2 weeks I average a pretty consistent 2-3 lbs a week. Last week I only lost .6 lbs which was a first. Then in 2 days I have lost 3 lbs.

I have no complaints or worries but this does make me curious about what my body is doing while it’s processing this stored fat.

Any science geeks out there have any insight into how this works ?