Hm. You probably pushed the diet too far.

I went down from 93kg to 78 and then from 90kg to 78. I didn't go for low carb or sugar, just ensured enough protein and overall calorie deficit. Right now I am just carefully float around 80 kg.

This, and moderate excercise (kettlebells, some weightlifting, walking) made things relatively easy as I just made sure I stayed in an overall deficit.

One more point: it's the running weight average matters, not daily measurements.