I am not seeing anything abnormal with those weights considering they are going through winter fast.
There is a lot to take in consideration not just the weight loss itself but the animal itself, the health of the animal, hydration.
The key is to monitor the animal (obviously you have been doing this) your husbandry and be patient.
Do I have animals that look skinny right now? Yes I do, some have stop eating, have loss weight and they appear leaner than usual, nothing I am worried about given they are healthy and hydrated.
One thing people need to remember is that their metabolism is VERY efficient.