I have a normal BP who goes off feed in the winter months. This past winter he fasted from 11/5/15 to 1/31/16, then refused feedings till 3/22.

On 11/05/15, he took a small f/t rat weighing 57g.
On 01/31/16, he took a small f/t rat weighing 62g.
On 3/22, he took a small f/t rat weighing 68g.
On 4/3 (4 days ago), he took another small f/t rat weighing 76g ...

Here is a record of clean weights during the period:

11/04/15 820g
11/05/15 - Took f/t Rat 57g as noted above)
11/11/15 835g
12/25/15 812g
(01/31/16 - Took f/t Rat 62g as noted above)
02/08/16 788g
02/21/16 764g
(Shed 03/07/16 - previous shed was 10/08/15)
03/14/16 747g
(03/22 - Took f/t Rat 68g as noted above)
03/28/16 798g
03/31/16 780g <------------
(04/02/16 - Took f/t Rat 76g as noted above)
04/06/16 822g
04/07/16 817g <-----------

Last year he went from 339g to 316g in a similar, but less marked weight fluctuation pattern (with similar feeding behavior) before shooting up in weight when back on regular feeding.

I'm wondering if this is due to his metabolism kicking back into gear, or if something else might be wrong. 18g lost in 4 days, and 5g lost in 1 day (<-----) seems unusual to me... Thoughts?