To use fat reserves (lipolysis), two conditions must be met:

- Insulin must be absent
- fat must be eaten

Going into starvation means no fat is being eaten. One condition is not being met. BMR will slow down to maintain calories in-out balance to avoid losing precious fat reserves. Fat reserves will remain intact after calories from fat eaten run out. Gluconeogenesis will begin, protein stores will be used instead of fat stores. Especially since you need proteins for building blocks, repair and maintenance. You will shrink alright but not by lipolysis.

Coming out of starvation will take a while because BMR is so slow from it. You wrote you eat about 10% carbs. That's ample enough to prevent lipolysis. Especially since BMR is so slow. Insulin is present, no lipolysis can take place. One condition is not being met.