Sorry I keep trickling in information. Cos I remember all this in haphazard fashion.
OK in the insulin window you should not be calorie deficient. Protein is a wash, cos most proteins cause enough insulin slow enough to just allow for their processing.
But carbs cause insulin out of proportion with their calorie load.
Fat causes lower insulin than its calorie load.
If you have insulin without the accompanying calories, you will have a lower metabolic rate.
If you have calories without insulin, your body will have to burn it and you therefore have a higher metabolic rate which then continues and rises when fasting.
In that concept I almost think eating carbs in the beginning of the meal makes more sense. Ideally as little carbs as possible.