Intermittent Fasting

I have been fasting as an experiment. In addition to Brooke’s info, I have been reading studies on it. I don’t have any weight to lose (101lbs 5’1.5), but there are still health benefits. I’m so hungry that my last hour of fasting in the morning I notice my focus is not there. Is this because I have no extra body fat? I do drink black coffee and probably 32-40oz herbal tea in the morning. I have upped my calories consumed during my non-fasting times because I was dropping weight. I eat no flour/sugar. I even extended my window to an 8 hour eating. I’m getting around 1500 calories a day. Any ideas on what is happening biochemically in my body? Been doing this for 2 weeks so far. I ate very clean before but not completely without sugar/flour (dark chocolate covered almonds are my downfall). I plan on going a full month but man-I’m hungry-lol. Oh-also I typically ate every few hours before as I follow a plant based low calorie density diet. (I’ve added more fat-nuts, avocado, seeds, etc) Would love to hear Brooke’s take on this. TIA!