Clara H., what did you eat, and when, on fasting days? I find that I have to make sure I get plenty of protein and at least a little bit of fat each time I eat on a fasting day. If I eat a food that is primarily carbohydrate, even something healthy like an apple or some porridge, it just won’t hold me, I’ll be hungry in an hour or two. I usually save most of my calories for my evening meal, I can feel a bit tired the last couple of hours before eating that, but then I feel better and go to bed feeling better. Some people do better saving all their calories for their evening meal, they find that eating anything sets off the whole hungry/tired cycle. Try different strategies to find what works for you.