Running in Ketosis

August 19th, the day after my birthday, I started on a ketogenic diet. I had a 5k run the next day and was in ketosis after my run. Today the 24th, I still am feeling weak and have an elevated heart rate when running. I am only having coffee in the morning and then eat again about 2:00 pm. Then around 6:00 pm I have a small cup of Greek yogurt and a small piece of mozzarella cheese.