Hi LJ
Our bodies do some funny and frustrating things at times....are you a gym regular? And how long have you been using intermittent fasting? What time period do you fast for?
I would test yourself after Greek yoghurt without having been to the gym to see what affect it has on you. It could just be that your body was responding to the exercise and the result was higher bg reading. Did you restest to make sure you didn't have something sweet on your finger or that it wasn't one of those random incorrect readings?
Go look up Jason Fung reversing t2 diabetes on YouTube. It will show you the theory of using fasting and low carb as a way to reduce bg.
The idea is that you force the body to reduce insulin production through fasting and that when you do eat, you eat foods that do not cause a rise in bg and therefore insulin is not needed. The research shows that after fasting for 12 hours, insulin starts to reduce. You can fast for longer periods and the result should be less insulin and lower bg but 18 hours is sufficient t to make a positive difference. I've done the 5:2 diet previously and fasted for 36 hours but it was tricky to start with so for me, I feel that an 18 hour fast is more sustainable for me. So I stop eating at 7pm and don't eat until 1pm the next day. I have coffee in the morning and water, then two LCHF meals that I know do not impact my bg.
One thing to note is that protein can raise bg and this is where the fat part is vital as fat had no impact on bg. If you eat too much protein, it will convert to glycogen and therefore raise bg.
I think you need to experiment and see what happens over a period of time. We are looking for trends over a period of time so please don't feel disheartened just yet.
Another thing I do is test before I eat then at one and two hours after to see bg levels. Once I know what foods do what, I plan my diet accordingly.
Hope this makes a bit of sense....stick with it. We developed our condition over years so it may take a while to see some results but the key is consistency xxx