Fat Adaptation

How can I tell if I am fat-adapted? I’ve been tracking my food for a while now. I typically eat a low carb diet. Since the start of June I’ve been eating about 50% fat; 30% protein; 20% carbs. I’m currently eating in roughly a 10 hour window. I also noticed a real lack of energy today; unlike the 1st 3 days of the program. Thanks!