Your body has built in low fuel lights, they come in various forms....a growling stomach, a feeling of low blood sugar and yes a feeling of exhaustion can be added to the list.....BUT..... you are new to this eating plan and a feeling of being tired can also be associated with sugar detox and changes occurring in your body. Generally speaking a true feeling of hunger will include more than one "fuel light" at the same time and most always stomach growing will be present.
The truth of the matter is you know when you're hungry and when you're not...that's why I have u go through the three day exercise at he beginning of the program. This way you'll get to know the signals. The rule stands...."Only eat when you are truly hungry". With that said, if you're not hungry in the morning, don't eat. If your first feeding time comes at noon and 2 meals a day is enough stick with it. Personally I never eat before 11 or 12 and in most cases I only eat twice a day, a brunch and a dinner.
Over the last three days you say you've been extremely tired, here's a couple of questions for you;
1- when you do eat at noon does the tired feeling disappear and stay gone for several hours? If so this may be a sign that your body was in need of fuel earlier than noon.
2- simple question, but are you sleeping well? When I first started FTS I tossed and turned for weeks before I started sleeping solid.
Getting to know your own body is a big part of your new lifestyle change, embrace it and pay attention to the signals