The problem with your thinking is that you assume that your eating habits don't effect your energy consumption. But that is wrong, if your Blood Sugar is to high your Body can't access Fat and needs to Burn other sources that are scarce and it prefers to make you tired and cold to reduce energy consumption. That doesn't happen if your Blood Sugar is very low and you can easily access your Fat reserves. Eating spikes your Blood Glucose, that's why intermittend fasting works so great.
