It might sound strange at first: consuming fewer calories leading to a feeling of increased energy. But there is scientific evidence showing that a lower caloric intake optimizes the mitochondrial energy production. That increase in cellular energy efficiency is caused by two factors, which are known today. For once the heat that is a byproduct of ATP production is reduced through an altered gene expression and modulated enzymatic reaction. This is elaborated in detail in AIR Volume 1 by Dr. Amen-Ra.
Secondly regenerative and restorative processes known as autophagy are increased. On the one hand this saves energy through a lower amount of inactive and damaged cellular components that inhibit an efficient conversion of food energy to ATP. On the other hand this increases the life span of individual cells and their components and at the same time renewing them more efficiently with a higher recycling rate.
Through those two mechanism and probably more that have not yet been discovered, a lower energy intake can yield the same amount of cellular energy with less resources being utilized.
In my own experience this leads to a greatly increased feeling of energy and mental clarity. But it took a considerable time to adapt to a lowered caloric intake in order to feel these changes. But in combination with intermittent fasting and a high fat plant based diet, the human body can feel truly efficient and adequately fueled without the feeling of deprivation.
Even though the adaptation to a very short eating window (1-2h) is not easy, it has led to a great change in how I approach food and how much satisfaction I derive from it. While resisting all the food temptation during the fasting phase, takes some initial discipline, it slowly transforms into a feeling of superior fuel utilization. That is the utilization of stored body fat to fuel all energy-requirements in the most efficient way during the fasting period. After some time all tissues adjust with an adaptation on the cellular level. They increase enzymes to utilize fat as fuel and become less dependent on glucose as fuel. Even the brain can derive a large portion of its energetic needs from ketone bodies and can reduce its glucose demand to a minimum. I think this is what most noticeably increases the feeling of energy.