Growing up, my parents enforced the idea that breakfast is the most important meal of the day.  One reason for that is that it is difficult to perform tasks, both physical and mental, without sufficient energy—which can come in the form of food.  Even now, I have difficulty being productive if I have not had enough breakfast.
But regardless of breakfast, the human brain, still one of the more intriguing organs in the body for scientists to explore, may have reached a stalemate.  Scientific theory has long differed when it came to the matter of how much of the brain we actually use. Now, some studies indicate that there is a limit to brain power and human intelligence has hit its peak.
These conclusions come from recent studies analyzing how much energy the brain requires to function. According to the results of some neurobiologists, any further brain growth would require too much energy. Does this mean that no matter how much food I consume, I won’t be able to handle high-level activities? Even if I listen to my parents and eat a good breakfast in the morning, could it be that I still won’t be able to perform higher-level activities?
Neurological processes, just as any other processes in the body, require energy to work. The brain has many different types of processes, which each require varying amounts of energy. The more complicated a task, the more energy required to perform it. For example, one may feel slightly fatigued after taking a simple subject quiz during school. Only one set of skills is being tested here. However, one may feel exhausted after taking a more complicated exam, such as the SAT or ACT. Not only is this type longer, it is testing more than one type of skill over multiple subjects.
Even within this idea of brain energy, there are differing viewpoints on exactly why our brains would need such a vast amount of it.
The brain can be thought of as a human computer, constantly sending messages and signals through wiring. This wiring connects to the whole body via neurons that send and receive signals. For example, if one touches a hot iron, the neurons in that hand send a message to the brain for the hand to pull away.
Some studies have shown that more intelligent people owe their success to their brain wiring. We’ve all run into the problem of a slow-functioning computer. Brain wiring is similar; the better the wiring, the faster the messages are carried. This has led to the conclusion that faster processing leads to greater intelligence. Consider language: if one’s wiring is able to process more, it is likely that one can learn a language quicker, and be able to process and understand multiple languages.
However, according to this idea, being “more intelligent” means one’s brain is consuming greater amounts of energy. Faster signals come at a cost.  It is just like exercise; walking only burns a small amount of calories, but running burns a much greater amount.  Based on this model, to dramatically increase brain function, for instance, the speed of wiring signals, would require greater amounts of energy and oxygen than we can produce. Our bodies would simply not be able to handle a “bigger brain.”
But the jury is still out on the brain: contrary to neurobiologists’s expectations, perhaps we will be able to evolve with bigger brains in the future. But, based on the projected amount of energy needed to handle a larger brain, this might require other evolutionary changes.  Along with a larger “dome” and speedier wiring, we may develop physical changes in the other parts of our bodies.  Maybe the size of the lungs will increase to contribute a greater amount of oxygen.
However, scientists still aren’t sure we are using our brains to fullest capacity.  Perhaps maximizing the gray matter we already have will prove to be a more successful alternative.