The main part of your brain that plays a central role in body reaction after not eating is the hypothalamus. The hypothalamus is located just above the brain stem and is responsible for regulating homeostasis, or balance, in your body. Food is necessary for body function, which means that when you're not consuming calories, the hypothalamus works overtime to restore balance to the body through the process of hunger.
When the researchers kept the participants’ glucose levels near normal, their brains showed more activity in the prefrontal cortex, the area that governs executive functions such as logic, reasoning and planning; this is the region that helps control emotions and impulses, like craving high-calorie junk food.
But when glucose levels were dropped, a deeper area of the brain, which includes the hypothalamus, thalamus and nucleus accumbens, started to light up instead. These areas are related to our emotional or limbic system, and play a key role in motivation, reward and addiction.
This happens because it’s an important survival strategy: when glucose levels wane, it’s a signal that the body is running low on fuel necessary to survive; the response is to remove any barriers to eating. Making food — especially high-calorie goodies rich with glucose — look good is a quick and powerful way to replenish those dwindling reserves.
Hunger is a distraction we’ve all had. Many studies show the negative effects that hunger has on school-aged children and young adults. Hunger is tied directly to low blood sugar which quickly leads to fatigue and low energy levels — and all wreak havoc on your ability to focus.
“Factors That Affect Focus and Concentration - Better Mind.” Bettermind, www.bettermind.com/articles/factors-that-affect-focus-and-concentration/.
“How Does Not Eating Affect the Brain?” LIVESTRONG.COM, Leaf Group, 26 June 2015, www.livestrong.com/article/482050-how-does-not-eating-affect-the-brain/.
Park, Alice. “The Hungry Brain: Why Food Looks Tastier on an Empty Stomach | TIME.com.” Time, Time, healthland.time.com/2011/09/20/the-hungry-brain-why-food-looks-tastier-on-an-empty-stomach/.