How much you eat isn’t a matter of willpower or lack of it. It’s an inborn, powerful biological drive to assure human survival. Trying to override the system with diet and food restriction is counterproductive because it triggers the body’s chemicals to turn on your appetite and increase hunger. Every time you under-eat or deny your body’s need for food, you actually crank into high gear a complex system of chemical reactions that tells you to eat. A vicious cycle? You bet.

You may think that your hunger alarm is all in your stomach and that dieting is all in your head. But the truth is that hunger is regulated by a complex system of chemicals that communicate with all the systems of the body. Signals are sent back and forth from your brain to your body. What starts hunger depends on whether the signals come from sensory or mechanical origins.

Scientists have identified that a specific area in the brain, the hypothalamus, is responsible for processing eating behavior. The cells in the hypothalamus communicate with cells in other parts of the brain to coordinate the release and uptake of chemicals forming the feedback system that helps regulate how much and what you eat. The chemicals that the body releases help the brain cells communicate with cells in the other parts of the body.

What starts the chemical chain? Food can be the trigger that stimulates the brain to turn the desire to eat into the actual act of eating. How a food smells, what it looks like, how you remember it tasting – in short, its sensory appeal – excites chemicals within the brain. Another way the process starts is at a cellular level, when messages sent to the brain tell it that fuel is needed and that it’s time to eat.

When the body needs nourishment, neurotransmitters (chemicals that transmit information to the neurons or brain cells) are released. Although more research is needed to help explain the exact mechanisms, one neurotransmitter called Neuropeptides (NPY’s) is thought to respond when the body needs carbohydrates. According to the theory, low levels of glycogen (carbohydrate in storage form in your body) and low blood sugar levels stimulate NPY’s release from the hypothalamus. As NPY levels increase, so does your desire for sweet and starchy foods. While you sleep, your glycogen and blood sugar stores are used up, and they send a message to the brain to release NPY. It’s no coincidence that our favorite morning foods are rich in carbohydrates – cereal, breads, bagels, and fruit. Skipping breakfast increases NPY levels so that by afternoon, you’re set up for a carbohydrate binge. This craving for carbs is not the result of a lack of will-power; it’s an innate biological urge at work. Stress and dieting are thought to trigger NPY production as well.