Wednesday, January 14, 2009

What Triggers Hunger?

By Susan Blair

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.

While you might think that it is your stomach telling you you are hungry the fact of the matter is that your hunger pangs are really triggered by a chemical process that begins in your brain and sends signals through your body. These signals then trigger feelings of hunger and can be generated from mechanical or sensory inputs.

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 we are sleeping our glycogen and blood sugar levels drop sending signals to our brains to produce more Neuropeptides. This is why cereals, fruits and breads are some of our favorite breakfast foods as they are full of complex carbohydrates.

If you skip breakfast your Neuropeptides increase so that as the day progresses you are ready for a carb binge and you overeat. This craving is not something that we can control with willpower, rather it is an innate biological urge that we must follow. Other factors such as dieting and stress are thought to trigger the production of Neuropeptides too. - 16463

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