CHAPTER FIVE
Appetite Control, What We’re Up Against
===========================================In order to develop a plan for appetite control, you need to learn as much as you can about the appetite, which is a complex system that involves the senses, chemical processes in the body, and the psychological makeup of the human mind. Also, all of our senses can play a part in activating our appetite in one way or another. The senses, taste, smell, sight, touch, and hearing can all be used to remind us that it’s time to eat.
Psychology or common sense is the reasoning that says we must eat regularly to live and remain healthy, but there is more to it than that. When the appetite is triggered, the body releases different chemicals into the stomach and brain to tell us when to eat and when to stop eating. Our need to eat, to stay alive along with our appetite, make it difficult to skip a meal knowing that our health and well being depends on good food.
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Then there is our metabolism, which is the process of using food for energy, growth, development, and maintenance over a lifetime. Trying to understand either appetite or metabolism is difficult at the least. However, trying to learn how they’re all associated with each other and how they interact is even more of a challenge.
Nevertheless, we are beginning to understand more and more of what’s happening through the science of appetite control and weight loss. New research is helping us understand the cause of excess weight gain and is helping us come up with ways to help turn it around. However, getting people motivated enough to try and stay on a new weight loss program is another challenge.
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By gathering and studying facts regarding the science of appetite, we can see bits and pieces of the picture gradually developing. We can use the facts to help us make assumptions, deductions, and educated guesses about appetite control and food choices. Also, the facts can help us formulate a plan for action for solving the problems we are facing. Let’s study one of the important facts about the appetite.
Since we know from research and experience that it takes about twenty minutes for the appetite to go away after the stomach is full, we can assume that people are programmed to overeat. We can also assume that at one time in the past, it was okay to overeat because of the programming. Now that food is plentiful, and we have evolved pass the stage where it is necessary to over eat, what can we do?
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Let’s start by studying the chemical reactions that make us hungry enough to overeat in the first place. In 1999 a hormone called ghrelin, which is often referred to as the hunger hormone because it causes hunger, was identified. The body releases ghrelin into the stomach each day during the times we normally eat our regular meals. This causes an empty feeling in the stomach, which lets us know it’s time to eat.
When ghrelin reaches the brain, it goes to three areas: the hindbrain, which controls the body's automatic, unconscious processes; the hypothalamus, which governs metabolism; and the mesolimbic reward center in the midbrain, where feelings of pleasure and satisfaction are processed. This powerful series of events guarantees that when ghrelin is released into the system, you will respond by eating something if food is available.
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As scientists continue to study ghrelin, they are finding out more about how it works in the body. They have found that the levels of ghrelin spike at mealtimes. The release of ghrelin into the stomach keeps pace with your feeding schedule. That’s why we get hungry three times a day whether our bodies need the food or not. Also, whenever there is a change in the mealtime pattern, there is a change in the times when ghrelin spikes in the stomach. Even without the spikes, there are low levels of ghrelin in our stomach at all times of the day, which accounts for our need to have two or three snacks in between meals.
Another chemical found in the stomach is called cholecystokinin or (CCK). It is a peptide that is released by the upper intestine. It then travels to the brain to give you a feeling of satisfaction so that you will stop eating when you get full. However, the effect of CCK is temporary. That is why you may get hungry after returning home from having an expensive meal at a nice restaurant.
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Even CCK is limited in its ability to prevent weight gain. CCK does no good if the person consumes a nutrient rich meal that consists of mostly fats and sugars in foods such as fried chicken, white rice, white bread, cookies, and milkshakes because a high calorie meal such as that can contain about 3,000 calories or more. Also, after the stomach gets full, it could be another twenty minutes before CCK is released into the intestine to signal that the stomach is full. If your stomach gets full before CCK reaches the brain, you may continue to eat. This causes the stomach to stretch, which allows the person to consume extra food.
Next in line are two other hormones to stop us from eating: GLP-1 and PYY. They are used to make sure you stop eating before you overeat. They are also produced in the stomach and travels to the brain. From the brain, they send out signals to let you know that you have had enough to eat. They also tell your stomach to stop processing food so that nothing else goes into the lower intestines. This gives the stomach time to digest and process some of the food you have eaten. Also, GLP-1 adjusts blood chemistry by stimulating the pancreas to release more insulin. The insulin helps to store all of the excess sugar into the body's fat cells. This process should regulate the amount of food you eat and help keep you healthy by eliminating sugar from the bloodstream. However, this system seems to eventually fail because of a heavy sugar overload.
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Another appetite-suppressing hormone was discovered in 1994, called leptin. It is supposed to cause people, who are overweight, to eat less. If it worked the way it should, fat people would eat less than skinny people. A person’s body fat produces this hormone, and it is usually produced in direct proportion to the amount of fat tissue the person has. The fatter you are, the more leptin your fat cells produce. Once in the bloodstream, it travels to the hypothalamus, which is one of the same regions of the brain targeted by ghrelin. When it reaches the hypothalamus, it muffles the signals caused by the ghrelin that stimulated the appetite in the first place.
The discovery of leptin caused excitement in the world of dieting. Researchers thought that obese people were simply suffering from a shortage of leptin in the body. It would be simple to supplement the hormone and watch the fat disappear, but that didn't happen. After years of research and testing, they found that only a few people had a deficiency in leptin production. They also found that the leptin systems in most overweight people works exactly as it is supposed to work. The hormone levels climb when the person’s weight goes up and falls when the person’s weight goes down.
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Somehow, this natural system of weight control has failed also. It seems that when some people reach the level of obesity, their bodies will not respond to supplemental leptin treatment. This appears to be especially true for people who have been overexposed to leptin. For some people, the leptin system works the way it should, for others it does not.
Also, researchers have found dozens of other hormones and peptides that are involved with appetite control. They are studying the new findings to see how the information can be used to help manage our eating habits and help us lose weight. In the meantime, we are getting bigger and bigger.
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