YOU on a diet - Fat's Bad Rap

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Fat's Bad Rap Sure, nobody likes body fat, especially when it beats you through the door by five or six seconds. But despite potentially serious consequences, fat, by nature, is good. (That's not a typo.) Besides helping Santa hopefuls land December jobs, it also helps your cells function and provides insulation. Most of your fat is stored in a reservoir throughout your body. You have drums and drums of it, sitting passively, just waiting to be burned. But you have another kind of fat, too. It's called brown fat and is usually found on the back of your neck and around your arteries (and has absolutely nothing to do with how much chocolate you eat). This increases in outdoor workers during cold spells to protect them from the weather; it insulates our vital organs. Though you have a fairly small percentage of brown fat as an adult, about one-third of fat in babies is brown

fat, and it's used primarily to keep them warm. What makes brown fat different? YOU-reka! Brown fat is alive. It has verve fibers, like any organ, and it also has leptin receptors. When the level of this hormone goes up, it turns on energy consumption in the brown fat and burns it. This is important because it shows that the right leptin levels can signal you to immediately get rid of this fat. And it's also symbolic of the inherent goodness of body fat-when it's found in the Right amounts. Food Fight In your hypothalamus, you have hunger and satiety chemicals. The hormone leptin goes to the satiety center to make you feel full and satisfied, while the signal from the hormone ghrelin makes you want to eat, gorge, and slobber over your every feast. Chemical Reaction If we look closely at the hypothalamus, we see that a small nucleus at the bottom houses NPY and Cart, which fight the yin-yang battle to control the brain biochemistry of hunger. Each chemical readily travels to other nuclei in the hypothalamus. NPY causes our temperature to drop and our metabolism to

decrease as we feel hungry. CART stimulates the opposite influence. The nearby mammillary body (literally shaped like a nipple) is part of our limbic system, where we store memories and emotions - just the right combination to create a craving for a favorite food. The thalamus is the body's relay station and rapidly transmits orders throughout the brain based on the desires of the eating center. In a Jam The satiety center is waiting to be turned off by NPY or stimulated by Cart. Whichever fills up the

receptor docks first is what controls whether you want to eat more or not. In turn, these two proteins are influenced by lack of water, sleep, and even sex. They're also influenced by ghrelin coming from your stomach, which stimulates NPY so you get hungry, and leptin from your fat, which is further stimulated by a chemical called CCK, released from your intestines after a meal. Gutting It Out Food pulls over at various spots in the intestinal track, so disease of these areas can cause nutritional deficiencies even if two

people are eating the identical foods. Not all of the nutrients that come from food and supplements get absorbed in the same place; they're absorbed throughout your GI tract. Here are the rest stations where nutrients are absorbed: Stomach: alcohol Duodenum (first part of the small intestine; takes off from the stomach): calcium, magnesium, iron, fat-soluble vitamins A and D, glucose Jejunum (middle part of the small intestine): fat, sucrose, lactose, glucose, proteins, amino acids, fat-soluble vitamins A and D, water-soluble vitamins lie folic acid Ileum (last part of the small intestine, leads to large bowel): proteins, amino acids, water-soluble vitamins like folic

acid, vitamin B12 Colon (also known as the large bowel): Water, potassium, sodium chloride Taste Tester The most powerful muscle in the body, the tongue, tastes food with papillae that sense the chemicals in foods and tell you whether they're worth you continued attention. Chewing the Fat One of the reasons we can gain weight so readily is the efficiency of our teeth, which fit perfectly with one another to ensure that every morsel of food is crushed completely. Salivary glands near the lower teeth and at the back of mouth secrete enzymes to hasten digestion before swallowing. The sight and smell of food warn these systems of what's to come.