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The brain

The brain acts as the central processing unit for all these various forces and influences. Different parts of the brain control responses to different stimuli.

Perhaps of greatest interest in a discussion of eating is the hypothalamus. This cluster of nerves, located near the front of the brain and surrounded by the hemispheres of “gray matter,” is astonishingly powerful given its tiny size. The hypothalamus, serving as a kind of gatekeeper between the brain and the rest of the body, coordinates many activities, including the central nervous system, the endocrine system, and the autonomic nervous system that governs, among other things, breathing and digestion.

The hypothalamus receives signals from the body about the state of energy supplies, decides what has to be done, and issues orders accordingly. For example, “hunger” signals sent from one part of the brain to other areas propel us toward the refrigerator. During the meal, various feedback loops change the concentration of certain brain chemicals. The hypothalamus records all of these changes and signals other parts of the brain to stop the eating. You put your fork down and push yourself away from the table. This is a “satiety” response. Without it we would continue eating to the point of physical pain.

Although small, the hypothalamus is divided into several discrete areas. Since the 1940s, we have known that damage to one area can disturb metabolism, resulting in overeating and obesity. Such results led to the early conclusion that the hypothalamus housed the central mechanisms in charge of hunger and satiety. We have since learned, however, that the eating process is much more complex than this simplistic explanation would allow. Hunger signals are now thought of as “decentralized,” traveling not just from the brain to the body, but from the body to the brain as well.

Research has also revealed that the hypothalamus, like the rest of the brain, is awash in a biochemical bath. The different areas of the hypothalamus are studded with specific receptors geared to respond only to certain neurotransmitters.

Other organs

The brain is just one of the links in the chain of the eating process. Other links include the nose, mouth, esophagus, the digestive tract, the bowels, and the kidneys.

Until recently, people tended to look on the stomach as just a passive bag that received food, broke it down, and passed it on. New discoveries indicate that the gastrointestinal system plays an active role in regulating the intake of food.

Food landing in the stomach sets in motion a series of events. The stomach and small intestine react to the size of the meal and the type of nutrients contained in the foods-fats, carbohydrates, and so on-by releasing the right mix of acids and other compounds necessary for digestion. Various gastrointestinal peptides are released in response to feeding, which in turn signal the hypothalamus to “terminate eating.” (A peptide is a compound of two or more amino acids; proteins are long sequences of amino acids linked together.)

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Comments (0) Apr 22 2009

Murray Hann admits that he wasn’t the kind of person that you’d expect to find on a tennis court. At 315 pounds, he looked more like a spectator than a player. “But I played a decent game, even as a fat guy,” he says.

His love of the sport helped him launch a regular fitness program—and helped him lose almost half of his body weight.

Murray, a 38-year-old mechanical engineer from Palm Bay, Florida, had a weight problem throughout his entire life. “I grew up with a wonderful, Aunt Bea type of mom who regularly baked cookies for my brother and me,” he recalls. “I ate more than I should have, and it showed.”

At age 30, Murray started feeling self-conscious about his size. “I didn’t want to spend the rest of my life alone, and I believed that that’s what would happen if I didn’t slim down,” he says. “There was no woman on Earth who was tolerant enough to see through all that fat.” ; ^

As much as he wanted to shed the extra pounds, Murray refused to go on a diet. “Diets provide only temporary results,” he ex- j <j§ plains. “I wanted to lose the weight permanently. I knew that that would mean making lifestyle changes.”

Murray thought about how much he enjoyed tennis, along with a number of other sports. He figured that he could stick with a regular exercise program, which in turn would help him lose weight.

“I made up my mind to work out every day, no matter what,” he says. “Sometimes, I felt selfish because I put exercise so high on my priority list. It became almost as important to me as food, water, and sleep.”

His brother gave him a rowing machine, which Murray used every night. “I wouldn’t fix dinner until I completed 40 minutes,” he says. He continued to play an occasional game of tennis. As his fitness improved, he graduated to racquetball, then mountain biking, then walking, then jogging, then running.

To support his new exercise habit, Murray began paying more attention to his food choices. He cut back on fat while making sure to get an adequate amount of protein.

With regular workouts and a better diet, Murray was able to take off 150 pounds in about a year. He has maintained his weight at 165 pounds since 1992.

Exercise had another, unexpected benefit that made Murray even happier than his trim physique. He met his wife, Susan, on the racquetball courts at a local recreation center. “We played against each other, and she kicked my butt,” he recalls.

S These days, Murray and Susan often work out together as part of their active lifestyle. In addition, during his lunch hour, Murray usually runs with a group of coworkers. “I enjoy the sunshine, fresh air, and camaraderie more than food,” he says.

WINNING ACTION

Do what you love; love what you do. There’s no rule saying that you have to walk or run or pedal a bike to lose weight. Anything that gets your body moving burns calories. So find an activity that you love. Murray is a great role model: He loves tennis, and he used it as a springboard to establishing a regular exercise program. The point is that if you enjoy what you’re doing, you’re more likely to do it.

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Comments (0) Apr 22 2009