The Anatomy of Appetite

 When you feel hungry, it’s actually your brain that sends signals that you’re craving a quick bite, not your growling stomach.In the center of your brain, your hypothalamus coordinates your appetite behaviors (not just for food but also for thirst, sleep and sex!).Sometimes, when the appetite for sex is satisfied, the appetite function for food is diverted. This is one reason why inadequate sleep or sex can make you hungrier.QUIZ: Are You Getting Enough Sleep?Hidden in the hypothalamus, your satiety center regulates appetite. Two counterbalancing chemicals sit side by side, controlling the center:1. The satiety chemicals led by CART (the C stands for cocaine and the A, amphetamine, because these drugs put this chemical into overdrive). CART stimulates the hypothalamus to increase metabolism, reduce appetite and increase insulin to deliver energy to muscle cells (rather than store them as fat).2. NPY (a protein called neuropeptide Y) drives the eating chemicals. NPY has the opposite effect on the hypothalamus. It slows metabolism and increases appetite.Think of these two chemicals as any sport that involves offense and defense, like soccer, chess and even dating. The offense is always trying to make advances, while the defense protects its territory.The eating chemicals play offense. They fire off signals for your body to eat, calories, eat, chimichanga. The biological message? Prevent starvation by eating.At the same time, your satiety chemicals play defense, like a protective parent. They send messages to your brain that you’re full (shielding you from speed-eating those bacon-wrapped scallops at the dinner party).We know these centers work this way for a couple of reasons. First, we can look at the extremes, seeing what happens when the feeding system’s shut completely on or off. We see that if a rat’s eating center is destroyed, it permanently forgets to eat. The severe anorexia starves the body of all energy and nutrients so it withers away to the width of an envelope.In rats whose eating center is over-stimulated, food is always on the radar. Those rats eat themselves to death, by increasing fat-induced diseases like diabetes, arthritis and hypertension.A perfect system would have your offense and defense chemicals complement one another. You’d eat the foods you need, and stop when you’ve had enough.Unfortunately, sometimes those systems aren’t perfect. You can take comfort in the fact that your body does want you to reach your goals. If you can allow your body and brain to subconsciously do the work of controlling your eating, you’ll gravitate toward your ideal weight.MORE: Outsmart Your Eating Instincts

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