You: On a Diet plus Collins GEM Calorie Counter Set

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Chapter 2

Can’t Get No Satisfaction

The Science of Appetite

Diet Myths

Hunger is primarily dictated by what’s happening in your stomach.

The biggest battle in dieting involves willpower.

As long as a food is low-fat it’s not going to make you fat.

As much as an iPod bud in the ear, fat has become a regular part of our landscape. We see it everywhere. We see it tethered to a hunk of prime rib. We see it masquerading as a Nutter Butter. We see it crammed into evening gowns or cascading over belt buckles. We’ve seen paparazzi-haunted celebrities gain it and lose it, lose it and gain it. And, if we can bear a confidence-crushing six seconds of nudity in front of a mirror, most of us have seen our own share of flesh that droops, sags, or jiggles. So, reason would tell you that we should know as much about fat as we know about Angelina Jolie’s private life. But we don’t.

Sure, we know what it looks like, what it feels like, and that it can be as bad for our health as a steak knife lodged in our hand. But few of us really know how fat works biologically—how the Twinkie morphs from a wonderfully yellow spongy cake to the flab that conjoins our inner thighs, or how our skinny-as-a-straw friend can wolf down a meat-lover’s supreme while we feel bloated if we as much as sniff four carrots.

Starting in this chapter and continuing throughout the rest of part 2, we’ll show you the way that food travels—from the time your body wants you to eat it, to the time it exercises squatter’s rights on your hips, to the time you fry it into oblivion. The best place to start? With your appetite. Appetite really comes in two forms: physiological signals that make you hungry and emotional coaxes that lure you to food.

In this chapter, we’ll explore those physiological signals, because understanding and controlling your hunger and satiety signals will help you adopt a healthy eating plan. (We’ll explore the psychological and emotional aspects in part 3.) Once you know that those mechanisms have much more powerful control over how you eat than do your taste buds, then you can make the behavioral, attitudinal, and biological adjustments you need to live at your healthy weight.

Above all, there’s one sign that will clue you in to whether you’ve become an effective processor of food. It’s the sign that you, not a bag of gummy bears, are in control of your weight. It’s the sign that you, without having to work at it, have been promoted to captain of your waist management vessel. And it’s the sign that you’ve ultimately reprogrammed your biology so that your body uses food as a medicine to make you stay healthier so that you live long enough to see how Lost ends.

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 nerve 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.

That sign? Satisfaction.

As you change from always thinking about diet to never thinking about it, you will be reprogramming your body so that it’s not your eyes, tongue, or overzealous utensils that will guide you.

YOU-reka! Instead, it will be the chemicals in your brain and body.

By tuning in to your body’s signals, you’ll allow your anatomy to work the way it’s supposed to: so that you’ll never be famished, you’ll never pop a button at the table, and you’ll never bounce between hunger extremes. Instead, you’ll get a little hungry, you’ll eat, you’ll stop. Satisfied.

The Anatomy of Appetite

You’d think that the first place we’d start to talk about how appetite influences fat would be the spot that’s covered by an XXXXL shirt. But to understand appetite, you have to navigate farther north—to the place that may hold the least fat. In your brain, you’ll find the hypothalamus, a key command center for your body. Among the biological functions it controls are your temperature, your metabolism, and your sex drive. Located in the center of your brain, the hypothalamus (see Figure 2.1) also coordinates your behaviors that involve appetite—not just for food but also for thirst and even for sex. So while it may appear that call-to-duty signals come from your stomach growling or your loins tingling like a static shock, it’s actually your brain that’s sending out the signals that you crave either a quiche or a quickie. (At least one person we know helped curb an eating problem by having regular, monogamous, healthy sex. When the appetite function for sex was satisfied, the appetite function for food was diverted.)

FACTOID

As you get older, you have fewer leptin receptors in your hypothalamus-meaning that you have fewer satiety signals, which makes you more prone to gaining weight.

Hidden in your hypothalamus, you have a satiety center that regulates your appetite. It is controlled by two counterbalancing chemicals that are located side by side (see Figure 2.2).

The satiety chemicals led by CART (the C stands for cocaine and the A for amphetamine, since these drugs put this chemical into overdrive). CART stimulates the surrounding hypothalamus to increase metabolism, reduce appetite, and increase insulin to deliver energy to muscle cells rather than be stored as fat.

The eating chemicals driven by NPY (a protein called neuropeptide Y). NPY has the opposite effect on the hypothalamus; it decreases metabolism and increases appetite.

Think of these two command chemicals as any game or sport that involves offense and defense, like soccer, checkers, or even dating. The offense is always trying to make advances, trying to score points, and trying to attack, while the defense protects its territory.

Your eating chemicals play offense. They want as many points as possible, so they fire off those signals for your body to score: eat, eat, eat, calories, calories, calories, chimichanga, chimichanga, chimichanga. The biological message: Prevent starvation by eating. Meanwhile, your satiety chemicals play defense, like a goalkeeper, the back row of checkers, or a protective parent. They send the messages to your brain that you’re full, to shield you from steadily pumping bacon-wrapped scallops down your gullet. How do we know these centers work this way? For one, by looking at extremes and seeing what happens when the feeding system is turned completely on or off. When we study animal models, we see that if a rat’s eating center is destroyed, for instance, it forever forgets to eat. The resulting severe anorexia starves the body of all energy and nutrients so that it withers away to the approximate width of an envelope. In rats whose eating center is overstimulated, though, food is always on the radar screen. And those rats eat themselves to death—literally—by increasing their fat-induced diseases like diabetes, hypertension, and arthritis.

Figure 2.1 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.

Figure 2.2 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.

FACTOID

CART (cocaine-amphetamine-regulatory transcript for those scoring at home) is the reason why cocaine addicts don’t gain weight. Cocaine and amphetamine stimulate this chemical, giving you a double brain bat to help you control appetite and increase metabolism. It’s unclear whether CART will be the basis for effective weight-loss treatments, but researchers are studying the neurological effects these drugs have on appetite to see if they could lead to long-term pharmaceutical solutions to weight loss (without of course, the dangerous side effects of illicit drugs). Marijuana, by the way, has its own receptors that overwhelm leptin, which is one big reason why pot smokers get the munchies. It’s also an area that’s a promising new approach to weight-loss drugs. By figuring out how the drug turns off the gene that produces leptin, we’ll be able to figure out how to flick it on-to keep leptin (and thus satiety levels) high. The prototype drug has done great in trials and symbolizes a new generation of smart weight-loss medications that work hormonally.

In a perfect system, your offense and defense complement each other; you get the foods you need and stop when you’ve had enough. Unfortunately for everyone except elastic-waistband manufacturers, a lot of things can mess up those systems (many of which we’ll discuss in a moment). But these obstacles aren’t insurmountable. You can take comfort (and find motivation) in the fact that your body wants you to reach your goals. Your body doesn’t want to be bigger than it should be. Your body doesn’t want lots of excess fat. Take the case of rats made obese by force-feeding. When they’re allowed to eat freely, they go back to their control weight. They eat what they should eat, withoutthinking. Same goes for starving rats. When allowed to eat again, they don’t gorge. They naturally go back to their control weight. And we know from years and years of research that what rats do is a pretty fair indication of what humans will do under the same circumstances. (Humans, of course, will do what rats do when they’re motivated only by biology. A rat isn’t upset by stress at home or work, which is why controlling the emotional aspect of eating plays such a big role in effective waist management, as we’ll discuss in Part 3.)

YOU-reka! If you can allow your body and brain to subconsciously do the work of controlling your eating, you’ll naturally gravitate toward your ideal playing weight. You do it by developing a well-trained defense that naturally balances the offense. When you do, you’ll win the diet game every time, whether you have willpower or not. Though it may not always be the case in football or Scrabble, when you pit offense against defense in your body, the offense in your body typically attacks more aggressively. It’s simply easier to scoop up bean dip than it is to leave it for others.

The Hunger On and Off Switches

Duct tape over your mouth isn’t how your body regulates food intake. Your body does it naturally through the communication of substances controlled by your brain. Although there are many hunger- and obesity-related hormones waiting to be discovered, there’s enough evidence to suggest that two hormones have as much influence for dictating our hunger and satiety levels as a head coach does on offense and defense—hour to hour and year to year.

Lovin’ Leptin: The Hormone of Satisfaction

In sumo champions, a little extra fat can produce good results. But we also think that fat has an unfair knock against it. Fat is treated a little like an accused suspect; it sometimes gets a bum rap. Fat produces a chemical signal in your blood that tells you to stop eating. Left to its own devices, fat is self-regulating; the problem occurs when we override our internal monitoring system and continue to stuff ourselves long after we’re no longer hungry. Your body knows when it’s had enough, and it prevents you from wanting any more food on top of that. How does fat curb appetite? Through one of the most important chemicals in the weight-reduction process: leptin, a protein secreted by stored fat. In fact, if leptin is working the way it should, it gives you a double whammy in the fight against fat. The stimulation of leptin (the word comes from the Greek word for “thin”) shuts off your hunger and stimulates you to burn more calories—by stimulating CART.

FACTOID

Neuropeptide Y is a stress hormone that increases with severe or prolonged stress. This may be why some people in chronically stressful situations tend to gain weight. Testosterone, the male sex hormone, seems to stimulate NPY secretion, while the female sex hormone, estrogen, seems to have a varying effect depending on the stage of a woman’s cycle.

But our bodies aren’t always perfect, and leptin doesn’t always work the way it’s supposed to. In some research, when leptin was given to mice, their appetites decreased, as expected. When it was given to people, they initially got thin, but then something strange happened: They overcame the surge of leptin and stopped losing weight. This indicates that our bodies have the ability to override leptin’s message that our tank is full. How? When leptin tells your defense—the satiety chemicals—to kick in and protect you against stray bonbons, the pleasure center in your brain says, “Uh, yeah, three more this-a-way” That surge from the pleasure center, which we’ll discuss in more detail in part 3, can overrule leptin’s messages that you’re full. That’s called leptin resistance (there’s another form of leptin resistance as well, which happens when cells stop accepting leptin’s messages). Most obese people, by the way, have high leptin levels; it’s just that their bodies have the second form of leptin resistance—they don’t receive and respond to leptin signals.

That doesn’t mean leptin is always on the losing end of this chemical battle. YOU-reka! The challenge is to let leptin do its job so that the brain demands less food. One way to do it: Walk thirty minutes a day and build a little muscle (that’s part of our activity plan in part 4). When you lose some weight, your cells become more sensitive and responsive to leptin.

FACTOID

Scientists found how ghrelin works accidentally: in gastric bypass surgery, doctors cut out the part of the stomach that secretes ghrelin. They soon realized that it wasn’t just the smaller stomach but the reduced ghrelin production that helped surgery patients eat less food. The eat-everything signal was shut off, clearing the way for the satiety center to take care of its business.

Ghrelin Is the Gremlin: The Hormone of Hunger

Your stomach and intestines do more than hold food and produce Richter-worthy belches. When your stomach’s empty, they release a feisty little chemical called ghrelin. When your stomach’s growling, it’s this gremlin of a hormone that’s controlling your body’s offense; it sends desperate messages that you need more points, you need to score, you need to FedEx the chili dogs to the GI tract immediately. Ghrelin makes you want to eat—by stimulating NPY. YOU-reka! To make things worse, when you diet through deprivation, the increased ghrelin secretion sends even more signals to eat, overriding your willpower and causing chemical reactions that give you little choice but to line your tongue with bits of beef jerky.

Ghrelin also promotes eating by increasing the secretion of growth hormone (ghre is the Indo-European root word for “growth”). So when you increase ghrelin levels, you stimulate that growth hormone to kick in, and growth hormone builds you not only up but out as well.

Your stomach secretes ghrelin in pulses every half hour, sending subtle chemical impulses to your brain—almost like subliminal biological messages (carrot cake, carrot cake, carrot cake). When you’re really hungry or dieting, those messages come fast—every twenty minutes or so—and they’re also amplified. So you get more signals and stronger signals that your body wants food. After long periods, your body can’t ignore those messages. That’s why sugar cookies usually trump willpower, and that’s why deprivation dieting can never work: YOU-reka! It’s impossible to fight the biology of your body. The chemical vicious cycle stops when you eat; when your stomach fills is when you reduce your ghrelin levels, thus reducing your appetite. So if you think your job is to resist biology, you’re going to lose that battle time after time. But if you can re-program your body so that you keep those ghrelin gremlins from making too much noise, then you’ve got a chance to keep your tank feeling like it’s always topped off.

Food Fight: The Ghrelin Versus Leptin Grudge Match

So now let’s get back to that offense and defense. The natural state is for you to have a give-and-take relationship between your eating and satiety chemicals—between your ghrelin and leptin levels—to influence NPY and CART, respectively. It’s the relationship between the impulse that says, “I’ll take a large pepperoni with extra cheese,” and the one that says, “No more passengers, this belly is full.”

This battle over eating isn’t between your willpower and the Belgian waffles; it’s between your brain chemicals. The NPY is the villain—encouraging you to buffets, driving you to the pantry, pointing its chemical finger to the convenience foods, while CART is your dietary guardian angel, which encourages a cascade of allies to keep you full and satisfied and in no way interested in creamed anything. Think of the two substances—NPY and CART—competing for the same parking space, the one that will ultimately determine whether or not you eat (see Figure 2.3). They both arrive at the same time and want that space. Either more NPY or more CART sneaks into the spot, thus sending the all-important go or stop signal to your brain to influence the hormones that make you feel full or hungry.

Here’s how they all work together: Ghrelin works in the short term, sending out those hunger signals twice an hour. Leptin, on the other hand, works in the long term, so if you can get your leptin levels high, you’ll have a greater ability to keep your hunger and appetite in check. Isn’t that great? Leptin can outrank ghrelin—to keep you from feeling like feasting on anything short of fingernails every few minutes. If you focus on ways to influence your leptin levels, and, more important, leptin effects (through leptin sensitivity), your brain (through CART) will help control your hunger.

Sometimes, it may seem like we don’t have much control over the chemical reactions taking place within our arteries or inside our brains. But just as you can control things like cholesterol and blood pressure by changing the foods you eat or altering your behaviors, you can also control the satiety center of your brain. How? Through your choice of foods.

Figure 2.3 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.

At least as far as your body is concerned, foods are drugs; they’re foreign substances that come in and switch around all those natural chemical processes going about their business within your body. When your body receives foods, different chemical reactions take place, and messages get sent throughout your system—turning on some things, turning off others. While your body internally gives orders, you set the tone and direction of those orders through the food you’re feeding it. Eat the right foods (like nuts), and your hormones will keep you feeling satisfied. But eat the wrong foods (like simple sugars), and you’ll cause your body to go haywire hormonally, and that ends up with one result: the next notch in your belt.

A major gang leader against your body is fructose, found in high-fructose corn syrup (HFCS), a sweetener in many processed foods. Here’s how it works: YOU-reka! When you eat calories from healthy sources, they turn off your desire to eat by inhibiting production of NPY or by producing more CART. But fructose in the HFCS, which sweetens our soft drinks and salad dressings, isn’t seen by your brain as a regular food.

Because your brain doesn’t see any of the fructose in the thousands of HFCS-containing foods as excess calories or as NPY suppressants, your body wants you to keep eating (which means that even low-fat foods can have extremely bad consequences, calorie- and appetite-wise). Americans have gone from eating no pounds of this stuff per person in 1960 to eating more than sixty-three pounds of it every year (that’s 128,000 calories). That’s a contributor to weight gain, since the fructose in HFCS doesn’t turn off your hunger signals. Foods with fructose—which may in fact be labeled as low-fat—make you both hungry and unable to shut off your appetite. They are also rich sources of calories: the perfect storm of weight gain. So you constantly get the signal that you’re hungry, even after you’ve jammed your gut with two baskets of calorie-laden, fructose-loaded biscuits.

YOU TIPS!

Get Over Sticker Shock. You should read food labels as actively as you read the stock ticker or the horoscopes. Don’t eat foods that have any of the following listed as one of the first five ingredients:

Simple sugars

Enriched, bleached, or refined flour (this means it’s stripped of its nutrients)

HFCS (high-fructose corn syrup-a four-letter word).

Putting them into your body is like dunking your cell phone in a glass of water. It’ll cause your system to short out your hormones and send your body confusing messages about eating. Today’s yearly per capita consumption of sugar is 150 pounds, compared to 7.5 pounds consumed on average in the year 1700. That’s twenty times as much! When typical slightly overweight people eat sugar, they on average store 5 percent as ready energy to use later, metabolize 60 percent, and store a whopping 35 percent as fat that can be converted to energy later. Any guess as to where 50 percent of the sugar we consume comes from? HFCS in fat-free foods like salad dressings and regular soft drinks.

Choose Unsaturated over Saturated. Meals high in saturated fat (that’s one of the aging fats) produce lower levels of leptin than low-fat meals with the exact same calories. That indicates you can increase your satiety and decrease hunger levels by avoiding saturated fats found in such sources as high-fat meats (like sausage), baked goods, and whole-milk dairy products.

Don’t Confuse Thirst with Hunger. The reason some people eat is because their satiety centers are begging for attention. But sometimes, those appetite centers want things to quench thirst, not to fill the stomach. Thirst could be caused by hormones in the gut, or it could be a chemical response to eating; eating food increases the thickness of your blood, and your body senses the need to dilute it. A great way to counteract your hormonal reaction to food is to make sure that your response to thirst activation doesn’t contain unnecessary, empty calories-like the ones in soft drinks or alcohol. Your thirst center doesn’t care whether it’s getting zero-calorie water or a mega-calorie frap. YOU-reka! When you feel hungry, drink a glass or two of water first, to see if that’s really what your body wants.

Avoid the Alcohol Binge. For weight loss, avoid drinking excessive alcohol-not solely because of its own calories, but also because of the calories it inspires you to consume later. Alcohol lowers your inhibition, so you end up feeling like you can eat anything and everything you see. Limiting yourself to one alcoholic drink a day has a protective effect on your arteries but could still cost you pounds, since it inhibits leptin.

Watch Your Carbs. Eating a super-high-carb diet increases NPY, which makes you hungry, so you should ensure that less than 50 percent of your diet comes from carbohydrates. Make sure that most of your carbs are complex, such as whole grains and vegetables.

Stay-Va-Va-Va-Voom-Satisfied. In any waist management plan, you can stay satisfied. Not in the form of a dripping double cheeseburger but in the form of safe, healthy, monogamous sex. Sex and hunger are regulated through the brain chemical NPY. Some have observed that having healthy sex could help you control your food intake; by satisfying one appetite center, you seem to satisfy the other.

Manage Your Hormonal Surges. There will be times when you can’t always control your hormone levels; when ghrelin outslugs your leptin, and you feel hungrier than a lion on a bug-only diet. Develop a list of emergency foods to satisfy you when cravings get the best of you-things like V8 juice, a handful of nuts, pieces of fruit, cut-up vegetables, or even a little guacamole.