The Sugar Smart Diet: Stop Cravings and Lose Weight While Still Enjoying the Sweets You Love (9 page)

But eat brownies or other sugar-laden treats too often, and over time the brain adapts to the surges in dopamine by producing less of it or reducing the number of dopamine receptors in the reward circuit. With the impact of dopamine reduced, you need more of the substance to achieve the same dopamine high.

This effect, called tolerance, occurs with street drugs. And it may occur with sugar, too. Research shows that sugar triggers the release of opioids and dopamine, as addictive drugs do, and more lab studies on rodents suggest evidence of sugar addiction. The parallels are stunning.

• Rats
  given daily access to sugar in the form of a sugar solution, only to have it taken away, will binge when it’s given back to them.
  
• When sugar is taken away, their teeth chatter, they develop tremors and the shakes, and, when put into mazes, demonstrate anxiety—all signs of withdrawal.
  
• After 2 weeks of abstinence from sugar—imposed by the researchers—they begin to seek and crave it, as demonstrated by repeatedly pressing a lever to self-administer it. (Luckily, you’re a lot smarter than a rat, and can actually learn to protect your health and short-circuit your sugar cravings.)
  

As it turns out, these findings have implications for humans.

Say that you’re “addicted” to chocolate (or jelly beans or chips—insert your must-have carb of choice here) and somewhere, a registered dietitian sighs. Nutrition experts have spent considerable time and energy saying that there are no bad foods. And they’re right, providing you don’t eat so much of them that they threaten your health, make you feel terrible about yourself, or otherwise hurt your quality of life.

But what if you
do
consume sugar to excess and can’t stop, no matter how much you want to? Is it possible for humans to be literally addicted to sugar?

There’s no simple answer. As the rodent studies discussed above suggest, a pattern of avoiding sugar and then bingeing on it can lead to behavior and neurochemical changes that resemble the effects of substance abuse. And researchers have long known that sugar affects the same feel-good brain hormones, dopamine and opioids, as street drugs.

Jokes about your daily sugar fix aside, there’s evidence to suggest that some people may abuse sugar. Take, for example, a 2008 study conducted on 61 overweight women, all self-reported carb cravers. The carbs these women craved weren’t in apples or quinoa, but in chocolate, gummy bears, chips, pasta, bread, pretzels—foods that are high in easy-digested carbs and/or sugar.

The researchers didn’t take the women’s claims of carb-craving at face value. To participate in the study, the women had to meet a list of stringent criteria. To name just a few, they had to report eating carb-rich snacks with a specific ratio of carbs to protein between meals at least four times a week, in the afternoon or evening, and that they either felt blue before eating them or felt their low mood lift when eating them.

The researchers wanted to know about carb-rich foods’ “abuse potential”—a phrase that refers to a drug used in nonmedical situations, repeatedly or sporadically, for its positive effects, including sedation, euphoria, and mood changes. Drugs with abuse potential can produce psychological or physical dependence and may lead to addiction
.

The findings, published in the journal
Psychopharmacology
, are interesting. Given a choice between a carb-rich drink and a protein-rich one, and with no information about what the two beverages contained, the majority of these carb cravers preferred the carb-rich beverage. But here’s where it gets
really
interesting. The responses of the women who
consistently
preferred the carb-y beverage indicated a key criterion of substance dependence: tolerance.

The study was broken into two 3-day sessions that occurred over 2 weeks. For the first 2 days of each “exposure” session, researchers asked the women to recall and focus on a sad memory as they listened to a piece of classical music shown in previous studies to invoke a melancholy mood. (For the record, it was
Russia Under the Mongolian Yoke
, by Sergei Prokofiev.)

Once they’d lowered their moods, the women were given either the carb drink (100 percent carbohydrate, from a variety of refined sugars) or the protein drink (37 percent whey protein, 0 percent fat, and 63 percent carbohydrates from refined sugars and food starch). Each volunteer was given one of the beverages in a red-topped cup on one day and the other beverage in a blue-topped cup on the other day; the same drink appeared in the same cup color across both weeks. The third day of each session was the test session: After again self-inducing a bad, sad, or low mood, the women were asked to choose and drink the beverage that had most lifted their moods. By a significant margin, the women reported better moods when they drank the carbohydrate drink.

Even more noteworthy: In the women who consistently preferred the carb drink, their liking for it grew over time, whereas the drink’s ability to lift their negative mood decreased over time. This suggests tolerance—the need for more of a substance to get the same effect, or when the same amount produces less of a “rush” with continued use.

The study’s conclusion? Sugary, starchy foods
do
show abuse potential, but only in those who crave them. In other words, it’s possible to develop a dependence on these foods’ ability to alter your mood.

Maybe you don’t feel that you’re addicted to sugar, have an intense emotional relationship with chocolate, or turn to food when life gets hard. In fact, you might think you’re eating just great. You’re microwaving oatmeal for breakfast and packing Greek yogurt for lunch and eating diet entrées for dinner, plus forking up salads with that amazing low-fat Asian ginger salad dressing. But the jeans ain’t getting any looser. You’re eating healthy food. What’s going on?

The incredible truth is that even if you avoid Straight-Up Sugar, there’s a good chance you’re consuming Secret Sugar—every day, and more than is healthy. The foods it’s added to would shock you.

But you don’t know that. You just wonder why you’re hungry, starving, famished all the damn time.

Recent studies suggest that chronic sugar intake messes with our brain’s ability to tell us to stop eating. Basically, eating too much added sugar allows the fructose in white sugar and HFCS to send your hunger hormones—the ones that tell your brain you’re full—into a tailspin.

Here’s what’s supposed to happen. Your stomach produces a hormone called ghrelin. That’s your brain’s cue to send out the “chow down” signal. As you eat, your stomach begins the process of digestion, breaking down your meal or snack and converting it to glucose, which enters your bloodstream.

In response to that influx of blood sugar, your pancreas releases the hormone insulin. Insulin in turn triggers your fat cells to send out a third hormone, leptin, which decreases your appetite. Basically, rising leptin lets your
brain know that you’ve had enough, thank you very much, and you can put the fork down and step away from the table.

Here’s where things can go right or wrong.

If your cells are sensitive to the effects of insulin, your body uses glucose properly, ghrelin and leptin stay in balance, and you are unlikely to overeat. But if your cells resist insulin’s effects—which is likely if you’re carrying extra pounds or have type 2 diabetes—your appetite doesn’t diminish and glucose is more likely to be stored as fat.

In addition, research suggests that consuming large amounts of fructose can wreak havoc on these hormones of metabolism. That’s because leptin, insulin, and ghrelin do not respond to fructose as they do to glucose, so your body doesn’t know when it’s had enough to eat. Without those internal controls—and
with
a steady diet of fructose foods—you’re liable to gain weight. The worst part: The fructose in these foods is often hidden, so you may not even know you’re consuming it.

In an ad campaign for a popular energy bar, elite athletes waxed philosophic about the beauty of competition. These dudes and chicks are
warriors
. What’s in that 2.3-ounce bar—sold in every drugstore, supermarket, and big-box store—that delivers such energy, such endurance?

Twenty grams of sugar, according to the Nutrition Facts label. The first ingredients listed: organic evaporated cane juice syrup, maltodextrin, fructose, and dextrose. That’s three sugars and a starch (maltodextrin)!

Athletes engaged in high-intensity competition can use the bar’s quick burst of energy. For those of us who tear it open and call it breakfast or lunch, not so much.

Food manufacturers often describe their sugary wares as offering quick energy. It’s quick, all right. Sugar can raise levels of the mood-boosting neurotransmitter serotonin in much the same way as a nutritious, fiber-filled bowl of steel-cut oatmeal. But that sugar rush soon evaporates, and your energy and
mood deflate like one of those holiday lawn ornaments on a timer. Your timer: 30 minutes or less, the time it takes from sugar rush to sugar crash. Sugary pick-me-ups can set you up for fatigue, low moods, and more unhealthy eating.

Let’s say you grab a sugary energy bar or coffee drink or a food that acts like sugar in the body—a package of cheese crackers or a big bag of pretzels. Their refined carbs are digested quickly and speed into the bloodstream as glucose. This rapid breakdown triggers a flood of insulin to transport that glucose into the cells. Shortly thereafter, blood sugar levels nose-dive, you get hungry, you reach for another pick-me-up, and the cycle continues. Sugar also triggers the release of serotonin—which regulates sleep as well as mood—causing postsugar drowsiness. You may crave more sweets to regain that sugar high or brighten your mood.

Sugar’s link to full-on clinical depression is complex. One theory about depression holds that it’s caused by a deficiency of brain serotonin. Antidepressants such as Wellbutrin and Prozac increase this serotonin. So does eating carbohydrates. People with serotonin-deficient brains may well medicate with carbs, especially sugary carbs. But over time, it takes more and more sugar to achieve the same boost in brain serotonin. Sounds like a great way to pack on the pounds, no?

So in the long run, sugar does not stabilize mood. It’s an unreliable friend—it drains you and leaves you feeling worse after your encounter rather than better. This was shown in a study published in
Public Health Journal
. A group of Spanish researchers examined the relationship between the incidence of depression and eating sugary sweets and fast food in 8,964 people. The researchers collected data on other variables that could influence the relationship between eating habits and depression, including age and sex, BMI and physical activity level, and total calorie intake and healthy food consumption.

After following the group for 6 years and adjusting for the variables noted above, the researchers determined that those who ate the most junk food had a 37 percent greater risk of developing depression compared to those who consumed the least.

And here’s another way sugar betrays you. What if a major part of the brain’s reward region reacted to the consumption of sugar in an abnormal way:
by not offering much of a reaction at all? This brain glitch may have its roots in yet another glitch, one of metabolism: insulin resistance, which is associated with an increased risk of type 2 diabetes. Scientists compared the brains of people with insulin resistance to those of insulin-sensitive people (whose cells absorb glucose efficiently). They found that, in people with insulin resistance, the nucleus accumbens (NA) released significantly lower levels of dopamine, compared to people whose cells responded normally to insulin’s effects.

The bottom line? The overeating and weight gain that often precedes type 2 diabetes might be related to these abnormally lower levels of dopamine release.

In the study, presented at a 2013 annual meeting of the Society of Nuclear Medicine and Molecular Imaging, researchers had two groups of people consume sugar (a glucose drink). One group was insulin resistant. The other group was sensitive to insulin’s effects. On a separate day, both groups drank an artificially sweetened beverage.

After both groups consumed each drink, the scientists scanned their brains to compare the release of dopamine in the NA. The results were then matched with the answers to a questionnaire that asked the volunteers to document their eating behaviors, so the scientists could catch anything abnormal.

After drinking the artificially sweetened beverage, dopamine receptors in the brain worked normally in both groups, the scientists found. Not so with the sugary drink. Compared to the insulin-resistant group, the NA of the insulin-sensitive group released significantly more dopamine. The brains of the insulin-resistant volunteers did not receive the same reward.

The bottom line: If you’re insulin-resistant, your brain may not reward you when you eat sugar by releasing normal amounts of dopamine. In other words, you may not be getting that sugar rush you want so badly. Trying to get that pleasure, you eat more, gain weight, increase your risk of diabetes, and feed that sugar belly.

If you suspect your love of sugar is messing with your mood, job one is to steady your insulin and blood sugar levels. Big spikes and dips can zoom you to the bright mood and energetic buzz of a sugar high, followed soon after by a crash that leaves you moody and tired. The Sugar Smart Diet can help get those blood sugar levels rock-steady. It can also help put you in touch with what
sugar means to you, what it does for you, and how to make healthy changes in the amount and type of sugars you choose to eat.

You can do this. We’ll do it together. The next chapter gives you an overview of the Sugar Smart Diet Rules. Read them now, and tomorrow you can take that first step toward sugar freedom. It might be a little rocky at first, but we’ll stick with you every step of the way, offering words of support and practical ways to make it through. Sooner than you think, your jeans will be looser; your energy higher; and your mood brighter. And in just 32 days, you’ll have kicked sugar overload to the curb, given food manufacturers a run for their money, and made your peace with sugar, reclaiming it as the pleasure it was always meant to be.