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The Glycemic Load Diet
A POWERFUL NEW PROGRAM FOR LOSING WEIGHT AND REVERSING INSULIN RESISTANCE
By ROB THOMPSON
McGraw-Hill Copyright © 2012 Robert Thompson and Dana Carpender
All right reserved.
Chapter One Understanding Why You Gained Weight
It's enough to drive you crazy. You're constantly battling your weight while others seem to stay thin effortlessly. They don't exercise, they eat anything they want, but they don't get fat. The perplexing thing about the obesity epidemic—and this has been true of other scourges throughout history—is that some people are more vulnerable than others. They suffer from the harmful effects of our modern lifestyle, while others seem to be immune. Overeating and lack of exercise are not the whole story.
But for years, people thought that being overweight was a matter of choice. Just as some folks played golf or did crossword puzzles for enjoyment, others got their kicks from eating. Doctors knew of certain hormonal disturbances that could make people gain weight, but they thought these were unusual. Most overweight people just chose to be the way they were.
Of course, who in their right mind would choose to be fat? If it came to a decision between being overweight or getting hit by a truck, some people would probably opt for the truck. Almost everyone would agree: obesity is unattractive, cumbersome, and unhealthy.
Being overweight, then, suggested you were either weak-willed or had some kind of psychological problem. However, when psychologists got around to studying overweight people systematically, they came up empty-handed. It turns out that overweight people are psychologically no different from thin folks. They have some bad habits, but no more than anybody else. They get a little depressed, but who wouldn't be? One thing is certain: they aren't weak-willed. Obese people often show remarkable self-discipline in other aspects of their lives. After all, 65 percent of Americans are overweight. Do all of these people have some kind of character defect? Of course not.
It's Not a Matter of Willpower
Do you remember when you were a kid and you tried to see how long you could hold your breath? It was easy at first, but after a minute or so, you developed a different mind-set. Lack of oxygen triggered chemical reflexes that told you in no uncertain terms you needed to breathe. Certainly, the need for oxygen is more urgent than the need for food, but the principle is the same. If you reduce your caloric intake, changes in your body chemistry stimulate powerful hunger-driving reflexes that overrule lesser concerns like how good you look. When those instincts say "eat," unless you have unusual willpower, you eat. You can postpone it for a while—and you have some control over the kinds of foods you eat—but if you try to defy the urge, you usually come away the loser.
The reason self-deprivation rarely works for losing weight is that it defies deeply rooted survival instincts. Consider this: Your body burns about 1.2 million calories a year. If your weight depended on your consciously regulating the amount you eat, misjudging by 2 percent (that's about two bites of a potato a day) would add or take off forty-two pounds in ten years. Who can fine-tune their eating that much? Your body can't afford to rely on your whims. It has its own mechanisms for balancing calorie intake with energy output.
Just as a lack of willpower didn't make you gain weight, simply willing yourself to eat less is unlikely to result in lasting weight loss. You might think you can dial down your calorie consumption at will, and maybe you can for a while. But let's face it: if you're like most people, you'll eventually return to your old ways.
A Matter of Hormones
In recent years, scientists who study body chemistry have discovered several hormones that regulate body weight. Here are a few examples:
Your thyroid gland makes a hormone called thyroxin, which helps regulate how fast your body burns calories.
Your stomach secretes ghrelin to stimulate your appetite when your stomach is empty.
Your intestines produce peptide YY to curb your appetite when your intestine has enough food to work on.
Your fat cells secrete leptin to reduce your appetite when your fat stores have been replenished.
Those are only some of the hormones known to control weight, and scientists are still discovering new ones. The point is this: powerful chemical reflexes regulate the balance between the calories you take in and the rate you burn them off. Body weight is not simply a matter of choice.
The hormone systems that regulate body weight evolved over millions of years during times when hunger was a constant threat. Although these mechanisms helped keep fat accumulation in check, their main purpose was to prevent starvation. Of course, our diet and activity patterns have changed a lot since the Stone Age, but our body chemistries work the same. When our weight-regulating systems sense we're not getting enough to eat, hunger-stimulating hormones arouse powerful cravings, and energy-regulating hormones reduce the rate at which our bodies burn calories. The desire to eat dominates our thoughts, and our bodies do everything they can to replenish fat.
So the reason you're overweight is not that you lack willpower. It's because something upset the systems that match your caloric intake with your energy expenditure. Certainly, choices were involved. You influenced the form those calories took—whether they were carbohydrates, fats, or protein—but your body's weight-regulating mechanisms determined how much food you needed to quell your hunger. You can't ignore those instincts. Mustering up the discipline to starve yourself is not the answer. You need an approach that doesn't rely on willpower.
But if you have such little control over how much you eat, how can you lose weight? It's easier than you think, but you just can't do it by a frontal assault on deeply rooted survival instincts.
There are dozens of ways to lose weight. You can cut fats, cut carbs, count calories, fast, go on an exercise kick, or have your stomach stapled. But if a particular problem—say a hormonal imbalance, a lifestyle quirk, or a certain kind of food—caused you to gain weight, does it make sense to starve yourself without trying to correct the conditions that caused the problem in the first place? If you don't fix what's wrong, whatever caused you to gain weight is bound to come back and haunt you.
Unlocking the Mystery of Obesity
In recent years, billions of dollars have been spent on researching human metabolism, and indeed, medical science has made major breakthroughs in solving the mystery of obesity. Although these advances have been obscured by the usual controversy, junk science, and diet hype that surround the issue of weight loss, old ways of thinking are being turned upside down. Scientists now have a clearer idea of why people's weight-regulating mechanisms fall out of kilter and what can be done to put them back in balance. Here is the picture that is emerging.
If you're like most overweight people, three conditions converged to cause you to accumulate excess fat:
1. You inherited a common genetic quirk that affects a type of muscle fiber in your body called a slow-twitch fiber, making these muscles resistant to the effects of insulin, a hormone needed to metabolize the sugar glucose.
2. Lack of regular activation of your slow-twitch fibers causes them to spend too much time in a metabolically dormant state in which they don't respond normally to insulin, a condition called insulin resistance.
3. The insensitivity of your muscles to insulin makes you vulnerable to the harmful effects of dietary starch, the main ingredient of "white" carbohydrates like bread, potatoes, and rice. Starch releases more glucose into your bloodstream and does it faster than any other kind of food.
If your muscles are resistant to insulin and you consume quantities of starch typical of our modern diet, your pancreas gland has to make five or six times the normal amount of insulin to handle the glucose in your blood. And that's the problem. Insulin is a powerful obesity-promoting hormone—scientists call it the "feasting hormone." It triggers overeating and encourages your body to store calories as fat. Try as you will, you can't keep the pounds off.
There's another problem with starch: instead of traversing the full twenty-two feet of your digestive tract as other foods do, it short-circuits into your bloodstream in the first foot or two. It never reaches the last part of your intestine, where certain appetite-suppressing hormones come from. Even though starch is chock-full of calories, a few hours after eating it, you're hungry again.
Sleuthing the Hormonal Culprit: Syndrome X
Doctors have known for years that certain medical conditions can throw people's weight-regulating mechanisms out of kilter. The best known of these conditions is hypothyroidism, an under-active thyroid gland. Many folks wish they had this condition because it's so easy to correct with pills. However, most people's weight problems are not caused by thyroid trouble.
Although doctors have known for years of conditions that cause obesity in some people, until recently they couldn't pinpoint what caused most people's weight gain. Whatever it was, though, it was apparent that it was extremely common, the modern lifestyle aggravated it, and it got worse with age. Then scientists got a clue from doctors who took care of heart patients. In the 1980s, clinicians began to notice that patients who had heart attacks had an unusually high incidence of the following physical characteristics and laboratory findings:
Visceral adiposity, a tendency to accumulate fat in the abdomen
High blood levels of a type of fat called triglyceride
Low blood levels of HDL, a protective kind of cholesterol particle also called "good cholesterol"
Mildly elevated blood pressure
Borderline high blood glucose levels
When several of these findings occurred in the same individual, it raised the risk of blood vessel blockages even when blood cholesterol levels were normal. Not knowing what caused this phenomenon, doctors called it syndrome X or the metabolic syndrome.
Solving the Mystery: Insulin Resistance
Recently, researchers solved the mystery of syndrome X. It's caused by insulin resistance. This discovery was to turn the world of nutrition upside down and invalidate much of what doctors previously believed about diet, obesity, and heart disease. It also explained why excessive dietary starch and physical inactivity make some people gain weight but not others.
Insulin resistance isn't exactly a disease—it's a variation in the way people's bodies process carbohydrates, foods your body breaks down to glucose. About 22 percent of the American population can't handle the starch and sugar in their diets without producing excessive insulin. Although these folks usually have a genetic propensity to insulin resistance, having the tendency doesn't necessarily cause the condition. People who are hereditarily predisposed can go their entire lives without manifesting it. Something else—something in their activity and eating patterns—has to bring it on.
Insulin resistance is basically a muscle problem. Your muscles are the main users of glucose, and insulin regulates their consumption. Exercise increases your muscles' responsiveness to insulin, so they take up more glucose. Inactivity decreases their sensitivity, so they take up less. While the lack of physical activity that characterizes the typical modern lifestyle causes some degree of insulin resistance in everybody, it renders the muscles of genetically prone individuals particularly insensitive to insulin.
Although lack of physical activity brings on insulin resistance, this wouldn't be such a problem if we ate only meat and raw vegetation, as our prehistoric ancestors did. The body doesn't need much insulin to handle those foods. Meat contains virtually no glucose, and the glucose in fresh fruit and vegetables trickles into our bloodstreams slowly, requiring only small amounts of insulin. The only foods in our diet that call for large amounts of insulin are refined carbohydrates. Insulin resistance becomes a problem only when we consume more starch and sugar than our bodies can handle.
There's another important factor that brings on insulin resistance: being overweight itself. It's a vicious cycle. Weight gain worsens insulin resistance, and insulin resistance, in turn, promotes more weight gain. Even if you weren't insulin resistant to begin with, if you're overweight, you're more insulin resistant now than you were before. Insulin resistance locks you into being overweight.
The Thrifty-Gene Hypothesis
Why are so many of us genetically prone to such a troublesome condition as obesity? One benefit of being overweight is that you can withstand starvation better than thinner folks can. In ancient times, when humans regularly went long periods without food, the ability to store up calories as fat was an advantage. Because this trait increased the chances of survival during famine, more and more humans passed it on to the next generation. Biologists call this explanation for why we get fat the "thrifty-gene hypothesis."
Did the tendency to store excess fat predispose our ancestors to diabetes and heart disease? Undoubtedly, it did, but in prehistoric times, people rarely lived long enough to develop such problems. In the Stone Age, the average life span was less than thirty years. Also, people's diet and activity patterns helped protect them from these conditions.
How Insulin Resistance Affects Your Health
Excessive demands for insulin, high blood triglyceride levels, and wide fluctuations of blood glucose levels typical of unchecked insulin resistance cause myriad health problems, including the following:
Type 2 diabetes: If insulin production can't keep up with demand, glucose levels begin to rise, causing the condition called type 2 diabetes. Uncontrolled diabetes literally sugarcoats tissues and can eventually lead to eye, kidney, and blood vessel damage.
Islet cell burnout: The islet cells of the pancreas, which secrete insulin, also make a substance called amylin. When they secrete excessive amounts of insulin they also produce excessive amylin. High concentrations of amylin turn into an insoluble sludge called amyloid that damages the very cells that secrete it. Biopsies of the pancreases of patients with type 2 diabetes often show replacement of insulin-secreting cells by amyloid.
Hypoglycemia (low blood sugar): One of the earliest signs of insulin resistance is what's commonly called "low blood sugar." It might seem strange that a condition that leads to high blood sugar could cause low blood sugar, but when insulin-resistant individuals go three or four hours without eating, they often experience weakness, poor concentration, and a strong craving for food, all of which are promptly relieved by eating. Actually, the term "low blood sugar" is a misnomer. When the pancreas has to make large amounts of insulin, it often overshoots, causing glucose levels to fall too fast. This triggers a surge of another hormone, adrenaline, which stops glucose from falling. It's the adrenaline—not low blood glucose—that causes the shakiness and poor concentration typical of hypoglycemia. Adrenaline highs and lows typically occur several times a day, causing quirky eating patterns, frayed nerves, and end-of- the-day fatigue.
Heart and blood vessel disease: When your body gets more glucose than it can handle, your liver turns the excess to fat globules, which travel through your bloodstream to your fat deposits in the form of triglyceride. Although triglyceride doesn't damage arteries directly, high concentrations reduce blood levels of "good cholesterol," HDL, which raises the risk of blood vessel disease even when bad cholesterol levels are normal. (I talk about this more in Chapter 11.)
Menstrual difficulties: In women, insulin resistance sometimes brings on polycystic ovary syndrome (PCOS), which causes irregular periods, ovarian cysts, abnormal hair growth, and acne. PCOS is the leading cause of female infertility in the United States, affecting approximately 6 percent of women. It can be treated with a low-starch diet, exercise, and insulin-sensitizing medication.
Sleep apnea: Accumulation of fat in the abdomen and neck typical of insulin resistance interferes with breathing during sleep. This causes excessive snoring and aggravates sleep apnea, a form of erratic breathing that robs sleep of its restfulness.
Excerpted from The Glycemic Load Diet by ROB THOMPSON Copyright © 2012 by Robert Thompson and Dana Carpender. Excerpted by permission of McGraw-Hill. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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