Why We Get Fat: And What to Do About It (29 page)

This approach makes sense. But one other factor has to be taken into account: allowing some carbohydrates into the diet for some individuals may be like allowing ex-smokers a few cigarettes or reformed alcoholics the occasional drink.
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Some may be able to deal with it; some may find it is a slippery slope. The occasional
dessert on special occasions may become a weekly luxury, then biweekly, and finally nightly, and suddenly you’ve decided that carbohydrate restriction failed as a weight-loss regimen because you failed to stick with it and regained the weight.

A common argument that many experts wield against carbohydrate restriction is that
all
diets fail, the reason being that people just don’t stay on diets. So why bother? But this argument implicitly assumes that all diets work in the same way—we consume fewer calories than we expend—and thus all fail in the same way.

But this isn’t true. If a diet requires that you semi-starve yourself, it will fail, because (1) your body adjusts to the caloric deficit by expending less energy, (2) you get hungry and stay hungry, and (3), a product of both of these, you get depressed, irritable, and chronically tired. Eventually you go back to eating what you always did—or become a binge eater—because you can’t abide semi-starvation and
its
side effects indefinitely.

When you restrict fattening carbohydrates, however, you don’t have to restrict consciously how much you eat; indeed, you shouldn’t try. You can eat all you want of protein and fat, so you don’t get hungry and you don’t expend less energy. You might even expend more. The biggest challenge is the craving for carbohydrates. The hunger that accompanies our attempts to eat fewer calories is an unavoidable physiological phenomenon; the craving for carbohydrates is more like an addiction. It is the consequence, at least in part, of insulin resistance and the chronically elevated levels of insulin that go with it, and thus caused by the carbohydrates in the first place.

Sugars are a special case. As I discussed earlier, sugar appears to be addictive in the brain in the same way in which cocaine, nicotine, and heroin are. This suggests that the relatively intense cravings for sugar—a sweet tooth—may be explained by the intensity of the dopamine secretion in the brain when we consume sugar.

Whether the addiction is in the brain or the body or both, the
idea that sugar and other easily digestible carbohydrates are addictive also implies that the addiction can be overcome if you make the effort and have sufficient patience. This is not the case with hunger itself. Avoiding carbohydrates will lower your insulin level. Given time, this should reduce or eliminate the cravings. It could, however, take longer than you’d expect or ideally like. In 1975, the Duke University pediatrician James Sidbury, Jr. (who would become director that same year of the National Institute of Child Health and Human Development at the National Institutes of Health), reported great success slimming down obese children on a diet of only 15 percent carbohydrates. “After a year to 18 months,” he wrote, “the craving for sweets is lost,” and the children often pinpointed when this happened to “within a specific one to two week period.”

If you continue to eat some of the fattening carbohydrates or allow yourself some sugar (or even, perhaps, artificial sweeteners), though, you may always have the cravings. You may always have what Stephen Phinney refers to as “intrusive thoughts of food.” Anecdotal evidence suggests this is the case, and that’s all we have to go on.

The implication is that for some, at least, long-term success may be more likely if no compromise is allowed. If you do compromise and eventually return to eating these carbohydrates in quantity, the only reasonable response if weight loss remains your goal will be to try again, just as smokers might try to quit numerous times before they ultimately succeed. There’s no other viable option when you find yourself eating fattening carbohydrates again and regaining weight. Try to quit again, or at least cut back to some minimal level.

If you have grown up with one belief system (with one paradigm, as sociologists of science say), it’s hard to leave it behind entirely
when you open your mind to accept another. We’ve been told for so long, and believed for so long, that a fundamental requirement for weight loss is that we eat less than we’d like, and for weight maintenance that we eat in moderation, that it’s natural to assume the same is true when we restrict the carbohydrates we eat. Eating less of everything, though, as I discussed earlier, is another way of saying that we’re going to restrict consciously the amount of protein and fat we consume, as well as the carbohydrates. But protein and fat don’t make us fat—only the carbohydrates do—so there is no reason to curtail them in any way.

It’s true that people who restrict carbohydrates often eat less than they otherwise might. A common experience is to give up fattening carbohydrates and find that you’re not as hungry as you used to be, that mid-morning snacks are no longer necessary. Intrusive thoughts of food and the urge to satisfy them vanish. But that’s because you’re now burning your fat stores for fuel, which you didn’t do before. Your fat cells are now working properly as short-term energy buffers, not long-term lockups for the calories they’ve sequestered. You have an internal supply of fuel that keeps you going throughout the day and night, as it should, and your appetite adjusts accordingly. If you’re not running short on fuel, you feel no need to restock every few hours. (If you’re losing two pounds a week, that’s seven thousand calories of your own fat that you’re burning for fuel every week—one thousand calories each day that you don’t have to eat.)

Another effect, though, of restricting carbohydrates is that your energy expenditure should increase. You’re no longer diverting fuel into your fat tissue, where you can’t use it, and so you literally have more energy to burn. By avoiding the fattening carbohydrates, you remove the force that diverts calories into your fat cells. Your body should then find its own balance between energy consumed (appetite and hunger) and energy expended (physical activity and metabolic rate). This process could take time, but it should happen without conscious thought.

Trying to rein in appetite consciously could lead to compensatory
responses. You might have less energy to burn, so your energy expenditure won’t increase, or you hold on to fat that you’d otherwise burn. You might lose lean tissue (muscle) that you might otherwise maintain. And the conscious self-restraint might prompt an urge to binge. Physicians who prescribe carbohydrate restrictions in their clinics say that their patients get the best results when they’re reminded or urged to eat whenever they’re hungry and until they’re satisfied or even to schedule snacks every few hours and eat whether they are hungry or not.

The same argument holds for exercise. There are very good reasons to be physically active, but weight loss, as I discussed earlier, does not appear to be one of them. Exercise will make you hungry, and it’s likely to reduce your energy expenditure during times when you’re not exercising. The goal is to avoid both of these responses. Trying to drive weight loss by increasing energy expenditure may be not only futile but also actively counterproductive. You tend to be sedentary when you’re overweight or obese because of the partitioning of fuel into your fat tissue that you could be burning for energy. You literally lack the energy to exercise, and so the impulse to do it. Once that problem is fixed—by avoiding the carbohydrates that made you and keep you fat—then you should have the energy to be physically active and with it the drive or impulse to do so.

The goal is to remove the cause of your excess adiposity—the fattening carbohydrates—and let your body find its own natural equilibrium between energy expenditure and consumption. So you should eat when you’re hungry and eat until you’re full. If you’re not eating carbohydrate-rich foods, you won’t get fat or fatter by doing so. Once you start burning your own fat for fuel, you should have the energy to be physically active as well.

Another hangover from the last half-century of dietary misguidance is the belief that dietary fat must indeed be bad for us, even if we accept that carbohydrates are causing us to fatten.

This is a compromise position that seems perfectly reasonable. It was this kind of thinking in the early 1960s that led proponents of carbohydrate restriction to describe their recommended diets as high in protein instead of high in fat. Rather than avoiding only the fattening carbohydrates, you eliminate butter and cheese from the diet, eat chicken breasts without the skin, lean fish, the leanest cuts of meat, and egg whites without the yolks.

As I’ve said, though, there’s no compelling reason to think that fat, or saturated fat, is harmful, whereas there’s good reason to question the benefits of diets that abnormally elevate the protein content. Populations that ate mostly meat or exclusively meat, as I discussed earlier, tried to maximize the fat they ate, and one reason seems to be that high-protein diets—without significant fat or carbohydrates—can be toxic. This issue has been addressed by protein-metabolism experts in a recent U.S. Institute of Medicine Report called
Dietary Reference Intakes
.

“It has been suggested from evidence of the dietary practices of hunter-gatherer populations, both present day and historical, that humans avoid diets that contain too much protein,” the IOM experts explain, citing the same research on hunter-gatherer populations to which I referred. The short-term symptoms of these high-protein,
low-fat
, low-carbohydrate diets, these protein-metabolism experts point out, are weakness, nausea, and diarrhea. These symptoms will disappear when the protein content is reduced to a more moderate 20 to 25 percent of calories and fat content is increased to compensate.

When physicians and nutritionists tested carbohydrate restriction before the beginning of the anti-fat movement in the 1960s, they did so with fatty meat and diets that were 75 to 80 percent fat
by calories but only 20 to 25 percent protein. This mixture had no side effects, was well tolerated, and is most consistent with the diets eaten by populations like the Inuits, who lived almost exclusively, if not exclusively, on animal products.

Whether or not a diet that is 75 percent fat and 25 percent protein is healthier than one that is 65 percent fat and 35 percent protein is an open question. Equally important is the question of which is easier to sustain and provides the most enjoyment. If you find yourself satisfied eating skinless chicken breasts, lean cuts of meat and fish, and egg-white omelets, so be it. But eating the fat of the meat as well as the lean, the yolk as well as the white, foods cooked with butter and lard may be the better prescription for sustainability, and it may be for health as well.

When you replace the carbohydrates you eat with fat, you’re creating a radical shift in the fuel that your cells will burn for energy. They go from running primarily on carbohydrates (glucose) to running on fat—both your body fat and the fat in your diet. This shift, though, can come with side effects. These can include weakness, fatigue, nausea, dehydration, diarrhea, constipation, a condition known as postural, or orthostatic, hypotension—if you stand up too quickly, your blood pressure drops precipitously, and you can get dizzy or even pass out—and the exacerbation of pre-existing gout. In the 1970s, the authorities insisted that these “potential side effects” were reasons why the diets could not “generally be used safely,” and the implication was that they shouldn’t be used at all.

But that was to confuse the short-term effects of what can be thought of as carbohydrate withdrawal with the long-term benefits of overcoming that withdrawal and living a longer, leaner, and healthier life. The more technical term for carbohydrate withdrawal is “keto-adaptation,” because the body is adapting to the
state of ketosis that results from eating fewer than sixty or so grams of carbohydrates a day. This reaction is why some who try carbohydrate restriction give it up quickly.
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(“Carbohydrate withdrawal is often interepreted as a ‘need for carbohydrate,’ ” says Westman. “It’s like telling smokers who are trying to quit that their withdrawal symptoms are caused by a ‘need for cigarettes’ and then suggesting they go back to smoking to solve the problem.”)

The reason for the side effects now appears to be clear, and physicians who prescribe carbohydrate restriction say they can be treated and prevented. These symptoms have nothing to do with the high fat content of the diet. Rather, they appear to be a consequence of either eating too much protein and too little fat, of attempting strenuous exercise without taking the time to adapt to the diet, or, in most cases, of the body’s failure to compensate fully for the restriction of carbohydrates and the dramatic lowering of insulin levels that ensues.

As I mentioned in passing earlier, insulin signals our kidneys to reabsorb sodium, which in turn causes water retention and raises blood pressure. When insulin levels drop, as they do when we restrict carbohydrates, our kidneys will excrete the sodium they’ve been retaining and with it water. For most people this is beneficial, and it’s the reason why blood pressure comes down with carbohydrate restriction. (This water loss, which can be a half-dozen pounds or more in a two-hundred-pounder, can constitute most of the early weight loss.) For some individuals, though, the body will perceive the water loss as something to be prevented. It does so through a web of compensatory responses that can lead to water retention and what are called electrolyte
imbalances (the kidneys excrete potassium to save sodium), and the result is the side effects just cited. The reaction can be countered, as Phinney has noted, by adding sodium back into the diet: taking a gram or two of sodium a day (a half to one teaspoon of salt) or drinking a couple of cups of chicken or beef broth daily, which is what Westman, Vernon, and other physicians now prescribe.

These side effects speak to the importance of having the guidance of a knowledgeable physician when making the decision to avoid fattening carbohydrates. If you happen to be diabetic or hypertensive, then a doctor’s guidance is critical. Since restricting carbohydrates will lower both blood sugar and blood pressure, if you’re already taking drugs to do the same, the combination can be dangerous. Abnormally low blood sugar (known as hypoglycemia) can cause seizures, unconsciousness, and even death. Abnormally low blood pressure (hypotension) can induce dizziness, fainting, and seizures.