The Low-Carbohydrate Way to Heart Disease

The Low-Carbohydrate Way to Heart Disease

How to avoid the cardiovascular problems associated with yo-yoing seems obvious, if not easy: Don’t regain the weight that has been lost. But that solution rests on the assumption that the health risks of dieting are caused only when weight is regained. Many diets can also cause damage even while the weight remains off. Consider one of the most popular weight-loss strategies of the past several decades: the low-carbohydrate diet.

This diet has a long history, dating back at least to the mid-1800s, when Dr. William Harvey, an English surgeon, prescribed a diet for one of his patients, William Banting, that was devoid of sweets and starches, but permitted unlimited quantities of meat. Banting was so pleased with the results that he popularized the diet in his 1862 Letter on Corpulence, Addressed to the Public. Variations of this diet surfaced over the years, but none to such spectacular success as was achieved by a spate of low-carbohydrate diet books a century later: Calories Don’t Count (1961), The Doctor’s Quick Weight Loss Diet (1967), and Dr. Atkins’ Diet Revolution: The High Calorie Way to Stay Thin Forever (1972), to name but a few; each soared to number one on the best-seller charts. Although shunning carbohydrates to shed pounds fell out of favor in the 1980s, the low-carbohydrate diet experienced a sensational resurgence in 1990s, with Dr. Atkins’ “New” Diet Revolution leading the way. Protein Power, Sugar Busters! Cut Sugar to Trim Fat, The Carbohydrate Addict’s Diet: The Lifelong Solution to Yo-Yo Dieting, and Suzanne Somers’ Eat Great, Lose Weight—again, just to mention a few—all soared to the top of the bestseller lists in the late 1990s.

Though most of these weight-loss plans were penned by physicians, they had unsuspected health consequences, which first came to light thanks to researchers at a number of institutions. In a study done by Harvard Medical School in association with Peter Bent Brigham Hospital in Boston, twelve young men and women who were hospital employees volunteered to try Dr. Irwin Stillman’s plan in The Doctor’s Quick Weight Loss Diet, which calls for 50 percent of the daily calorie intake to come from fat, 48 percent from protein, and a cholesterol consumption 4 times the recommended maximum. Even though their average weight dropped by about seven pounds during the period they remained on the diet (which ranged from three to seventeen days), the subjects saw their total blood cholesterol increase from an average of 215 mg/dl before the diet to 248, which placed them in the high-risk category for heart disease. (Their prediet level of 215 is about average for the U.S. population, but a little higher than the below-200 level that is recommended.) Most of the subjects complained of fatigue, mild nausea, and occasional diarrhea during the diet, and a few had to quit after just a few days because the symptoms interfered with their work. At the time the study was published, in 1974, more than 5 million copies of The Doctor’s Quick Weight Loss Diet had been sold.

Another study, involving twenty-four obese men and women, focused on the diet plan according to Dr. Atkins’ Diet Revolution, which calls for approximately two-thirds of the daily calories to come from fat, the rest from protein, and a cholesterol load nearly three times the recommended maximum. After eight weeks on the diet, the group’s LDL cholesterol-the bad kind, which promotes fatty buildup in the arteries-had increased by an average of 19 percent. The ten women in the study had even worse results: Although they had lost an average of fifteen pounds, their LDL cholesterol shot up by 33 percent. Their pre-diet LDL cholesterol level of 119 mg/dl was in the normal range. After just eight weeks on the Atkins’ diet, however, their LDL cholesterol rose to 158 mg/dl, which is just 2 points shy of the 160 mg/dl level considered “high risk.” To make matters worse, their HDL cholesterol-the good kind, which fights fatty buildup in the arteries-had decreased by 10 percent. The book (and all its subsequent spin-off versions) whose diet plan delivered these results is still wildly popular and remains a multimillion selling sensation thirty years after its initial publication.

While such findings may seem irrelevant to long-term health considerations, since most people get sick of these diets within a few days or weeks and go off them, the facts suggest otherwise. Atherosclerosis is a disease characterized not by a slow, steady narrowing of the blood vessels over time but by sudden spurts in the growth of the fat- and cholesterol-loaded deposits that clog arteries. An abrupt increase in cholesterol level, or a worsening of the ratio between bad and good cholesterol, could conceivably cause such spurts. Just a couple of weeks of staying at a high-cholesterol count of 248 mg/dl, which was the level reached by the men and women on Dr. Stillman’s diet, could do more harm than several years at a count of 215, the slightly higher-than-recommended level they were at prior to starting the diet.

Dieting Begets Bingeing, Which Begets…

Actually any diet, regardless of its composition, can provoke the artery-clogging process. This is because dieting frequently sets the stage for bingeing, particularly on foods that are not exactly what we would call heart-healthy. Intense cravings for foods laden with fat and sugar are common among dieters and are frequently mentioned by dieters as the primary reason for their failure to stick to a diet. In my experience, I have yet to meet a yo-yoer who went off a diet by grazing at a health food store.

No one knows precisely why dieting intensifies preferences for high-fat and sugar-loaded foods. Though there has been a lot of emphasis on the idea that the causes are cultural, having to do with the vast amounts of junk food advertising that are constantly beamed at us, there may also be a strong biological component. The fact that even laboratory rats develop strong preferences for fatty foods during the refeeding stage of a yo-yo cycle hints that the longing may be in our nature.

Worse news still comes from research done by Dr. Adam Drewnowski, professor of nutrition at the University of Michigan School of Public Health, which suggests that the more dieting a person does, the stronger the postdiet craving for foods high in fat and sugar. Since the mid-1980s Dr. Drewnowski has been searching for clues to what determines a person’s taste preferences. With regard to dieting, he has found that those most likely to exhibit strong fat and sugar cravings are women of above-average weight with a history of large weight fluctuations due to chronic dieting.

The negative effects of bingeing are not limited to weight gain. Bingeing on sweet, high-fat foods after each failed weight-loss attempt subjects the dieter’s blood vessels to the same kind of high-cholesterol stress described above, and that means the potential for an “atherosclerotic spurt,” with all the heart disease risks that such a spurt entails. Over the long haul there are also other kinds of risks to bingeing. High-fat, high-sugar foods promote the gain of bad body fat, which, as explained in the preceding chapter, can wreak havoc with both your cardiovascular system and your ability to properly metabolize your foods. Heart disease, as well as insulin resistance and, further down the line, type 2 diabetes, are the possible results of such nutritional abuse of your body.

It must be acknowledged that dieting does not always promote bingeing. Nonetheless it is well documented that most dieters will eventually regain most, if not all, the weight they lost. So it is important to emphasize that no matter how fast-or slow-weight is regained following a period of caloric restriction, the health of the dieter may be at risk. Just one weight-loss/gain cycle can impair glucose metabolism and elevate cholesterol, triglycerides, and blood pressures, even if the weight regain takes up to four years.

Furthermore there is recent evidence that chronic weight fluctuation may lead to “permanent” decreases in HDL cholesterol in women. A report published in the November 2000 issue of the Journal of the American College of Cardiology concluded, “Weight cycling is associated with lower HDL cholesterol in women of a magnitude that is known to be associated with an increased risk of cardiac events as demonstrated in prior clinical trials.” In this NIH-sponsored Women’s Ischemia Syndrome Evaluation (WISE) study, 27 percent of the 485 participants were classified as weight cyclers (defined as a weight loss of at least 10 pounds at least 3 times). As a group their HDL cholesterol levels were 7 percent lower than noncyclers. Even more alarming was the fact that the HDL cholesterol levels decreased in proportion to how much total weight was lost during each cycle. For example, women who lost 50 or more pounds during each weight-loss attempt had HDL cholesterol levels that were 27 percent lower than noncyclers (41 mg/dl versus 56 mg/dl). A 1 mg/dl decrease in HDL cholesterol corresponds to a 3 percent increase in heart disease risk in women; thus the “extreme” weight cyclers had a heart disease risk 45 percent higher than that of noncyclers. The researchers also noted that the true adverse effect of yo-yoing might have been underestimated because the women who reported a history of weight cycling were significantly more physically active than noncyclers. Since exercise is known to increase HDL cholesterol, the data suggest that with regard to “good” cholesterol the adverse effect of weight cycling is more powerful than the beneficial effect of exercise

Reprinted with permission from Big Fat Lies
by Glenn A. Gaesser, Ph.D.
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