Good Calories, Bad Calories Part 47

Return to text.

*45 In 2003, for instance, the National Cholesterol Education Program described the shift in emphasis from total cholesterol to LDL cholesterol this way: "Many earlier studies measured only serum total cholesterol, although most of total cholesterol is contained in LDL. Thus, the robust relationship between total cholesterol and [coronary heart disease] found in epidemiological studies strongly implies that an elevated LDL is a powerful risk factor [my italics]."

Return to text.

46 In the technique described by Fredrickson, Levy, and Lees, LDL cholesterol is not measured directly but calculated from the measurements of triglycerides, HDL cholesterol, and total cholesterol.

Return to text.

*47 Those that did mention the effect of carbohydrates on HDL cholesterol rejected the relevance to heart disease, on the basis, as the American Heart a.s.sociation explained, "that epidemiological studies have demonstrated an inverse relation between carbohydrate consumption and risk for CHD."

Return to text.

*48 The nutritional const.i.tuents of such a piece of relatively fatty meat can be found in the Nutrient Database for Standard Reference at the USDA Web site, along with those of thousands of other foods.

Return to text.

*49 To be precise, Krauss says, he rediscovered this heterogeneity of LDL: Waldo Fisher of the University of Florida, and Verne Schumaker of the University of California, Los Angeles, had discovered it independently a decade earlier, but had not pursued it further.

Return to text.

*50 This suggests that saturated fat elevates LDL-cholesterol levels in part by increasing the amount of cholesterol in the LDL, and so making larger and fluffier LDL to begin with, rather than by increasing the number of LDL particles or by increasing the number of smal , dense LDL particles.

Return to text.

*51 What used to be known as juvenile-onset diabetes, which is characterized by an insulin deficit, is referred to as Type 1 or insulin-dependent diabetes mel itus, IDDM. The less severe form, which is characterized by insulin resistance rather than a lack of insulin, used to be cal ed adult-onset diabetes. It is now cal ed Type 2 or non-insulin-dependent diabetes mel itus or NIDDM. This is the terminology that I'l now use as wel .

Return to text.

*52 Named after Frederick Banting, the co-discoverer of insulin, a distant relative of Wil iam Banting, of corpulence notoriety.

Return to text.

*53 The reports do acknowledge, as the AHA-NIH-ADA conference report put it, that "very high-carbohydrate diets may accentuate atherogenic dyslipidemia"-i.e., smal , dense LDL, high triglycerides, and low HDL-but then it recommends a high-carbohydrate, low-saturated-fat diet as the treatment.

Return to text.

*54 Ralph DeFronzo, on the other hand, believes that sufficient studies have confirmed Stout's observations and that insulin itself should thus be considered an "atherogenic hormone."

Return to text.

*55 This hypothesis cannot, however, explain why atherosclerosis among diabetics has remained relatively impervious to the otherwise beneficial effects of insulin therapy to control blood sugar.

Return to text.

*56 Those in Cerami's laboratory at Rockefel er University and the researchers who trained with him get credit for much of the AGE work that fol owed.

Return to text.

*57 There's also evidence that HDL molecules can become glycated, inhibiting their function and "rendering the HDL more pro-atherogenic."

Return to text.

*58 For this reason, fructose is referred to as the most lipogenic carbohydrate. Credit for this observation dates to 1916, to Harold Higgins of the Nutrition Laboratory of the Carnegie Inst.i.tution.

Return to text.

*59 Individuals with a single copy of this apo E4 gene are nearly three times as likely to have both heart disease and Alzheimer's than those with none.

Apo E4 is a cousin of apo B, the protein component of LDL and VLDL, and it is also found in the lipoproteins that transport triglycerides and cholesterol.

Because heart-disease researchers have focused on cholesterol as the cause of heart disease, Alzheimer's researchers tend also to refer to apo E4 as involved in cholesterol transport as though that were al it did, thus "point[ing] to a link between cholesterol and Alzheimer's." But this took the overly simplistic 1960s view of heart disease and used it to misdirect the Alzheimer's research.

Return to text.

*60 Harvard neurologist Dennis Selkoe and others have been working to track down a gene that seems to predispose individuals to age-related Alzheimer's, rather than the inherited early-onset form. By February 2007, they had not found it, but they had localized it, in the lingo, to a chunk of a single chromosome that was known to include the gene for insulin-degrading enzyme. This made IDE the obvious candidate and suggested that anyone who inherited a particularly unlucky variant of the IDE gene would have an increased likelihood of getting Alzheimer's.

Return to text.

*61 Higginson held the environmental movement responsible for what he considered a wil ful misinterpretation of the epidemiologic observations: "If they could possibly make people believe that cancer was going to result from pol ution, this would enable them to facilitate the clean-up of water, of the air, or whatever it is," he told Science in 1979. He was al for cleaning up the environment, he added, but "to make cancer the whipping boy for every environmental evil may prevent effective action when it does matter."

Return to text.

*62 Those clinical trials that tested the dietary-fat-and-fiber hypotheses of cancer, as we discussed earlier, replaced red meat in the experimental diets with fruits, vegetables, and whole grains. When these trials failed to confirm that fat causes breast cancer, or that fiber prevents colon cancer, they also failed to confirm the hypothesis that red-meat consumption plays a role in either.

Return to text.

*63 Tannenbaum actual y compared his chronical y underfed mice with control mice fed the identical diet but supplemented with cornstarch. The inhibition of cancer, as Tannenbaum noted, could have been due to "carbohydrate-restriction" rather than restriction of al calories.

Return to text.

*64 Different IGFs have different effects. To keep the fol owing discussion reasonably simple, I'l refer to IGF and IGF receptors as though there were only one species of each, although I'm oversimplifying the science by doing so.

Return to text.

*65 The apparent severity of this epidemic is inflated by the way in which obesity is defined. The use of a threshold for establishing whether or not you're obese-a body ma.s.s index (BMI) of 30-means that one can move from the overweight category to the obese category by virtue of gaining a few pounds. As a result, the 10-percent rise in obesity between 1991 and 2000 actual y represented an increase in the average BMI of Americans from 26.7 to 28.1, an average weight gain of seven to ten pounds.

Return to text.

*66 Between the second and third National Health and Nutrition Examination Study.

Return to text.

*67 The USDA has a variety of mechanisms for estimating macronutrient intake-i.e., protein, carbohydrates, and fat-and has published a variety of reports on the subject. Not al are consistent, but the findings on fat consumption are. For instance, in April 1998, the USDA published an article ent.i.tled "Is Total Fat Consumption Real y Decreasing?" This article reported that average total fat consumption for men aged nineteen to fifty, for instance, dropped from 113 grams per day in 197778 to ninety-six in 1989, the period that encompa.s.ses the beginning of the obesity epidemic. The relevant numbers for women of the same age group are seventy-three grams of fat per day in 197778 and sixty-two in 1989.

Return to text.

*68 According to the Sporting Goods Manufacturers a.s.sociation, sales of sporting equipment, apparel, and shoes increased from $21.9 bil ion in 1987 (the earliest year for which they have data) to $52 bil ion in 2004.

Return to text.

*69 If each Pima drank two eight-ounce soft drinks a day, this would add roughly two hundred calories a day to Hesse's estimate of both carbohydrate and calorie consumption, and so would drop the fat in the diet to 22 percent.

Return to text.

*70 The Sioux were "essential y carnivorous" prior to their reservation life, the report noted, and so they "were never in the habit of eating much fruit and vegetables."

Return to text.

*71 Hrdli ka did publish a list of diseases treated by the local agency physician, which did include one case of diabetes.

Return to text.

*72 In 1804 and 1805, when the Corps of Discovery under Meriwether Lewis and Wil iam Clark made their historic overland expedition to the Pacific Ocean, they described game so plentiful in places that they literal y had to club it out of their way to make progress.

Return to text.

*73 This conclusion was supported four years later, when German researchers published their protocol for keeping these desert sand rats healthy in captivity. "It is wel known that these animals wil develop diabetes mel itus soon after their natural vegetative diet is removed and replaced with standard laboratory rations," they noted. But both diabetes and obesity can be avoided if the animals are reared on a suitable diet: in this case, fruits, vegetables, and herbs, supplemented by an unlimited supply of insects, shrimps, worms, and gra.s.shoppers.

Return to text.

*74 If the surgery is done to rodents during hibernation, they wil somehow slow the rate at which they draw on their fat supplies for fuel so as to compensate for the loss.

Return to text.

*75 The diet const.i.tuted roughly 400 calories a day of protein, 270 calories of fat, and 900 calories of carbohydrates.

Return to text.

*76 Though Stunkard's a.n.a.lysis has widely been perceived as a condemnation of al methods of dietary treatment of obesity, the studies he reviewed included only semi-starvation, calorie-restricted diets.

Return to text.

*77 Physical activity is the primary determinant of the variation in energy intake in human populations, as Walter Wil ett and his Harvard col eague Meir Stampfer note in the 1998 textbook Nutritional Epidemiology:"Indeed, in most instances, energy intake can be interpreted as a crude measure of physical activity...."

Return to text.

*78 When Mayer wrote about this research, or when he spoke to reporters about it, he would often give the impression that it included multiple studies in animals and humans-"J. Mayer has since demonstrated, in both animal and human studies...," as he would write in Science in 1967. This was technical y true, in that he had performed studies of both humans and animals-one study of each.

Return to text.

*79 Tanner did believe that Wil iam Banting's French predecessor Jean-Francois Dancel had final y provided a "more sure basis" for the treatment of obesity, and that Banting himself deserved credit for "bringing the subject before the public in a plain and sensible manner."

Return to text.

*80 It also a.s.sumes that the ingestion of food greater than that required by the body won't lead to a compensatory increase in energy expenditure, which is a point we'l discuss at length in the next chapter.

Return to text.

*81 This left von Noorden explaining that the detection of a r.e.t.a.r.ded metabolism seemed to require "special knowledge and ac.u.men on the part of the observer," and he acknowledged that even he lacked sufficient expertise. Hence, the only way to diagnose a r.e.t.a.r.ded metabolism was by implication: if the patient's weight could not be "brought under control through intel igent regulation of diet and exercise," then the patient probably had a r.e.t.a.r.ded metabolism. The circularity of this argument was evidently not apparent to him.

Return to text.

*82 This notion has survived in the suggestion that weight gain in children is exacerbated by the refusal of parents to al ow their children to walk or ride to school, for fear they wil be kidnapped or abused by strangers.

Return to text.

*83 The common response to confronting this dilemma, as Bennett noted, "is to ignore it," which is what happened to Bennett's commentary, even though he discussed this issue at a 1986 obesity conference hosted by the New York Academy of Sciences and attended by many of the prominent authorities in the field.

Return to text.

*84 That the toxic-environment hypothesis is deeply immersed in moral and cla.s.s judgments is evidenced by the observation that few or none of the condemnations of fast-food restaurants include a coffee chain such as Starbucks, despite the copious excess calories it peddles. A "grande" (sixteen ounces) Tazo Chai Creme Frappuccino, for instance, with whipped cream has roughly 510 calories, equivalent to a quarter-pounder with cheese at McDonald's. The same judgments are made when discussing physical activity: If we sit around al day watching television, we're condemned as couch potatoes, and our obesity is only a matter of time. If we sit around studying or reading books, this same accusation is rarely voiced.

Return to text.

*85 These observations do not contradict Magnus-Levy's. Magnus-Levy compared lean and obese subjects. These latter observations compare those who gain weight to those who don't; this difference, as we'l see, is critical.

Return to text.

*86Obesity and Leanness was the first serious book on obesity published after 1900, when von Noorden published Die Fettsucht. In the years since, there have been only half a dozen similar attempts (out of the innumerable professional texts and proceedings now available) to present a comprehensive and balanced a.n.a.lysis of the evidence, and only three come close to Obesity and Leanness in critical a.n.a.lysis-the chapters on obesity and undernutrition in the 1933 English translation of Eric Grafe's Metabolic Diseases and Their Treatment, Hilde Bruch's Importance of Overweight, and, a distant fourth, John Garrow's Energy Balance and Obesity in Man.

Return to text.

*87 A hormone also secreted by the pancreas that tends to counteract the effects of insulin.

Return to text.

*88 This phenomenon led to the notion of low-protein diets for weight loss. Regrettably, the ability to burn off excess calories when consuming a protein-deficient diet appears to be specific to young animals, and maybe even young pigs. When researchers tried to replicate this result in other animals-rats, sheep, cattle, or even older pigs-they noted that the animals eating the lower-protein diet got considerably fatter. They had more fat and less muscle, even if they weighed the same as the control animals.

Return to text.

*89 Although, as we discussed in Chapter 16, the total energy expenditure of obese individuals is likely to be greater, because they have, simply put, more pounds to expend energy and generate heat.

Return to text.

*90"The mean diet for j.a.panese people," Nishizawa et al. reported, citing a 1972 survey by the Ministry of Health and Welfare, "consists of 359 g of carbohydrate, 50.1 g of fat, 82.9 g of protein and a total of 2,279 calories."

Return to text.

*91"Obesity itself," as the National Academy of Sciences noted in 1989, "has not been found to be a.s.sociated with dietary fat in either inter-or intra-population studies."

Return to text.

*92 The Duke University pediatrician James Sidbury, Jr., who would go on to become director of the National Inst.i.tute of Child Health and Human Development, made the same observation about the obese children he treated in the early 1970s: "A pattern of constant nibbling was consistently found.

Most common snack foods are predominantly carbohydrate: crackers, potato chips, french fries, cookies, soft drinks, and the like."

Return to text.