Ending the War on Fat, Part 2



   The Fat Man

We have long been told that fewer calories and more exercise leads to weight loss. And we want to believe that science is purely a matter of data–that superior research will always yield the right answer.
But sometimes research is no match for a strong personality. No one better embodies that than Dr. Ancel Keys, the imperious physiologist who laid the groundwork for the fight against fat. Keys first made his name during World War II, when he was asked by the Army to develop what would become known as the K ration, the imperishable food supplies carried by troops into the field. It was in the following years that the fear of heart disease exploded in the U.S., driven home by President Dwight Eisenhower’s heart attack in 1955. That year, nearly half of all deaths in the U.S. were due to heart disease, and many of the victims were seemingly healthy men struck down suddenly by a heart attack.

“There was an enormous fear overtaking the country,” says Nina Teicholz, author of the new book The Big Fat Surprise. “The heart-disease epidemic seemed to be emerging out of nowhere.”

Keys had an explanation. He posited that high levels of cholesterol–a waxy, fatlike substance present in some foods as well as naturally occurring in the body–would clog arteries, leading to heart disease. He had a solution as well. Since fat intake raised LDL cholesterol, he reasoned that reducing fat in the diet could reduce the risk of heart attacks. (LDL cholesterol levels are considered a marker for heart disease, while high HDL cholesterol seems to be cardioprotective.) In the 1950s and ’60s, Keys sought to flesh out that hypothesis, traveling around the world to gather data about diet and cardiovascular disease. His landmark Seven Countries Study found that people who ate a diet low in saturated fat had lower levels of heart disease. The Western diet, heavy on meat and dairy, correlated with high rates of heart disease.


That study helped land Keys in 1961 on the cover of TIME, in which he admonished Americans to reduce the fat calories in their diet by a third if they wanted to avoid heart disease. That same year, following Keys’ strong urging, the American Heart Association (AHA) advised Americans for the first time to cut down on saturated fat. “People should know the facts,” Keys told TIME. “Then if they want to eat themselves to death, let them.”

Keys’ work became the foundation for a body of science implicating fat as a major risk factor for heart disease. The Seven Countries Study has been referenced close to 1 million times. The vilification of fat also fit into emerging ideas about weight control, which focused on calories in vs. calories out.
“Everyone assumed it was all about the calories,” says Lustig. And since fat contains more calories per gram than protein or carbohydrates, the thinking was that if we removed fat, the calories would follow.

That’s what Keys, who died in 2004, believed, and now it’s what most Americans believe too. But Keys’ research had problems from the start. He cherry-picked his data, leaving out countries like France and West Germany that had high-fat diets but low rates of heart disease. Keys highlighted the Greek island of Crete, where almost no cheese or meat was eaten and people lived to an old age with clear arteries.
But Keys visited Crete in the years following World War II, when the island was still recovering from German occupation and the diet was artificially lean. Even more confusing, Greeks on the neighboring isle of Corfu ate far less saturated fat than Cretans yet had much higher rates of heart disease.
“It was highly flawed,” says Dr. Peter Attia, the president and director of the Nutrition Science Initiative, an independent obesity-research center. “It was not on the level of epidemiology work today.”

Keys’ unshakable confidence and his willingness to take down any researcher who disagreed with him was at least as important as his massive data sets. (When the biostatistician Jacob Yerushalmy published a 1957 paper questioning the causal relationship between fat and heart disease, Keys responded sharply in print, claiming that Yerushalmy’s data was badly flawed.) Keys’ research also played into a prevailing narrative that Americans had once eaten a largely plant-based diet before shifting in the 20th century to meals rich in red meat. Heart disease followed, as if we were being punished for our dietary sins.

The reality is that hard numbers about the American diet are scant before midcentury and all but nonexistent before 1900. Historical records suggest Americans were always voracious omnivores, feasting on the plentiful wild game available throughout the country. In his book Putting Meat on the American Table, the historian Roger Horowitz concludes that the average American in the 19th century ate 150 to 200 lb. of meat per year–in line with what we eat now.


But the antifat message went mainstream, and by the 1980s it was so embedded in modern medicine and nutrition that it became nearly impossible to challenge the consensus. Dr. Walter Willett, now the head of the department of nutrition at the Harvard School of Public Health, tells me that in the mid- 1990s, he was sitting on a piece of contrary evidence that none of the leading American science journals would publish. “There was a strong belief that saturated fat was the cause of heart disease, and there was resistance to anything that questioned it,” Willett says. “It turned out to be more nuanced than that.” He had been running a long-term epidemiological study that followed the diets and heart health of more than 40,000 middle-aged men. Willett found that if his subjects replaced foods high in saturated fat with carbohydrates, they experienced no reduction in heart disease. Willett eventually published his research in the British Medical Journal in 1996.

In part because of Willett’s work, the conversation around fat began to change. Monounsaturated and polyunsaturated fats–the kind found in some vegetables and fish–were found to be beneficial to heart health. The Mediterranean diet, rich in fish, nuts, vegetables and olive oil, surged in popularity. And it’s worth noting that the Mediterranean diet isn’t low in total fat–not at all. Up to 40% of its calories come from poly- and monounsaturated fat. Today, medical groups like the Mayo Clinic embrace this diet for patients worried about heart health, and even the fat-phobic AHA has become receptive to it. “There is growing evidence that the Mediterranean diet is a pretty healthy way to eat,” says Dr. Rose Marie Robertson, the chief science officer of the AHA.

But what about saturated fat? Here, the popular wisdom has been harder to change. The 2010 USDA dietary guidelines recommend that Americans get less than 10% of their daily calories from saturated fat–the equivalent of half a pan-broiled hamburger minus the cheese, bacon and mayo it’s often dressed with. The AHA is even stricter: Americans over the age of 2 should limit saturated-fat intake to less than 7% of calories, and the 70 million Americans who would benefit from lowering cholesterol should keep it under 6% of calories–equal to about two slices of cheddar per day. Some experts say they just aren’t comfortable letting saturated fat off the hook. “When you replace saturated fats with polyunsaturated and monounsaturated fats, you lower LDL cholesterol,” says Dr. Robert Eckel, a past president of the AHA and a co-author of the group’s recent guidelines. “That’s all I need to know.”

But that’s not the full picture. The more we learn about fat, the more complex its effects on the body
appear.


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Part 3 -  here




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Ending the War on Fat


By Bryan Walsh

For decades, it has been the most vilified nutrient in the American diet. But new science reveals fat isn’t what’s hurting our health

The taste of my childhood was the taste of skim milk. We spread bright yellow margarine on dinner rolls, ate low-fat microwave oatmeal flavored with apples and cinnamon, put nonfat ranch on our salads. We were only doing what we were told. In 1977, the year before I was born, a Senate committee led by George McGovern published its landmark “Dietary Goals for the United States,” urging Americans to eat less high-fat red meat, eggs and dairy and replace them with more calories from fruits, vegetables and especially carbohydrates.

By 1980 that wisdom was codified.
The U.S. Department of Agriculture (USDA) issued its first dietary guidelines, and one of the primary directives was to avoid cholesterol and fat of all sorts. The National Institutes of Health recommended that all Americans over the age of 2 cut fat consumption, and that same year the government announced the results of a $150 million study, which had a clear message: Eat less fat and cholesterol to reduce your risk of a heart attack.

The food industry–and American eating habits–jumped in step. Grocery shelves filled with “light” yogurts, low-fat microwave dinners, cheese-flavored crackers, cookies. Families like mine followed the advice: beef disappeared from the dinner plate, eggs were replaced at breakfast with cereal or yolk-free beaters, and whole milk almost wholly vanished. From 1977 to 2012, per capita consumption of those foods dropped while calories from supposedly healthy carbohydrates increased–no surprise, given that breads, cereals and pasta were at the base of the USDA food pyramid.

                                                           Photo: USDA (flickr)

We were embarking on a “vast nutritional experiment,” as the skeptical president of the National Academy of Sciences, Philip Handler, put it in 1980. But with nearly a million Americans a year dropping dead from heart disease by the mid-’80s, we had to try something.

Nearly four decades later, the results are in: the experiment was a failure. We cut the fat, but by almost every measure, Americans are sicker than ever. The prevalence of Type 2 diabetes increased 166% from 1980 to 2012. Nearly 1 in 10 American adults has the disease, costing the health care system $245 billion a year,and an estimated 86 million people are prediabetic. Deaths from heart disease have fallen–a fact that many experts attribute to better emergency care, less smoking and widespread use of cholesterol- controlling drugs like statins–but cardiovascular disease remains the country’s No. 1 killer. Even the increasing rates of exercise haven’t been able to keep us healthy. More than a third of the country is now obese, making the U.S. one of the fattest countries in an increasingly fat world. “Americans were told to cut back on fat to lose weight and prevent heart disease,” says Dr. David Ludwig, the director of the New Balance Foundation Obesity Prevention Center at Boston Children’s Hospital. “There’s an overwhelmingly strong case to be made for the opposite.”

But making that case is controversial, despite the evidence to support it. The vilification of fat is now deeply embedded in our culture, with its love-hate relationship with food and its obsession over weight. It has helped reshape vast swaths of agriculture, as acre upon acre of subsidized corn was planted to produce the sweeteners that now fill processed foods. It has changed business, with the market for fat replacers–the artificial ingredients that take the place of fat in packaged food–growing by nearly 6% a year. It’s even changed the way we talk, attaching moral terms to nutrients in debates over “bad” cholesterol vs. “good” cholesterol and “bad” fat vs. “good” fat.

All of this means the received wisdom is not going to change quietly.
“This is a huge paradigm shift in science,” says Dr. Eric Westman, the director of the Duke Lifestyle Medicine Clinic, who works withpatients on ultra-low-carb diets. “But the studies to support it do exist.”

Research that challenges the idea that fat makes people fat and is a dire risk factor for heart disease is mounting. And the stakes are high–for researchers, for public-health agencies and for average people who simply want to know what to put in their mouth three times a day.



We have known for some time that fats found in vegetables like olives and in fish like salmon can actually protect against heart disease. Now it’s becoming clear that even the saturated fat found in a medium-rare steak or a slab of butter–public-health enemies Nos. 1 and 2–has a more complex and, in some cases, benign effect on the body than previously thought. Our demonization of fat may have backfired in ways we are just beginning to understand. When Americans cut back, the calories from butter and beef and cheese didn’t simply disappear. “The thinking went that if people reduced saturated fat, they would replace it with healthy fruits and vegetables,” says Marion Nestle, a professor of nutrition, food studies and public health at New York University. “Well, that was naive.”

New research suggests that it’s the overconsumption of carbohydrates, sugar and sweeteners that is chiefly responsible for the epidemics of obesity and Type 2 diabetes. Refined carbohydrates–like those in “wheat” bread, hidden sugar, low-fat crackers and pasta–cause changes in our blood chemistry that encourage the body to store the calories as fat and intensify hunger, making it that much more difficult to lose weight. “The argument against fat was totally and completely flawed,” says Dr. Robert Lustig, a pediatrician at the University of California, San Francisco, and the president of the Institute for Responsible Nutrition. “We’ve traded one disease for another.”

The myopic focus on fat has warped our diet and contributed to the biggest health crises facing the country. It’s time to end the war.


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