domingo, 15 de junho de 2014

O fim da guerra à gordura - reportagem da revista TIME

Segue, abaixo, a íntegra da reportagem de capa da revista TIME dessa semana, encerrando o ciclo de 30 anos de orientação nutricional equivocada.

P.S.: A versão traduzida está aqui: http://www.paleodiario.com/2014/06/revista-time-terminando-guerra-gordura.html





Ending the War on Fat

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.

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 with patients 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.

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.

The Truth About Fat 

The idea that saturated fat is bad for us makes a kind of instinctive sense, and not just because we use the same phrase to describe both the greasy stuff that gives our steak flavor and the pounds we carry around our middles. Chemically, they’re not all that different. The fats that course through our blood and accumulate on our bellies are called triglycerides, and high levels of triglycerides have been linked to heart disease. It doesn’t take much of an imaginative leap to assume that eating fats would make us fat, clog our arteries and give us heart disease. “It sounds like common sense–you are what you eat,” says Dr. Stephen Phinney, a nutritional biochemist who has studied low-carb diets for years.

But when scientists crunch the numbers, the connection between saturated fat and cardiovascular disease becomes more tenuous. A 2010 meta-analysis–basically a study of other studies–concluded that there was no significant evidence that saturated fat is associated with an increased risk of cardiovascular disease. Those results were echoed by another meta-analysis published in March in the Annals of Internal Medicine that drew on nearly 80 studies involving more than half a million subjects. A team led by Dr. Rajiv Chowdhury, a cardiovascular epidemiologist at Cambridge University, concluded that current evidence does not support low consumption of saturated fats or high consumption of the polyunsaturated fats that are often considered heart healthy. Though the authors came under criticism for the way they evaluated the evidence, they stand behind the conclusion, noting that the aim of their study is to show the need for more research. “The main message is that there’s a lot more work that needs to be done,” says Chowdhury.

Given that the case on saturated fat was long considered closed, even calls to re-examine the evidence mark a serious change. But if the new thinking about saturated fats is surprising, it may be because we’ve misunderstood what meat and dairy do to our bodies. It’s incontrovertibly true that saturated fat will raise LDL-cholesterol levels, which are associated with higher rates of heart disease. That’s the most damning biological evidence against saturated fat. But cholesterol is more complicated than that. Saturated fat also raises levels of the so-called good HDL cholesterol, which removes the LDL cholesterol that can accumulate on arterial walls. Raising both HDL and LDL makes saturated fat a cardio wash.

Plus, scientists now know there are two kinds of LDL particles: small, dense ones and large, fluffy ones. The large ones seem to be mostly harmless–and it’s the levels of those large particles that fat intake raises. Carb intake, meanwhile, seems to increase the small, sticky particles that now appear linked to heart disease. “Those observations led me to wonder how strong the evidence was for the connection between saturated fat and heart disease,” says Dr. Ronald Krauss, a cardiologist and researcher who has done pioneering work on LDL. “There’s a risk that people have been steered in the wrong direction by using LDL cholesterol rather than LDL particles as a risk factor.”

It’s important to understand that there’s no such thing as a placebo in a diet study. When we reduce levels of one nutrient, we have to replace it with something else, which means researchers are always studying nutrients in relation to one another. It’s also important to understand that the new science doesn’t mean people should double down on cheeseburgers or stir large amounts of butter into their morning coffee, as do some adherents of ultra-low-carb diets. While saturated fat increasingly seems to have at worst a neutral effect on obesity and heart disease, other forms of fat may be more beneficial. There’s evidence that omega-3s, the kind of fat found in flaxseed and salmon, can protect against heart disease. A 2013 study in the New England Journal of Medicine found that a diet rich in polyunsaturated and monounsaturated fats significantly reduced the risk of major cardiovascular events.

And there is variety even within the category of saturated fats. A 2012 study found that fats in dairy–now the source from which Americans get most of their saturated fat–seem to be more protective than the fats found in meat. “The main issue here is comparative,” says Dr. Frank Hu, a nutrition expert at the Harvard School of Public Health. “What are you comparing saturated fat to?”



The Unintended Diet

The food industry is nothing if not inventive. Faced with a fatwa against fat in the 1980s, manufacturers adjusted, lining grocery shelves with low-fat cookies, crackers and cakes. The thinking for consumers was simple: Fat is dangerous, and this product has no fat; therefore it must be healthy. This was the age of SnackWells, the brand of low-fat cookies introduced by Nabisco in 1992 that within two years had surpassed the venerable Ritz cracker to become the No. 1 snack in the nation. But without fat, something had to be added, and Americans wound up making a dangerous trade. “We just cut fat and added a whole lot of low-fat junk food that increased caloric intake,” says Dr. David Katz, the founding director of Yale University’s Prevention Research Center. “It was a diet of unintended consequences.

Those consequences have been severe. From 1971 to 2000, the percentage of calories from carbohydrates increased nearly 15%, while the share of calories from fat fell–in line with expert recommendations. In 1992, the USDA recommended up to 11 servings a day of grains, compared with just two to three servings of meat, eggs, nuts, beans and fish combined. School districts across the country have banned whole milk, yet sweetened chocolate milk remains on the menu as long as it’s low-fat.

The idea here was in part to cut calories, but Americans actually ended up eating more: 2,586 calories a day in 2010 compared with 2,109 a day in 1970. Over that same period, calories from flour and cereals went up 42%, and obesity and Type 2 diabetes became veritable epidemics. “It’s undeniable we’ve gone down the wrong path,” says Jeff Volek, a physiologist at the University of Connecticut.

It can be hard to understand why a diet heavy on refined carbs can lead to obesity and diabetes. It has to do with blood chemistry. Simple carbs like bread and corn may not look like sugar on your plate, but in your body, that’s what they’re converted to when digested. “A bagel is no different than a bag of Skittles to your body,” says Dr. Dariush Mozaffarian, the incoming dean of nutrition science at Tufts University.

Those sugars stimulate the production of insulin, which causes fat cells to go into storage overdrive, leading to weight gain. Since fewer calories are left to fuel the body, we begin to feel hungry, and metabolism begins to slow in an effort to save energy. We eat more and gain more weight, never feeling full. “Hunger is the death knell of a weight-loss program,” says Duke’s Westman. “A low-fat, low-calorie diet doesn’t work.” Because as this process repeats, our cells become more resistant to insulin, which causes us to gain more weight, which only increases insulin resistance in a vicious circle. Obesity, Type 2 diabetes, high triglycerides and low HDL can all follow–and fat intake is barely involved. All calories, it turns out, are not created equal. “When we focus on fat, carbohydrates inevitably increase,” says Ludwig, who co-wrote a recent JAMA commentary on the subject. “You wouldn’t give lactose to people who are lactose intolerant, yet we give carbs to people who are carb intolerant.”

Ultra-low-carb diets have come in and out of vogue since Dr. Robert Atkins first began promoting his version nearly 50 years ago. (It has never been popular with mainstream medicine; the American Diabetic Association once referred to the Atkins diet as a “nutritionist’s nightmare.”) Studies by Westman found that replacing carbohydrates with fat could help manage and even reverse diabetes. A 2008 study in the New England Journal of Medicine that looked at more than 300 subjects who tried either a low-fat, a low-carb or a Mediterranean-style diet found that people on the low-fat diet lost less weight than those on the low-carb or Mediterranean diet, both of which feature high amounts of fat. Those results aren’t surprising–study after study has found that it’s very difficult to lose weight on a very low-fat diet, possibly because fat and meat can produce a sense of satiety that’s harder to achieve with carbs, making it easier to simply stop eating.

Not every expert agrees. Dr. Dean Ornish, founder of the nonprofit Preventive Medicine Research Institute, whose low-fat, almost vegan diet has been shown in one study to reverse arterial blockage, worries that an increase in animal-protein consumption can come with health problems of its own, pointing to studies that link red meat in particular to higher rates of colon cancer. There’s also the uncomfortable fact that meat, especially beef, has an outsize impact on the planet. Nearly a third of the earth’s total ice-free surface is used in one way or another to raise livestock. Even if eating more fat is better for us–which Ornish doesn’t believe–it could carry serious environmental consequences if it leads to a major increase in meat consumption. “These studies just tell people what they want to hear,” says Ornish. “There’s a reductionist tendency to look for the one magic bullet.”

The war over fat is far from over. Consumer habits are deeply formed, and entire industries are based on demonizing fat. TV teems with reality shows about losing weight. The aisles are still filled with low-fat snacks. Most of us still feel a twinge of shame when we gobble down a steak. And publishing scientific research that contradicts or questions what we have long been told about saturated fat can be as difficult now as it was for Willett in the ’90s. Even experts like Harvard’s Hu, who says people shouldn’t be concerned about total fat, draw the line at fully exonerating saturated fat. “I do worry that if people get the message that saturated fat is fine, they’ll [adopt] unhealthy habits,” he says. “We should be focusing on the quality of food, of real food.”

Nearly every expert agrees we’d be healthier if more of our diet were made up of what the writer Michael Pollan bluntly calls “real food.” The staggering rise in obesity over the past few decades doesn’t just stem from refined carbohydrates messing with our metabolism. More and more of what we eat comes to us custom-designed by the food industry to make us want more. There’s evidence that processing itself raises the danger posed by food. Studies suggest that processed meat may increase the risk of heart disease in a way that unprocessed meat does not.

How we eat–whether we cook it ourselves or grab fast-food takeout–matters as much as what we eat. So don’t feel bad about the cream in your coffee or the yolks in your eggs or the occasional steak with béarnaise if you’ve got the culinary chops–but don’t think that the end of the war on fat means all the Extra Value Meals you can eat. As Katz puts it, “the cold hard truth is that the only way to eat well is to eat well.” Which, I’m thankful to note, doesn’t have to include skim milk.

This appears in the June 23, 2014 issue of TIME.

quinta-feira, 12 de junho de 2014

A dieta de baixa gordura está morta - 4 - Capa histórica da revista TIME

OBITUÁRIO

Nascimento: 26 de março de 1984

Morte: 12 de junho de 2014

Obituário

Aos 30 anos, morre a dieta low fat. Concebida na década de 1970 com base em estudos epidemiológicos mal feitos, entronizada na diretrizes em 1977, e popularizada pela revista TIME em 1984 - tudo isso sem que NENHUM estudo houvesse sido conduzido para testar sua validade, e tendo sobrevivido bravamente a despeito de sua repetida refutação por ensaios clínicos randomizados e metanálises, foi ferida de morte em 2007 pela publicação de Good Calories, Bad Calories, tendo sangrado até 2013, quando uma sequência de estudos de grande impacto e editoriais em revistas médicas de grande prestígio a deixaram em condições críticas. Três meses após a publicação de uma metanálise definitiva, no dia de hoje, a dieta low fat morre pelas mãos da mesma publicação leiga que a entronizou 30 anos atrás. Mas continuará viva no receituário de médicos e nutricionistas cujo luto os impede de ver claramente, bem como na memória de todas as pessoas que comeram omeletes sem as gemas, peito de frango sem pele e que viraram uma estatística na epidemia de obesidade, síndrome metabólica e diabetes quando trocaram os ovos por açucarados cereais matinais (sem gordura) e o salmão por macarrão.

Descanse em paz.

Postagens relacionadas:

A dieta de baixa gordura está morta - 3

Repito o que escrevi numa das postagens acima:

A dieta de baixa gordura lembra muito uma galinha que continua correndo depois que sua cabeça já foi cortada - pode não parecer, mas já está morta. Hoje, para mim, está claro, olhando para trás, que low fat foi uma dessas anomalias históricas, uma espécie alucinação coletiva que se apossou da humanidade nos anos 1970. Esta foi - e sempre será - a verdadeira dieta da moda. Sua introdução (pelo departamento de agricultura dos EUA) desencadeou o maior desastre de saúde pública de que temos notícia - a epidemia de obesidade, síndrome metabólica e diabetes (veja aqui). Mas não passou, no fundo, de uma breve solução de continuidade dentro de uma evolução alimentar que jamais incluiu a restrição voluntária de calorias ou de gordura (pelo contrário, veja aqui)


Assim como Elvis, que continua vivo para alguns de seus fãs, tenho para mim que a moda low fat continuará viva nos estômagos famintos de seus seguidores e nas mentes dogmáticas de alguns profissionais de saúde. Mas - sinto dizer - Elvis morreu.


A biografia completa da falecida dieta pode ser conferida aqui:

quarta-feira, 11 de junho de 2014

Comer de 3/3 horas - má ideia

"Você precisa comer cada 3 horas para não sentir fome e não desacelerar o metabolismo". Quantas vezes você já ouviu essa afirmação? Inúmeras. É tão comum, que já virou uma espécie de truísmo: certamente, tantos profissionais não afirmariam algo assim se não fosse verdade, não é mesmo? Bom, o abismo entre a vulgata nutricional e a ciência parece nunca chegar ao fundo.

Vejam exemplos reais deste tipo de afirmação:

Neste (lamentável) site do Ministério da Saúde, podemos ver a orientação sem maiores explicações:
"[Devemos] desestimular "pular" as refeições"
O mesmo aqui: 
"Faça pelo menos três refeições (café da manhã, almoço e jantar) e dois lanches saudáveis por dia. Não pule as refeições. Fazendo todas as refeições, você evita que o estômago fique vazio por muito tempo, diminuindo o risco de ter gastrite e de ficar com muita fome e exagerar na quantidade quando for comer."


A melhor explicação da teoria, no entanto, achei no site da Sadia: 

"Comer de três em três horas traz diversos benefícios ao organismo. Entenda melhor! Responda rapidamente: quantas vezes você come por dia? Se sua resposta foi um número igual ou inferior a três, você deve ficar atento. O hábito de realizar pequenos lanches entre as refeições principais, ou seja, alimentar-se a cada três horas, pode fazer muito bem ao seu organismo. O ideal é comer pouco e várias vezes ao longo do dia. Isso mesmo! Ainda tem dúvidas? Então descubra abaixo por que você deve adotar as refeições fracionadas no seu dia a dia.

Tomar lanches entre as refeições é bom porque
[enriquece os acionistas da Sadia]
1- Pode ajudar a emagrecer: Um dos motivos é que comer de três em três horas acelera o metabolismo, pois a cada vez que você ingere alimentos, seu organismo queima calorias na tarefa da digestão. Por outro lado, quando se fica sem comer por muito tempo, o corpo aprende a economizar calorias. Funciona da seguinte maneira: o organismo, habituado a poucas refeições por dia, acostuma-se a acumular energia para os momentos de fome. Dessa forma, em períodos prolongados de jejum, o corpo "guarda” gordura extra para possíveis situações de escassez."
Bem, uma coisa está clara: comer lanches cada 3 horas faz muito bem à Sadia, que os vende. Mas e a CIÊNCIA, essa Geni da Nutrição, o que diz a respeito? Vejamos:

Neste estudo, os autores revisam as evidência epidemiológicas (sempre as epidemiológicas!) que deram origem à lenda urbana de que comer frequentemente ajudasse a perder peso, concluindo que são muito fracas. Quanto aos estudo experimentais, os autores concluem não haver suporte à essa ideia.

Neste estudo, os autores realizam um experimento em 30 voluntárias, às quais foi imposta uma dieta extremamente hipocalórica por 3 dias. Mas ao invés de IMAGINAR o que aconteceu com o metabolismo, os autores MEDIRAM a taxa metabólica basal. Resultado? Em 3 dias de restrição calórica severa, NÃO houve modificação da taxa metabólica basal. Tradução: restrição calórica aguda, mesmo severa, não "desacelera" o metabolismo.

Neste estudo, os 8 homens e 8 mulheres foram submetidos a jejum em dias alternados, ou seja, dieta normal em um dia, e JEJUM no outro dia, por 22 dias consecutivos. Segundo o senso comum nutricional, seu metabolismo deveria ficar muito mais lento com todo esse jejum, e mais lento ainda nos dias de jejum quando comparado aos dias de alimentação normal. Não foi o que aconteceu. A taxa metabólica em repouso não mudou do início ao fim do estudo, ou de dias alimentados para dias em jejum. Nem mesmo a temperatura do corpo mudou. Não estamos falando em pular UMA refeição, estamos falando em pular TODAS as refeições por 24 horas...

Em um estudo em que voluntários (homens e mulheres) foram submetidos a JEJUM de 12, 36 e 72 horas, e nos quais todo tipo de parâmetro fisiológico foi medido, foi observado um AUMENTO da taxa metabólica basal. Leia novamente, com calma. Essas pessoas não estavam comendo a cada 3 horas; estavam comendo a cada TRÊS DIAS! Ainda assim, o metabolismo basal não foi reduzido. Não. Ele AUMENTOU. Sinto um aroma de teoria refutada no ar...

Neste estudo, 10 voluntários do sexo masculino foram alimentados com comida suficiente para atingir suas necessidades calóricas diárias, e depois disso foram submetidos alternadamente a uma alimentação dividida em apenas duas refeições por dia ou dividida em SETE refeições por dia. O resultado? A frequência da alimentação NÃO afetou em NADA a taxa metabólica basal ou o gasto energético total dos indivíduos.

É nesse contexto que deve ser entendido este novo estudo, reportado pela imprensa como se fosse uma novidade, mas cujo resultado era, digamos, óbvio:

Fazer só duas refeições por dia pode ajudar no tratamento de diabetes tipo 2

Atualizado em  16 de maio, 2014 - 19:11 (Brasília) 22:11 GMT
Refeição (BBC)
Pacientes perderam mais peso e tiveram maior redução do nível de açúcar no sangue ao fazer duas refeições por dia
Comer apenas o café da manhã e o almoço pode ser uma forma mais efetiva de tratar a diabete tipo 2 do que fazer pequenas refeições ao longo do dia, dizem cientistas.
Pesquisadores do Instituto de Medicina Clínica e Experimental de praga testaram os dois métodos com dois grupos de 27 pessoas.
O segundo se alimentou com seis porções menores ao longo de todo o dia, como é frequentemente recomendado a pacientes com diabetes.O primeiro grupo fez duas refeições maiores por 12 semanas, comendo pela última vez até às 16 horas.
Depois, os grupos inverteram suas dietas. Em ambos os casos, todas as refeições do dia somavam 1.700 calorias.
Quando comeram duas vezes, os voluntários perderam mais peso e tiveram uma maior redução do nível de açúcar no sangue.
Segundo os cientistas, estes resultados corroboram com "evidências anteriores" de que refeições em menor número e porções maiores traziam mais benefícios.

(...)

"Os pacientes com menos refeições tinham medo de passar fome de noite, mas eles sentiram menos fome porque os deixamos comer até ficarem satisfeitos", diz a pesquisadora Hana Kahleova.
"Mas, quando comiam seis vezes ao dia, eles não ficavam satisfeitos. Isso foi surpreendente."
O pesquisador Richard Elliot, do instituto Diabetes UK, diz que o estudo reforça resultados de pesquisas anteriores que apontam para um novo tipo de dieta para este tipo de paciente.
"No entanto, antes será preciso realizar um estudo mais duradouro antes de mudar a indicação nutricional dada a pessoas com diabetes", disse Elliott.

Meu objetivo com essa postagem não é necessariamente indicar que as pessoas façam jejum ou comam apenas duas vezes por dia. Se você quiser e sentir fome, pode comer alimentos low carb / páleo diversas vezes por dia. O objetivo foi, na verdade, apenas o de destruir mais uma lenda urbana - a de que você PRECISA comer cada 3 horas. Só herbívoros precisam comer o tempo todo, dada a baixa densidade calórica de sua alimentação.
Repito aqui alguns pontos sobre os quais já escrevi na postagem sobre jejum:

  • Uma coisa é certa: nossos ancestrais não comiam 3 refeições todos os dias. Muito menos faziam lanches. Muito menos comiam a cada 3 horas, como mandam os nutricionistas;
  • O incrível é que, do ponto de vista evolutivo, isto é óbvio: quando estamos com fome, precisamos ter energia para ir à luta e caçar algum animal ou achar umas raízes - se desacelerássemos nosso metabolismo, nossa falta de comida só pioraria, e morreríamos. Isto é diferente da fome crônica, na qual desaceleramos para não morrer. Um leão é perigoso e ATIVO quando está com fome; quando está alimentado, ele dorme o dia inteiro;
  • Nas palavras de um paleontólogo citado por Robb Wolf, nossos ancestrais comiam tudo que podiam, quando podiam, e, de preferência, o pedaço de carne mais gorda que pudessem encontrar;
  • Só existem dois estados metabólicos possíveis: alimentado ("fed") ou "em jejum" ("fasted");
  • Enquanto estamos no estado alimentado, o corpo está no modo armazenamento; e no estado de jejum, usa as reservas;
  • Nossos antepassados mantinham um equilíbrio entre os dois estados;
  • No nosso estilo de vida atual, passamos no mínimo 2/3 do tempo no estado alimentado, comendo a cada 3 horas, o que impede o uso das reservas de gordura (óbvio, quando se para pra pensar);
  • A insulina é reduzida com low carb, mas nunca fica tão baixa quanto em jejum;
  • Alguns alimentos elevam muito pouco a insulina, mas nada BAIXA a insulina tanto quanto simplesmente não comer;
No fundo, estou convencido de que o motivo que levou os nutricionistas à essa insanidade (mandar pessoas com excesso de peso comer o tempo todo) foi uma constatação prática: a de que uma dieta de alto carboidrato leva as pessoas a sentir FOME o tempo todo (diferentemente de uma dieta low carb com mais proteína e gordura, que se caracteriza pela altíssima SACIEDADE). Assim, para que a pessoa possa manter uma dieta de alto carboidrato e baixa caloria, só mesmo comendo a cada 3 horas. Não foi uma orientação decorrente da ciência. Foi uma consequência de insistir em contrariar a ciência, a natureza e a evolução.

segunda-feira, 2 de junho de 2014

O livro mais importante da década

Há 7 anos, em 2007, era publicado o livro Good Calories, Bad Calories, de Gary Taubes. Em retrospecto e na minha opinião, este foi o mais importante livro sobre nutrição e saúde jamais escrito. Este livro, sozinho, com o peso de suas milhares de citações bibliográfica e de suas 600 páginas, mudou o equilíbrio do discurso nutricional nos anos que se seguiram. Se hoje pesquisadores famosos conseguem levar a hipótese alternativa aos periódicos científicos mais importantes do mundo, isso deve-se a esse JORNALISTA, Gary Taubes.

Pois é novamente de uma jornalista que vem o livro mais importante da década, The Big Fat Surprise.



Assim como os livros de Taubes, não se trata de um livro de dieta. Você não encontrará aqui receitas ou fases, alimentos proibidos ou permitidos. Não. Trata-se de uma magnífica narrativa sobre os fatos e pessoas que nos levaram a esta situação lamentável na qual nos encontramos, em que a diretrizes nutricionais estão de tal forma divorciadas do estado atual da ciência a ponto de sugerir que diabéticos consumam 60% de suas calorias na forma de glicose.

Aqui você encontrará as repostas para a pergunta: "se todas as evidências apontam para um sentido, por que todos os especialistas afirmam o contrário?"

O livro prende o leitor como se fosse uma obra de ficção. Nina consegue dar vida aos seus principais personagens e dar contexto histórico às suas ações e suas consequências.

O capítulo sobre a dieta mediterrânea é especialmente fascinante e exemplifica, ao meu ver, como determinados conceitos emanados da cabeça de uma ou duas personalidades fortes podem tornar-se completamente hegemônicas e virais.

O livro está tendo uma tremenda repercussão nos EUA - o que é bom, muito bom!  Veja alguns exemplos:


Quando Gary Taubes lançou Good Calories, Bad Calories, o mundo foi pego de surpresa. A ideia de que a gordura faz mal (e, por conseguinte, de que deveríamos basear nossa alimentação em amido) era algo esculpido em pedra, com status de dogma. Taubes provocou as primeiras rachaduras neste consenso monolítico. Hoje, embora ainda permaneça grande e pesado, o consenso está desmoronando a olhos vistos.

O livro de Nina Teicholz chega em outro contexto histórico. O mundo não estava preparado para Taubes - eram tempos sombrios. Mas o momento não poderia ser melhor para Nina. Para exemplificar o que quero dizer, reveja o tom destas manchetes recentes, inimagináveis há 7 anos: 
Comidas "low fat" estão cheias de níveis "danosos" de açúcar,
EUA propõem novos rótulos que 'aceitam' gordura e 'demonizam' açúcar, Gordura saturada não é a vilã para o coração, diz estudo,  Uma dieta de baixa gordura saturada não reduz o risco cardiovascular nem lhe ajuda a viver mais, Carboidratos e a glicose são prejudiciais para a saúde do cérebro.

Sei que a década não acabou. Mas, até o momento, esse é o livro da década.

P.S.: conversei com a autora, que já submeteu o livro a várias editoras nacionais. Ou seja, há planos para a sua tradução. Se você tem ligações junto à área editorial, entre em contato comigo.