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Old 03-02-2006, 04:27 AM   #1
olivefun
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Default New york times article about low fat diets and possible reduced health risks

February 8, 2006
Low-Fat Diet Does Not Cut Health Risks, Study Finds
http://www.nytimes.com/2006/02/08/he...7&nl=ep&emc=ep

By GINA KOLATA
Correction Appended
The largest study ever to ask whether a low-fat diet reduces the risk of getting cancer or heart disease has found that the diet has no effect.

The $415 million federal study involved nearly 49,000 women ages 50 to 79 who were followed for eight years. In the end, those assigned to a low-fat diet had the same rates of breast cancer, colon cancer, heart attacks and strokes as those who ate whatever they pleased, researchers are reporting today.

"These studies are revolutionary," said Dr. Jules Hirsch, physician in chief emeritus at Rockefeller University in New York City, who has spent a lifetime studying the effects of diets on weight and health. "They should put a stop to this era of thinking that we have all the information we need to change the whole national diet and make everybody healthy."

The study, published in today's issue of The Journal of the American Medical Association, was not just an ordinary study, said Dr. Michael Thun, who directs epidemiological research for the American Cancer Society. It was so large and so expensive, Dr. Thun said, that it was "the Rolls-Royce of studies." As such, he added, it is likely to be the final word.

"We usually have only one shot at a very large-scale trial on a particular issue," he said.

The results, the study investigators agreed, do not justify recommending low-fat diets to the public to reduce their heart disease and cancer risk. Given the lack of benefit found in the study, many medical researchers said that the best dietary advice, for now, was to follow federal guidelines for healthy eating, with less saturated and trans fats, more grains, and more fruits and vegetables.

Not everyone was convinced. Some, like Dr. Dean Ornish, a longtime promoter of low-fat diets and president of the Preventive Medicine Research Institute in Sausalito, Calif., said that the women did not reduce their fat to low enough levels or eat enough fruits and vegetables, and that the study, even at eight years, did not give the diets enough time.

Others said that diet could still make a difference, at least with heart disease, if people were to eat the so-called Mediterranean diet, low in saturated fats like butter and high in oils like olive oil. The women in the study reduced all kinds of fat.

The diets studied "had an antique patina," said Dr. Peter Libby, a cardiologist and professor at Harvard Medical School. These days, Dr. Libby said, most people have moved on from the idea of controlling total fat to the idea that people should eat different kinds of fat.

But the Mediterranean diet has not been subjected to a study of this scope, researchers said.

And Barbara V. Howard, an epidemiologist at MedStar Research Institute, a nonprofit hospital group, and a principle investigator in the study, said people should realize that diet alone was not enough to stay healthy.

"We are not going to reverse any of the chronic diseases in this country by changing the composition of the diet," Dr. Howard said. "People are always thinking it's what they ate. They are not looking at how much they ate or that they smoke or that they are sedentary."

Except for not smoking, the advice for a healthy lifestyle is based largely on indirect evidence, Dr. Howard said, but most medical researchers agree that it makes sense to eat well, control weight and get regular exercise.

That is also what the cancer society recommends. Dr. Thun, who described the study's results as "completely null over the eight-year follow-up for both cancers and heart disease," said his group had no plans to suggest that low-fat diets were going to protect against cancer.

Others cautioned against being too certain that a particular diet would markedly improve health, and said that whether someone developed a chronic disease might not be entirely under their control — genetics also plays a role.

David A. Freedman, a statistician at the University of California, Berkeley, who is not connected with the study but has written books on the design and analysis of clinical trials, said the results should be taken seriously.

"The studies were well designed," Dr. Freedman said, "and the investigators tried to confirm popular hypotheses about the protective effect of diet against three major diseases in women."

"But," he added, "the diet studied here turned out not to be protective after all."

The study was part of the Women's Health Initiative of the National Institutes of Health, the same program that showed that hormone therapy after menopause might have more risks than benefits.

In this case, the study addressed a tricky problem. For decades, many scientists have said, and many members of the public have believed, that what people eat — the composition of the diet — determines how likely they are to get a chronic disease. But that has been hard to prove. Studies of dietary fiber and colon cancer failed to find that fiber was protective, and studies of vitamins thought to protect against cancer failed to show an effect.

Many cancer researchers have questioned large parts of the diet-cancer hypothesis, but it has kept a hold on the public imagination. "Nothing fascinates the American public so much as the notion that what you eat rather than how much you eat affects your health," said Dr. Libby, the Harvard professor.

The study found that women who were randomly assigned to follow a low-fat diet ate significantly less fat over the next eight years. But they had just as much breast and colon cancer and just as much heart disease. The women were not trying to lose weight, and their weights remained fairly steady. But their experiences with the diets allowed researchers to question some popular notions about diet and obesity.

There is a common belief that Americans get fat because they eat too many carbohydrates. The idea is that a high-carbohydrate, low-fat diet leads to weight gain, higher insulin and blood glucose levels, and more diabetes, even if the calories are the same as in a higher-fat diet. That did not happen here.

Others have said the opposite: that low-fat diets enable people to lose weight naturally. But that belief was not supported by this study.

As for heart disease risk factors, the only one affected was LDL cholesterol, which increases heart disease risk. The levels were slightly higher in women eating the higher-fat diet, but not high enough to make a noticeable difference in their risk of heart disease.

Although all the study participants were women, the colon cancer and heart disease results should also apply to men, said Dr. Jacques Rossouw, the project officer for the Women's Health Initiative.

Dr. Rossouw said the observational studies that led to the hypothesis about colon cancer and dietary fat included men and women. With heart disease, he said, researchers have found that women and men respond in the same way to dietary fat.

The most recent study follows a smaller one, reported last year, on low-fat diets for women who had breast cancer. That study hinted that eating less fat might help prevent a recurrence. But the current study, asking if a low-fat diet could protect women from breast cancer in the first place, had findings that fell short of statistical significance, meaning they could have occurred by chance.

Dr. Rossouw said he was still intrigued by the breast cancer data, even though it was not statistically significant. The women on low-fat diets had a 9 percent lower rate of breast cancer; the incidence was 42 per 10,000 per year in women in the low-fat diet group, compared with 45 per 10,000 per year in women consuming their regular diet.

That could mean that fat in the diet may have a small effect, Dr. Rossouw said, perhaps in some subgroups of women or over a longer period of time. He added that the study investigators would continue to follow the women to see if the effect became more pronounced.

While cancer researchers said they were disappointed by the results, heart disease researchers said they were not surprised that simply reducing total fat had no effect, because they had moved on from that hypothesis.

Of course, Dr. Libby acknowledged, the latest advice, to follow a Mediterranean diet and get regular exercise, has never been tested in a large randomized clinical trial. "If they did a study like that and it was negative," he said, "then I'd have to give up my cherished hypotheses for data."

The low-fat diet was not easy to follow, said Dr. Rowan T. Chlebowski, a medical oncologist at Harbor-U.C.L.A. Medical Center and one of the study's principal investigators. Women were told to aim for a diet that had just 20 percent of its calories as fat, and most fell short.

The diet they were told to follow "is different than the way most people eat," Dr. Chlebowski said. It meant, for example, no butter on bread, no cream cheese on bagels, no oil in salad dressings.

"If a physician told a patient to eat less fat, that will do nothing," he said. "If you send someone to a dietitian one time, that will do next to nothing." The women in the study had 18 sessions in small groups with a trained nutritionist in the first year and four sessions a year after that.

In the first year, the women on the low-fat diets reduced the percentage of fat in their diet to 24 percent of daily calories, and by the end of the study their diets had 29 percent of their calories as fat. In the first year, the women in the control group were eating 35 percent of their calories as fat, and by the end of the study their dietary fat content was 37 percent. The two groups consumed about the same number of calories.

Some medical specialists emphasized that the study did not mean people should abandon low-fat diets.

"What we are saying is that a modest reduction of fat and a substitution with fruits and vegetables did not do anything for heart disease and stroke or breast cancer or colorectal cancer," said Dr. Nanette K. Wenger, a cardiologist and professor of medicine at Emory University School of Medicine in Atlanta. "It doesn't say that this diet is not beneficial."

But Dr. Freedman, the Berkeley statistician, said the overall lesson was clear.

"We, in the scientific community, often give strong advice based on flimsy evidence," he said. "That's why we have to do experiments."

Correction: Feb. 16, 2006
A front-page article on Feb. 8 about a new study finding that low-fat diets have no effect on the risk of cancer or heart disease misstated the incidence of breast cancer among women in the study. It was 42 per 10,000 per year in women in the low-fat-diet group, compared with 45 per 10,000 in women consuming their regular diet — not per 1,000. (The difference was deemed statistically insignificant.)
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Old 05-16-2007, 04:41 AM   #2
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Default More Studies by Jules Hirsch

http://www.nytimes.com/2007/05/08/he...410684&ei=5070

Quote:
It was 1959. Jules Hirsch, a research physician at Rockefeller University, had gotten curious about weight loss in the obese. He was about to start a simple experiment that would change forever the way scientists think about fat.

Obese people, he knew, had huge fat cells, stuffed with glistening yellow fat. What happened to those cells when people lost weight, he wondered. Did they shrink or did they go away? He decided to find out.

It seemed straightforward. Dr. Hirsch found eight people who had been fat since childhood or adolescence and who agreed to live at the Rockefeller University Hospital for eight months while scientists would control their diets, make them lose weight and then examine their fat cells.

The study was rigorous and demanding. It began with an agonizing four weeks of a maintenance diet that assessed the subjects’ metabolism and caloric needs. Then the diet began. The only food permitted was a liquid formula providing 600 calories a day, a regimen that guaranteed they would lose weight. Finally, the subjects spent another four weeks on a diet that maintained them at their new weights, 100 pounds lower than their initial weights, on average.

Dr. Hirsch answered his original question — the subjects’ fat cells had shrunk and were now normal in size. And everyone, including Dr. Hirsch, assumed that the subjects would leave the hospital permanently thinner.

That did not happen. Instead, Dr. Hirsch says, “they all regained.” He was horrified. The study subjects certainly wanted to be thin, so what went wrong? Maybe, he thought, they had some deep-seated psychological need to be fat.

So Dr. Hirsch and his colleagues, including Dr. Rudolph L. Leibel, who is now at Columbia University, repeated the experiment and repeated it again. Every time the result was the same. The weight, so painstakingly lost, came right back. But since this was a research study, the investigators were also measuring metabolic changes, psychiatric conditions, body temperature and pulse. And that led them to a surprising conclusion: fat people who lost large amounts of weight might look like someone who was never fat, but they were very different. In fact, by every metabolic measurement, they seemed like people who were starving.

Before the diet began, the fat subjects’ metabolism was normal — the number of calories burned per square meter of body surface was no different from that of people who had never been fat. But when they lost weight, they were burning as much as 24 percent fewer calories per square meter of their surface area than the calories consumed by those who were naturally thin.

The Rockefeller subjects also had a psychiatric syndrome, called semi-starvation neurosis, which had been noticed before in people of normal weight who had been starved. They dreamed of food, they fantasized about food or about breaking their diet. They were anxious and depressed; some had thoughts of suicide. They secreted food in their rooms. And they binged.

The Rockefeller researchers explained their observations in one of their papers: “It is entirely possible that weight reduction, instead of resulting in a normal state for obese patients, results in an abnormal state resembling that of starved nonobese individuals.”

Eventually, more than 50 people lived at the hospital and lost weight, and every one had physical and psychological signs of starvation. There were a very few who did not get fat again, but they made staying thin their life’s work, becoming Weight Watchers lecturers, for example, and, always, counting calories and maintaining themselves in a permanent state of starvation.

“Did those who stayed thin simply have more willpower?” Dr. Hirsch asked. “In a funny way, they did.”

One way to interpret Dr. Hirsch and Dr. Leibel’s studies would be to propose that once a person got fat, the body would adjust, making it hopeless to lose weight and keep it off. The issue was important, because if getting fat was the problem, there might be a solution to the obesity epidemic: convince people that any weight gain was a step toward an irreversible condition that they most definitely did not want to have.

But another group of studies showed that that hypothesis, too, was wrong.

It began with studies that were the inspiration of Dr. Ethan Sims at the University of Vermont, who asked what would happen if thin people who had never had a weight problem deliberately got fat.

His subjects were prisoners at a nearby state prison who volunteered to gain weight. With great difficulty, they succeeded, increasing their weight by 20 percent to 25 percent. But it took them four to six months, eating as much as they could every day. Some consumed 10,000 calories a day, an amount so incredible that it would be hard to believe, were it not for the fact that there were attendants present at each meal who dutifully recorded everything the men ate.

Once the men were fat, their metabolisms increased by 50 percent. They needed more than 2,700 calories per square meter of their body surface to stay fat but needed just 1,800 calories per square meter to maintain their normal weight.

When the study ended, the prisoners had no trouble losing weight. Within months, they were back to normal and effortlessly stayed there. The implications were clear. There is a reason that fat people cannot stay thin after they diet and that thin people cannot stay fat when they force themselves to gain weight. The body’s metabolism speeds up or slows down to keep weight within a narrow range. Gain weight and the metabolism can as much as double; lose weight and it can slow to half its original speed.

That, of course, was contrary to what every scientist had thought, and Dr. Sims knew it, as did Dr. Hirsch.

The message never really got out to the nation’s dieters, but a few research scientists were intrigued and asked the next question about body weight: Is body weight inherited, or is obesity more of an inadvertent, almost unconscious response to a society where food is cheap, abundant and tempting? An extra 100 calories a day will pile on 10 pounds in a year, public health messages often say. In five years, that is 50 pounds.

The assumption was that environment determined weight, but Dr. Albert Stunkard of the University of Pennsylvania wondered if that was true and, if so, to what extent. It was the early 1980s, long before obesity became what one social scientist called a moral panic, but a time when those questions of nature versus nurture were very much on Dr. Stunkard’s mind.

He found the perfect tool for investigating the nature-nurture question — a Danish registry of adoptees developed to understand whether schizophrenia was inherited. It included meticulous medical records of every Danish adoption between 1927 and 1947, including the names of the adoptees’ biological parents, and the heights and weights of the adoptees, their biological parents and their adoptive parents.

Dr. Stunkard ended up with 540 adults whose average age was 40. They had been adopted when they were very young — 55 percent had been adopted in the first month of life and 90 percent were adopted in the first year of life. His conclusions, published in The New England Journal of Medicine in 1986, were unequivocal. The adoptees were as fat as their biological parents, and how fat they were had no relation to how fat their adoptive parents were.

The scientists summarized it in their paper: “The two major findings of this study were that there was a clear relation between the body-mass index of biologic parents and the weight class of adoptees, suggesting that genetic influences are important determinants of body fatness; and that there was no relation between the body-mass index of adoptive parents and the weight class of adoptees, suggesting that childhood family environment alone has little or no effect.”

In other words, being fat was an inherited condition.

Dr. Stunkard also pointed out the implications: “Current efforts to prevent obesity are directed toward all children (and their parents) almost indiscriminately. Yet if family environment alone has no role in obesity, efforts now directed toward persons with little genetic risk of the disorder could be refocused on the smaller number who are more vulnerable. Such persons can already be identified with some assurance: 80 percent of the offspring of two obese parents become obese, as compared with no more than 14 percent of the offspring of two parents of normal weight.”

A few years later, in 1990, Dr. Stunkard published another study in The New England Journal of Medicine, using another classic method of geneticists: investigating twins. This time, he used the Swedish Twin Registry, studying its 93 pairs of identical twins who were reared apart, 154 pairs of identical twins who were reared together, 218 pairs of fraternal twins who were reared apart, and 208 pairs of fraternal twins who were reared together.

The identical twins had nearly identical body mass indexes, whether they had been reared apart or together. There was more variation in the body mass indexes of the fraternal twins, who, like any siblings, share some, but not all, genes.

The researchers concluded that 70 percent of the variation in peoples’ weights may be accounted for by inheritance, a figure that means that weight is more strongly inherited than nearly any other condition, including mental illness, breast cancer or heart disease.

The results did not mean that people are completely helpless to control their weight, Dr. Stunkard said. But, he said, it did mean that those who tend to be fat will have to constantly battle their genetic inheritance if they want to reach and maintain a significantly lower weight.

The findings also provided evidence for a phenomenon that scientists like Dr. Hirsch and Dr. Leibel were certain was true — each person has a comfortable weight range to which the body gravitates. The range might span 10 or 20 pounds: someone might be able to weigh 120 to 140 pounds without too much effort. Going much above or much below the natural weight range is difficult, however; the body resists by increasing or decreasing the appetite and changing the metabolism to push the weight back to the range it seeks.

The message is so at odds with the popular conception of weight loss — the mantra that all a person has to do is eat less and exercise more — that Dr. Jeffrey Friedman, an obesity researcher at the Rockefeller University, tried to come up with an analogy that would convey what science has found about the powerful biological controls over body weight.

He published it in the journal Science in 2003 and still cites it:

“Those who doubt the power of basic drives, however, might note that although one can hold one’s breath, this conscious act is soon overcome by the compulsion to breathe,” Dr. Friedman wrote. “The feeling of hunger is intense and, if not as potent as the drive to breathe, is probably no less powerful than the drive to drink when one is thirsty. This is the feeling the obese must resist after they have lost a significant amount of weight.”

This is an excerpt from Gina Kolata’s new book, “Rethinking Thin: The New Science of Weight Loss — and the Myths and Realities of Dieting” (Farrar, Straus & Giroux).

Correction: May 12, 2007

An article in Science Times on Tuesday about the role of genes in weight gain misstated the publication date for an article in the journal Science describing the biological controls over body weight. The article was published in 2003, not 2000.
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Old 05-16-2007, 01:42 PM   #3
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Default Thanks for posting

I wasn't able to get the NYT and wanted to read it, so thanks for posting it. What frustrates me though, it no one seems to be talking about the even bigger picture. The more diverse a species, the better its chance of survival. And we evolve for the survival of the species, not the maximum longevity of the individual. Biologists tell us the individual is nothing in evolution. I don't buy that all fat people have shorter life spans, but even if they did, it doesn't mean fatness is not natural. Mother Nature doesn't care if every single person lives the exact same amount of time. In fact, there has never been a time when that was so. Mother Nature cares about having a population varied enough to survive different threats. Fat people survive some conditions better, thin people others. We have no idea what is coming down the pike and who will be at biological advantage. It is so sad we can't accept body diversity as nature's plan and quit defining fatness as a problem.

"Weight obsession is a social disease. If we cared more about CO2 than BMI there would still be time."
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