The thin evidence that losing weight makes you healthier 2

The Weight of the Evidence

It’s time to stop telling fat people to become thin. 

(Continued from Page 1)

While concerns over appearance motivate a lot of would-be dieters, concerns about health fuel the national conversation about the “obesity epidemic.” So how bad is it, health-wise, to be overweight or obese? The answer depends in part on what you mean by “health.” Right now, we know obesity is linked with certain diseases, most strongly type 2 diabetes, but as scientists are fond of saying, correlation does not equal causation. Maybe weight gain is an early symptom of type 2 diabetes. Maybe some underlying mechanism causes both weight gain and diabetes. Maybe weight gain causes diabetes in some people but not others. People who lose weight often see their blood sugar improve, but that’s likely an effect of calorie reduction rather than weight loss. Type 2 diabetics who have bariatric surgery go into complete remission after only seven days, long before they lose much weight, because they’re eating only a few hundred calories a day.

Disease is also attributed to what we eat (or don’t), and here, too, the connections are often assumed to relate to weight. For instance, eating fast food once a week has been linked to high blood pressure, especially for teens. And eating fruits and vegetables every day is associated with lower risk of heart disease. But it’s a mistake to simply assume weight is the mechanism linking food and disease. We have yet to fully untangle the relationship.

Higher BMIs have been linked to a higher risk of developing type 2 diabetes, heart disease, and certain cancers, especially esophageal, pancreatic, and breast cancers. But weight loss is not necessarily linked to lower levels of disease. The only study to follow subjects for more than five years, the 2013 Look AHEAD study, found that people with type 2 diabetes who lost weight had just as many heart attacks, strokes, and deaths as those who didn’t.

Not only that, since 2002, study after study has turned up what researchers call the “obesity paradox”: Obese patients with heart disease, heart failure, diabetes, kidney disease, pneumonia, and many other chronic diseases fare better and live longer than those of normal weight.

Likewise, we don’t fully understand the relationship between weight and overall mortality. Many of us assume it’s a linear relationship, meaning the higher your BMI, the higher your risk of early death. But Katherine Flegal, an epidemiologist with the CDC, has consistently found a J-shaped curve, with the highest death rates among those at either end of the BMI spectrum and the lowest rates in the “overweight” and “mildly obese” categories.

Study after study has turned up the “obesity paradox”: Obese patients with disease live longer than those of normal weight. 

None of this stops doctors and researchers from recommending weight loss for health reasons. Donna Ryan, professor emeritus at the Pennington Biomedical Research Center in Baton Rouge, co-chaired the National Institutes of Health panel that recently developed new guidelines for treating obesity, including calorie-restricted diets and commercial diet programs. “Those who have a BMI of 30 and up need treatment, no questions asked,” they wrote. I asked Ryan why, given that so few people keep weightoff and given the risks of yo-yo dieting, the committee backed the same old ineffective treatments. “I’m not familiar with any of the research that says yo-yoing is bad for you,” Ryan told me. “I’m not convinced there’s any harm whatsoever in losing and regaining weight.”

Why do doctors keep prescribing treatments that don’t work for a condition that’s often benign? I suspect one reason lies in the fanaticism that often seems to drive the public debate around weight. Last January, for instance, when Flegal’s meta-analysis showing a low risk of death for overweight people hit the news, one of its most vocal critics was Walter Willett, an epidemiologist at the Harvard School of Public Health. He told a reporter from NPR, “This study is really a pile of rubbish, and no one should waste their time reading it.” A month later, Willett organized a symposium at Harvardjust to attack Flegal’s findings.

Willett’s career, like countless others’, has been built on the obesity-will-kill-you paradigm. Tam Fry, a spokesperson for the National Obesity Forum in the U.K., also dissed Flegal’s work. “This is a horrific message to put out,” he told the BBC. “We shouldn’t take it for granted that we can cancel the gym, that we can eat ourselves to death with black forest gateaux.”

Actually, Flegal’s findings suggest nothing of the kind. But Willett, Fry, and others seem to see them as a dangerous challenge to a fundamental truth. UCLA sociologist Abigail Saguy, author of What’s Wrong With Fat?, says people are often invested in their own thin privilege. “They want to think they’ve earned it by working hard and counting calories, and they cling to it,” she says.

There’s a lot of money at stake in treating obesity. The American Medical Association—against the recommendations of its own Committee on Science and Public Health—recently classified obesity as a disease, and doctors hope insurers will start covering more treatments for obesity. If Medicare goes along with the AMA and designates obesity as a disease, doctors who discuss weight with their patients will be able to add that diagnosis code to their bill, and charge more for the visit.

Obesity researchers and doctors also defend what appear to be financial conflicts of interest. In 2013, the New England Journal of Medicine published “Myths, Presumptions, and Facts About Obesity.” The authors dismissed the often-observed link between weight cycling and mortality, saying it was “probably due to confounding by health status” (code for “We just can’t believe this could be true”) and went on to plug meal replacements like Jenny Craig, medications, and bariatric surgery.

Five of the 20 authors disclosed financial support from sponsors in related industries, including UAB’s David Allison. I asked him how he would respond to allegations of financial self-interest. “It would be no different than anybody saying about any other person who puts forth an idea, ‘I want to comment that you have this background or personality, this sexual orientation, weight, gender, or race,’ ” he argued. “These conflicts were disclosed, we didn’t hide them, we weren’t ashamed of them. And what’s your point?”

Another layer to the onion may lie in our deeply held cultural assumptions around weight. “People, journalists, and researchers live in a world where it’s taken for granted that fat is bad and thin is good,” says Saguy.

Doctors buy into those assumptions and biases even more heavily than the rest of us, which may explain in part why they continue to blame patients who can’t keep weight off. Joseph Majdan, a cardiologist who teaches at Jefferson Medical College in Philadelphia, has lost and regained the same 100 or so pounds more times than he can count. Some of the meanest comments Majdan has heard about his weight have come from other doctors, like the med-school classmate who asked if she could project slides onto a pair of his white intern’s pants for a skit. Or the colleague who asked him, “Aren’t you disgusted with yourself?”

Source: www.slate.com