I suspect that it is our attitude about obesity that may also put us at risk. Cross-cultural studies suggest that larger people are not subject to the same diseases in countries where there is less stigma attached to weight.
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Also, in the United States, there is a stronger relationship between BMI and morbidity (disease) and mortality (early death) among groups more negatively affected by body image concerns (younger people, Caucasians, and women).
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Even more telling, when researchers looked at a nationally representative group of more than 170,000 U.S. adults, they found the difference between actual weight and perceived ideal weight was a better indicator of mental and physical health than BMI.
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In other words,
feeling
fat has stronger health effects than
being
fat.
This finding is not surprising given the well established relationship between stigma and stress, which in turn increases disease risk.
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And of course, weight discrimination is pervasive and severe—so severe that its prevalence now equals or surpasses discrimination based on race or gender.
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Take a closer look at the four most common conditions that have been blamed on weight: hypertension, atherosclerosis, type 2 diabetes, and cancer. The data present a very different picture than is commonly portrayed.
Obesity and Hypertension
Hypertension refers to high blood pressure, a condition that is two to three times more common among obese people than lean people.
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To what extent this is caused by fat, however, is unclear. It may have more to do with the weight cycling that results from trying to control weight than the actual weight itself.
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One study showed that obese women who had dieted had high blood pressure, while those who had never been on a diet had normal blood pressure.
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Rat studies also show that obese rats that have weight cycled have very high blood pressures compared to obese rats that have not weight cycled.
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This finding could also explain the weak association between obesity and hypertension in cultures where dieting is uncommon.
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Since admonitions to lose weight typically result in weight cycling, the proposed “cure” for hypertension may actually be its cause.
Also, it is well documented that obese people with hypertension live significantly longer than thinner people with hypertension
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and have a lower risk of heart attack, stroke, or early death.
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Rather than identifying health risk, as it does in thinner people, hypertension in fatter people may simply be a requirement for pumping blood through their larger bodies.
Does weight loss reduce hypertension? Many studies document that blood pressure improves during weight loss in hypertensive people. However, the long-term results are disappointing, even when the weight loss is maintained—including massive amounts of weight loss after bariatric surgery.
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Studies that demonstrate weight loss through various interventions, such as exercise, sodium reduction, and stress management, show promising short-term effects on blood pressure. However, it is unclear whether the weight loss itself brings about this improvement. For instance, studies document that when weight loss is achieved, the reduction in blood pressure parallels a reduction in dietary sodium, suggesting that dietary change is actually the mitigating factor.
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The well-known DASH (Dietary Approaches to Stop Hypertension) diet, which is a reduced sodium diet, has been shown to lower blood pressure successfully, even without lowering weight.
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It is also interesting to note that the prevalence of high blood pressure dropped by half between 1960 and 2000, declining much more steeply among those deemed overweight and obese than among thinner individuals.
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(To what extent this is the result of improved medical care or medication is unclear.)
Given this evidence, why is the standard advice given to people with high blood pressure to lose weight?
Obesity and Atherosclerosis
Atherosclerosis refers to the buildup of cholesterol-laden plaque on artery walls that narrows the passage, restricting blood flow. Because atherosclerosis makes the heart work harder, it can damage the heart.
Since obese people have more fat on their bodies, they must have more fat in their arteries, right? Yet research doesn’t support this. Five decades of autopsy studies consistently show no relationship between body fat and atherosclerosis.
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Ultrasound studies corroborate this,
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and well over half of the angiographic studies conducted between 1976 and 2000 show obesity has no relationship to either the presence of atherosclerosis or its progression over time.
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The largest, most comprehensive angiographic study examined 4,500 angiograms and concluded that every eleven-pound
increase
in weight was associated with a 10 to 40 percent
lower
chance of atherosclerosis.
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In other words, fat men and women had the cleanest arteries!
Furthermore, research frequently indicates that overweight and obese adults with atherosclerosis (like those with high blood pressure, as discussed earlier) have a lower risk of heart attack, stroke, or early death, compared with their normal-weight counterparts.
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The famous Framingham Heart Study followed a cohort of men for more than thirty years and found that the men who had gained weight were less likely to have developed heart disease or to have died from heart disease.
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It is interesting to note that the incidence of heart disease has dropped dramatically in the time since obesity rates started to rise and is now occurring much later in life.
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Heart disease death rates have been falling for more than five decades, including an impressive 22.1 percent drop just between 1993 and 2003. Research indicates that improved medical care is only part of the explanation.
Given the preponderance of evidence, why advise people to lose weight in order to prevent or treat atherosclerosis?
Obesity and Type 2 Diabetes
Type 2 diabetes is a metabolic disorder in which people have a reduced sensitivity to insulin. Insulin helps certain nutrients, such as glucose, get into cells, and when insulin doesn’t work effectively, cells don’t get the energy they need to work effectively.
Type 2 diabetes is much more common among obese individuals than leaner individuals (80 percent of people with type 2 diabetes are obese),
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and thus diabetes is commonly blamed on weight. However, it is clear that risk of type 2 diabetes includes a genetic component, and there is strong evidence to support the idea that the genes that play a role in causing diabetes also cause weight gain.
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The “thrifty genotype” theory was first proposed in the 1960s and has gained increasing acceptance ever since.
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The insulin resistance that is characteristic of type 2 diabetes could be viewed as a helpful genetic adaptation to the cycles of famine common in history. Insulin resistance supports efficient storage of fat when food is available and slows energy usage when food is less available, which would have contributed to longevity in earlier times. Our ancestors didn’t have fast-food caves on every corner, nor could they dip into their refrigerator/freezers for an always available supply of preserved food.
Research shows that high levels of insulin appear
before
weight gain in future diabetics.
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The mechanism looks like this: Insulin resistance develops first. Because the cells are partially resistant to the insulin, glucose and other nutrients can’t get into most cells, despite the cells’ increasing need for the nutrients. The pancreas pumps out even more insulin to try to accommodate the cells’ need for energy. The high insulin levels increase insulin resistance and stimulate appetite. Because fat cells are less likely than other cells to develop insulin resistance, the high insulin levels readily allow fat storage, resulting in weight gain. As this cycle continues, the insulin resistance takes on a new name: diabetes. In other words, weight gain is actually an early symptom of type 2 diabetes.
This is not to suggest that body fat is entirely benign in the type 2 diabetes disease process. But the relationship between type 2 diabetes and body fat appears to be self-perpetuating: The high levels of insulin characteristic of type 2 diabetes lead to weight gain, and high levels of abdominal fat increase insulin resistance, worsening type 2 diabetes.
On a short-term basis, weight loss is very effective at improving control of blood glucose. However, this doesn’t mean that the diabetes is being cured; even skipping one meal will similarly lower blood glucose. A 1995 review of all of the controlled weight-loss studies for type 2 diabetics showed that the initial improvements were followed by a deterioration back to starting values six to eighteen months after treatment,
even when the weight loss was maintained
.
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Surgical studies allow us to see the effects of weight loss without changing other factors like eating or activity habits. Gastric bypass surgery appears to reverse diabetes within days, before significant weight is lost, which suggests that it is not the weight loss that brings about the improvement but some other factor (such as a change in the release of gut hormones).
Liposuction studies provide further support that it is not the weight itself that is problematic. For example, in one study researchers examined obese women, half of whom were diabetic, before and ten to twelve weeks after an average of about twenty pounds of body fat was removed.
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Despite the weight loss, their metabolic profiles did not improve, including their fasting glucose and insulin levels and their insulin sensitivity.
Though body fat is certainly a contributor to type 2 diabetes—no doubt it’s the strongest card the obesity alarmists hold—numerous research studies document that type 2 diabetes can be improved or reversed through changes in nutrition or activity habits,
even when little or no weight is lost
.
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Eating better and becoming more active are much more effective for curing, preventing, or controlling diabetes than shedding pounds.
It is also interesting to note that obese persons with type 2 diabetes live longer than thinner people with the condition, suggesting that diabetes, like hypertension, may actually be less problematic in a larger body.
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Given this evidence, why is the first suggestion to people with diabetes that they lose weight? Why not encourage improving lifestyle habits—a strategy which has actually proven effective?
Obesity and Cancer
What about the headlines proclaiming that fat gives you cancer? One report, from the American Institute for Cancer Research (AICR), was all over the media claiming that overweight and obesity increases risk for six cancers: pancreas, kidney, endometrium, breast, colorectum, and esophagus.
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All that was lacking in this very comprehensive, 517-page report was convincing evidence to support these claims!
Take a look at the evidence they present for pancreatic cancer. Their researchers found that of the twenty-three cohort studies
h
they deemed well-designed, only four showed a statistically significant association between obesity and pancreatic cancer. I had the opportunity to discuss this with a representative of the AICR on the BBC World Report radio program,
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and when I asked him to explain how this data justified their claims, his defense was that they also examined case-control studies.
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He’s right. Here’s what his researchers found: Of the fifteen case-control studies
i
, only one showed a statistically significant increased risk—and one showed a statistically significant
decreased
risk.
Breast cancer? Of the twenty-six cohort studies discussed in the report, only three showed a significant association, while two showed a
decreased
risk of breast cancer for the obese!