Obesity Paradox: Where the Fat Settles—Not Weight—Matters Most in Diabetes

with Edward J. Boyko, MD, MPH, and Wei Bao, MD, PhD

Scientists and doctors call it the obesity paradox—the idea that while obesity may increase the risks of developing heart disease and diabetes for most people, it might actually be protective, offering the possibility of longer survival, in a few lucky individuals.1

Certainly, if you're among the throngs of people struggling to deal with a higher than recommended body weight, the idea that maybe, just maybe, you are probably hoping to be one of those lucky few who doesn’t need to be concerned.

Alas, the problem is that the obesity paradox is not so much a puzzle as it is more likely a myth for most of us.

Best to rely on waist circumference as a predictor of disease risk over BMI.Abdominal fat has a more direct impact on risk of diabetes and heart disease, even longevity, than body weight or BMI. Photo: 123rf

Can a High BMI Be Ignored—the Obesity Paradox—Even If You Have Diabetes?

The question of whether the obesity paradox holds true for those with type 2 diabetes (T2D) is especially important, since link between overweight and the development of diabetes and heart disease is well-established.1 This concern becomes more pressing when your fat settles around the waist, increasing your risk of heart problems.2

In a recent intensive review of the research,3 investigators confirmed that the obesity paradox doesn't hold water for most everyone with type 2 diabetes. In addition, the higher your level of body fat, the greater the likelihood that you will develop diabetes, if you haven’t already, and that other chronic conditions will follow in due course.

Body fat, in simple terms, poses a real danger to your health, and anyone who tries to convince that you are safe from disease isn’t doing you any favors. Take the findings from another recent study—the authors show that when fat settles around the organs (so-called visceral fat)—it is dangerous enough to reduce your longevity even if you're weight is in the healthy range.3

This type of abdomenal fat, also known as central obesity, has long been known as the riskiest form of overweight. In fact, a bigger waist circumference is likely to shorten your lifespan by about 14 years.2-4

Parsing Out the Reality from the Research 

Edward J. Boyko, MD, MPH, an internist and professor of medicine at the University of Washington School of Medicine in Seattle, has studied the obesity paradox intensely, including how it may apply to those with type 2 diabetes.

With his colleague, Seung Jin Han, MD, PhD, in the department of endocrinology and metabolism at Ajou University School of Medicine in Suwon, Korea, Dr. Boyko reviewed the results from numerous studies that looked at the association between obesity and death rates among individuals with type 2 diabetes.1

Some studies show a lower risk of early death in people with obesity and type 2 diabetes,4 Dr. Boyko says. In fact, Dr. Boyko writes in the review,1 ''the majority of published research provides evidence favoring the existence of an obesity paradox in type 2 diabetes mellitus."

He follows that with a substantial caveat saying, however: "The authors of a number of other studies, though, conclude that their results do not support this finding or can be explained by other factors." 

The moral: don’t be too hasty to accept reported good news; we have to look carefully at the research findings to really understand what is going on. As such, it is wise to approach the issue of obesity with more caution than relief, says Dr. Boyko.

Any supposed paradox, or inconsistency, due to obesity is most likely explained when researchers look more closely at the health status of individuals who also have high blood pressure, some forms of cancers, and other issues, Dr. Boyko tells EndocrineWeb.

After this intensive investigation,1 Dr. Boyko concludes that the obesity paradox is ''probably an artifact of several phenomena." By this, he means that there are other factors known to play a role in disease risk among those with obesity and diabetes.1,2 In particular, the disease effects related to body weight are more directly associated with an excess build-up of visceral (abdominal) fat.2,3

Is Skinny Fat a Thing? Refuting the Obesity Paradox

Among the issues that could be muddying up the role of obesity as a driver of poor health, Dr. Boyko says, is the imperfect measure known as body mass index, or BMI. The BMI was created as a screening tool to reflect body size based on a calculation of individual weight and height.

It is a measure of excess weight according to a person's height but doesn't directly measure fat mass, and doesn’t account for individual factors such as age, medical status, bone structure and muscle mass, or genetics.

The BMI does not reflect where body fat settles (ie, location), and we know that body fat distribution has a much greater influence on the risk of heart disease, says Dr. Boyko, citing previous research.5

What is most important for anyone wondering about his or her health risks, he says, is how much visceral fat one has—referring to the apple shape or fat that settles around the organs in the abdomen, particularly the pancreas, liver, and intestines. Some people who fall in the healthy weight range based on their BMI may actually have high amounts of visceral fat.2

Other reasons behind the obesity paradox include flawed research study designs or population differences that may skew the results,1 Dr. Boyko says.

Is Being Skinny Fat a Real Thing?  

"I don't think the obesity paradox represents a true association between obesity and reduced longevity or reflects your true risk for disease events and earlier death, particularly if you already have [type 2] diabetes or heart disease," says Dr. Boyko.

What would he tell someone who has obesity and type 2 diabetes? As you might expect, “I would tell them to do whatever work to lose even a little weight."

In support of his position refuting the obesity paradox, specifically in those with type 2 diabetes, he says, we need only consider the findings from the LookAhead trial.6

These researchers followed more than 5,400 men and women, all of whom had type 2 diabetes with overweight or obesity, to see if the group participating in an intensive weight loss program experienced a significant reduction in heart disease-related events and death.6

The individuals assigned to the lifestyle intervention group lost nearly 9% of their body weight by the end of the first year and managed to maintain at least 6% of lost weight at the end of the study (based on an approximate follow-up of nearly 10 years).

The study did not demonstrate a reduction in either outcome but neither did it show an increase, which would have been expected if obesity conferred a survival benefit like the obesity paradox contends,6 he says.

The well regarded, and often cited study stands as the best pushback against the concept of an obesity paradox in those with type 2 diabetes, says Dr. Boyko, and also supports seeking a safe, long-term approach to weight loss.

What about that person we all know who ignores advice, weighs too much, and yet seems healthy just the same? "There are always exceptions," he says.

While there are always a few very fortunate individuals among us who were dealt great genes, "we are talking about the average effect."  Most of us cannot count on having a Teflon genetic make-up that lets us live a long life regardless of our lifestyle choices.

Forget Body Weight—Central Adiposity Is Key

In another recent study,5 lead author Wei Bao, MD, PhD, assistant professor of epidemiology at the University of Iowa in Iowa City, and his colleagues found that normal weight women who had central obesity, measured as a large waist circumference, were at higher risk of dying from heart disease or cancer than women considered in the healthy weight range without the noted belly fat.  

To examine the impact of fat location versus overall weight, Dr. Bao's team looked at the medical records of more than 156,000 women in the long-running Women' Health Initiative (WHI) whose average age was 63 years.3

Compared with women who were considered at a healthy weight and without central abdominal fat, those also at normal weight but with increased abdominal adiposity had a 25% higher risk of dying from cardiovascular disease and a 20% increased risk of death associated with cancer,3 he says.

A ''normal" waist circumference was 34.65 inches (88 centimeters) or less, while an unhealthy measure of abdominal fat measured greater than 34.65 inches. In men, a waist circumference of 40 inches (or 102 centimeters) or more is considered linked to adverse health effects.

"The results of this trial reaffirm the importance of considering the waistline in assessing health risk," Dr. Bao tells EndocrineWeb. What is most important to appreciate, he says, is that the development of conditions like diabetes and heart disease arise even among the women who are at a so-called healthy weight.  

While our study looks only at women, he speculates that the same results can be expected for men, too, Dr. Bao says. He didn't look for a ''sweet spot" for waist size but advises people to focus on ''reducing the waistline as much as possible, or at least to reduce the pace at which the waistline increases."

BMI Not a Reliable Measure of Health and Disease

Dr. Bao agrees that the BMI is an imperfect measure, particularly because it cannot reflect where the body fat is located.

In reviewing the waist circumference study,3 Dr. Boyko points out that this measure, like BMI, can give you an indication of adiposity, but it too is far from perfect. "I've seen people with the same waist circumference," he says "but on further testing, such as with computer tomography or magnetic resonance imaging, I have found some patients with more hidden or internal visceral fat, while others present with mostly subcutaneous fat, which collects right under the skin instead of surrounding the organs."

Given the limits in body weight measures, Dr. Bao suggests that those who fall in the healthy weight range also know what your waist circumference is, so you have more information about your possible disease risks.

Dr. Boyko indicates that the number of women in the WHI study at normal weight and central obesity was relatively small, only 1,390,6 suggesting that it is fairly rare to be at a healthy weight but have an enlarged waist circumference.

Still, he would still advise anyone even in the healthy weight range to exercise daily and eat a mostly plant-based diet, such as the Mediterranean approach to eating to avoid any risk of diabetes, heart disease, and many forms of cancer.

Lastly, the newest data indicates that simply by cutting out 300 calories a day for at least two years, you are most likely to achieve healthier aging and greater longevity.7 While you don’t need to fast to live longer, just cutting out the soda or skipping dessert offers promise of a better quality of life.

Neither Dr. Boyko nor Dr. Bao have any relevant disclosures.

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