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Can you be both obese and healthy?

The views expressed are those of the author and are not necessarily those of Scientific American.


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Countless epidemiological studies have shown that as you move from a normal body weight towards obesity the risk of many chronic diseases increases exponentially. However, more and more research suggests that the relationship between body weight and health is much more nuanced than previously thought.

Recent estimates suggest that approximately one in three obese individuals remain metabolically healthy (displaying normal blood glucose, blood lipids, blood pressure, and a healthy cytokine profile) despite their excess weight. These same individuals may have a similar risk of developing heart disease and diabetes as their skinny counterparts and they may actually become less healthy by losing weight!

Thus, as we shall see below, there is certainly more to health than the number on one’s bathroom scale.

Historical background:

It all started in 1965. Two researchers, Albrink and Meigs, were performing a general investigation into the health of factory workers, and noted a rather counterintuitive result: that many obese men had healthy levels of triglycerides in their blood.

In 1982, Ethan Sims first included the designation of "healthy obese" subtype in his classification of obesity, thereby first identifying a unique subset of obese individuals that appear to be at least partially protected from the development of the metabolic disturbances generally attributed to obesity.

Unfortunately, despite awareness of the metabolically health obese phenotype for close to 30 years, there currently exist no established criteria by which to define these individuals.

What defines a metabolically healthy obese individual?

The defining characteristics of the metabolically healthy obese phenotype, in contrast to obese individuals with metabolic risk, include limited abdominal, particularly visceral fat accumulation, an earlier onset of obesity (<20 years) and high levels of physical activity. Additionally, black obese individuals have a greater tendency of being metabolically healthy in contrast to white obese.

Japanese sumo wrestlers are often used as a popular example of metabolically healthy obese. They are morbidly obese and yet due to their high level of activity have very little visceral fat accumulation, tons of muscle mass, and a healthy metabolic profile—until they stop training, that is. Once their activity drops off, so does their fitness, and they begin to accumulate excess fat in deleterious locations, matched by a worsening in their metabolic profile.

Risk of heart disease and diabetes among healthy obese individuals

Ok, so maybe there are some people with excess weight who somehow manage to maintain a reasonable healthy metabolism. But what about the chances of developing chronic diseases such as diabetes or cardiovascular disease—two common ailments tied to carrying excess weight?

Two large studies have sought to answer this question, and their results may surprise you.

In the first study, 2902 men and women were subdivided into different groups based on their weight and metabolic status and were prospectively followed for up to 11 years to see who would develop type-2 diabetes or cardiovascular disease.

And what say the results?

In terms of risk for developing cardiovascular disease or type 2 diabetes, metabolically healthy obese were at NO higher risk in comparison to their equally healthy, but normal weight individuals.

The authors of this study provide the following conclusion [emphasis added]:

"[...] in the absence of metabolic abnormalities, obesity itself did not increase risk for cardiovascular disease and was a relatively weak risk factor for incident diabetes."

A similar conclusion was reached by Canadian researchers following a group of 1824 men for a duration of 13 years:

"The results of this prospective population-based study indicate that the risk of ischemic heart disease associated with a high body mass index depended entirely on whether features of insulin resistance syndrome were simultaneously present."

Thus, it appears that 1 in 3 obese individuals is not only metabolically healthy, but their risk of disease is equal to that of their leaner counterparts.

A Caveat: Are metabolically healthy obese individuals REALLY healthy?

But, is there more to health than the level of triglycerides in one’s blood, or their risk of diabetes or cardiovascular disease? And if we consider other, potentially more telling outcomes—such as mortality—will metabolically healthy obese individuals still be considered healthy?

A 2009 study by Canadian researchers, asked this important question using prospective data on 6,011 men and women from the Third National Health and Nutrition Examination Survey.

Their results provided the first chink in the armour of the metabolically healthy obese concept.

In describing the major finding, Dr. Kuk, the primary author of the study, said this:

"Individuals who are obese and do not have common diabetes and heart disease risk factors die at the same rate as those obese individuals who do. This means being overweight alone puts you at higher risk for dying, even though you do not high blood pressure, high cholesterol or high blood sugar. This highlights the negative health impact of body weight alone".

Why the discrepancy?

Quite simply, there are numerous health issues brought on by carrying excess weight that are not always metabolic (i.e. joint problems due to excess load, skin infections, depression, etc.). Additionally, obese individuals are less likely to survive a trauma as compared to normal weight individuals despite similar injuries, due to longer transport times due to their higher body weight, and difficulty assessing and treating the injuries. Further, they are less likely to see their physicians regularly, which may be in part why cancer is generally diagnosed in obese individuals at later stages.

Thus, it is now believed that despite being metabolically healthy, obese individuals may still be far from optimal health.

Should healthy obese people lose weight?

In 2008, in response to a recent study, the answer to this question may have been no.

In this small study, researchers reported a VERY paradoxical finding: when otherwise healthy obese women lose weight via dieting their insulin sensitivity (a marker of diabetes risk) worsens. That is, they become less healthy in response to weight loss.

Even the authors of the study had no idea how to explain the findings.

Being intrigued with this finding, I conducted a similar study in a larger sample of metabolically healthy men and women as part of my PhD thesis.

In the recently published study, a total of 63 metabolically healthy obese men and women and 43 metabolically unhealthy obese men and women participated in three to six months of exercise and/or diet weight-loss intervention.

As you’d expect, body weight and body fat were significantly reduced in all subjects.

More importantly, insulin sensitivity improved after weight loss in both the metabolically healthy (by about 20 percent) and metabolically unhealthy obese individuals. However, the improvement was greater in the metabolically unhealthy subjects.

Thus, the recent results suggest that while the metabolic benefit of weight loss among healthy obese may be less drastic, there is certainly no reason to fear a deterioration of metabolic health.

Take home message:

Although a fair number of obese individuals may have a perfect metabolic profile, it appears they may still experience negative consequences of their excess weight. Furthermore, weight loss achieved via lifestyle intervention appears to still bring about some metabolic benefit among previously healthy obese individuals. Given the numerous nonmetabolic benefits of weight loss, all obese individuals certainly have something to gain from a modest reduction in body weight as achieved by a healthier lifestyle.

Image credit: Magnus D, from Flickr

About the author: Peter Janiszewski has a PhD in clinical exercise physiology. He is a published obesity researcher, medical writer, science blogger and an advocate of new media in scientific knowledge translation. He blogs at Obesity Panacea and Science of Blogging and regularly tweets as @PMJaniszewski.

 

The views expressed are those of the author and are not necessarily those of Scientific American.

 

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Comments 7 Comments

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  1. 1. Colo_kea 12:21 pm 01/18/2011

    Four things:
    1. Please define what you mean by obese. Do you mean borderline obese or morbidly obese? What’s the BMI range you’re talking about?
    2. My doctor considers me obese with a BMI of 29. However, at the age of 48, I can run 4.5 miles, lift 70 lbs repeatedly, bike 3.1 mi in 10 min., balance on the fit ball on my knees and lift weights, etc. I also come out healthier than most people on all the medical tests (except that I have mild arthritis). So that speaks to your "can obese people be healthy?" question. I do agree, however, that both because of my age and my weight, I have careful not to injure myself.
    3. For an obesity-unrelated illness, I have to take medicine that causes weight gain. What says obesity research about this?
    4. I do have hypoglycemia (not diabetes-related). Is this an obesity-related illness?
    Thanks for this post and for your regular blog, Obesity Panacea. Good to have seen you in the crowd and ScienceOnline2011.

    Link to this
  2. 2. Semiahmoo 12:22 pm 01/18/2011

    A "healthy obese" person who is actually less healthy after losing weight is like a "healthy smoker" who is less healthy after ceasing self abuse. In other words, utter nonsense.

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  3. 3. miriamgordon 10:22 pm 01/19/2011

    Congratulations for having the courage to challenge deeply entrenched public and medical opinion by introducing the concept of nuance into the puzzle of obesity. Despite your sharp insight, however, you still remain in the dark, along with most of the western world, by retaining the idea that weight loss is a practical solution. Weight loss is a catch-22: every effort, however well intentioned, is almost always followed by a rebound and actually results in even more weight gain. Thus, there are many pieces to the obesity puzzle that have yet to be sussed out. This "rebound" phenomenon has been documented in medical literature so many times, much more than the "healthy obesity" phenotype, and yet those who believe they have the answers still insist that the overweight and obese lose weight. Encouraging positive lifestyle changes are great and can improve quality of life for many, but there is no point anymore in focusing on the number on the scale, or BMI.

    Recently, I heard Kelly Brownell, Director of the Rudd Center for Food Policy and Obesity at Yale, speak about the current priorities of the Center. The author of one of the most famous manuals on weight loss programs, Brownell is now directing all his energies toward fighting the "obesogenic environment" in western countries by attacking the ability of "big food" companies to market unhealthy foods. Kelly Brownell also happens to be a very fat man. I definitely do not mean this as an insult – I consider myself fat and accept that as an objective description. However, it appears Brownell has come to terms with the fallacy of weight loss. If he can do it, so can we.

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  4. 4. Colo_kea 9:33 am 01/20/2011

    miriamgordon – good points! Esp. about the rebound effect. I have found that if I had just been happy with a certain weight and kept it rather than trying to lose more weight … well, I would be happy to just be at that certain weight!
    Another item I will bring up again: Some of us are overweight in part due to medications that cause weight gain beyond our control. I work out ~10hr/week and even with reduced calories struggle to maintain my body weight.
    Oh, and one more point my husband brought up – and I recognize that this wasn’t part of the point of this blog – people can be thin and unhealthy too. It’s called "skinny fat" – excess body fat compared to muscle mass. I’d like to see a discussion of that compared to obesity.

    Link to this
  5. 5. Palaverer 12:18 pm 01/20/2011

    Interesting article and comments. I’d also like to point out that some of the negative affects of obesity can be fixed by social means. Depression, lower quality care, and avoidance of medical care, are problems usually caused by how society treats fat people, not the fat itself.

    Link to this
  6. 6. caejn 10:24 pm 02/4/2011

    Just want to share an insight about this topic on weight loss:
    The world has become poorly obese, rapidly. With the emergence of super high technologies, there are lots of distractions from keeping us getting out and moving, especially our children. Statistics shows that there are:
    · 64% of people in the US are overweight
    · 48% of people in Europe are overweight
    · 27% of Americans are classified as obese
    · Obesity is responsible for 325,000 deaths per year
    · Obesity cost an estimated $75 billion in 2003 because of its long and expensive treatment,
    · 300 million people worldwide are obese,
    · 750 million people worldwide are overweight
    · Weight loss market forecast to hit $61 billion by 2008
    · 400,000 deaths each year may be attributed to obesity.
    This problem affects our world immensely. Our ancestors were not overweight that is why their span of life is longer than ours today. Yes, some of us in our generation also live longer now, but this is only because of our advances in medicine and technology. Most of health problems today such as cancer, heart problems, anxiety, stress, organ function and a lot more can be correlated to being overweight.
    That’s why; we parents should discipline our children with their eating habits and daily activities so we could save them from this kind of sicknesses. But, if your child is already overweight and obese, still we can do something about it to make their life easier, healthier, and happier. Please click link below. If you can’t click, just copy and paste or type the link below into your browser:

    http://abef0ao9tg2pbsen0indtz6obf.hop.clickbank.net/

    This diet program was created through a collaboration of dieting and nutritional experts. They are using a combination of technology with some of the most proven dieting techniques. It has been constructed and refined over the years to maximize weight loss. This diet program has helped over 10,000 people already lose weight. So if you love your child, please do something about his/her obesity condition. Start it TODAY!

    Link to this
  7. 7. imhsar 5:10 am 11/10/2011

    There are other ways to find out if a person is obese, but experts believe that a person’s body mass index (BMI) is a most accurate fat in children and adults. Adult BMI over 30 is considered overweight. You will be surprised to know that almost one third of the world population is overweight Read more on
    http://www.aasthahealthcare.com/Obesity-Global-Epidemic.htm

    Link to this

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