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Obese, but Metabolically Healthy Individuals: at Lower Risk for Death?

Friday, December 11, 2009 Posted by Peter Janiszewski, PhD

Very recently, an interesting study was published looking at the risk of early mortality among metabolically-healthy obese individuals – a topic we’ve covered on a number of occasions on Obesity Panacea. The authors of this landmark study published in the journal Diabetes Care are actually close friends of ours (Dr. Jennifer Kuk and Dr. Christopher Ardern), and both are alumni of Queen’s university. Now that the media frenzy surrounding their recent study has subsided, Dr. Kuk was kind enough to answer a few questions about the study and enlighten our readers.

Dr. Kuk is currently an Assistant Professor at the School of Kinesiology and Health Science at York University. Before Dr. Kuk was at York University, she did her PhD in the same lab that I am currently in (Queen’s university). Dr. Kuk has been instrumental in shaping my research interests while at Queen’s and beyond, and over the years has provided tremendous guidance in many areas. I could not be happier to showcase some of her pioneering research on Obesity Panacea.

Without further adieu, enjoy the interview.

OP: If you were to sum up the main findings of your study to a non-scientist at a dinner party, what would you say?

Dr. Kuk: I don't get invited to dinner parties, but if I were, I'd say that "My study shows that individuals who are obese and do not have common diabetes and heart disease risk factors die at the same rate as those 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".

OP: Why do you think the prevalence of metabolically-healthy obesity in your study was so much lower than previously reported in others (6% vs 20-30%)?

Dr. Kuk: The prevalence was lower in our study as compared to others simply because we used a more strict definition of metabolically normal. Other studies used insulin resistance or the metabolic syndrome (3+ risk factors) alone, but we defined 'metabolically healthy' as the absence of insulin resistance or any metabolic syndrome criteria. We felt this would be a more accurate definition of 'metabolically healthy' as each of the metabolic syndrome criteria are associated with morbidity and mortality alone.

OP: How do you reconcile the findings from the current study with those of prior studies suggesting that metabolically-health obese individuals are at no greater risk for developing type-2 diabetes or cardiovascular disease than normal weight individuals?

Dr. Kuk: Although I don't know which studies you are referring to exactly, but in our study, 80% of the deaths in the metabolically-healthy obese were due to cancer and 'other' causes. Other causes are likely traumatic injuries, which highlights an important point. Obese individuals are less likely to survive a trauma as compared to normal weight individuals despite similar injuries. This is related to longer transport times due to their higher body weight, and difficulty assessing and treating the injuries due to their increased size. 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, this study fits in line with the idea that these indiviudals are not more likely to develop these metabolic diseases, but still die from other causes.

OP: Recently, Drs. Sharma and Kushner proposed a new staging system for obesity treatment suggesting that obese individuals without established metabolic risk should be counseled to maintain current weight, rather than lose weight (Read about this on Dr. Sharma's Obesity Notes blog). Do the results of your study agree or disagree with these recommendations?

Dr. Kuk: One can examine this question from a theoretical or practical standpoint. From a theoretical stand, weight loss improves metabolic factors, functionality and serveral psychological and social factors, and thus it would be intutitive to recommend that all obese lose weight. However, from a practical perspective it may be unethical to recommend an individual who is not presenting with overt disease to try to lose weight as most indiviudals fail to maintain their weight loss over the long term. Repeatedly failed attempts to maintain weight loss has been shown to elevate one's risk for diabetes, CVD and cancer for a given BMI. In other words, it may be better to recommend maintenance of weight rather than prescribing weight loss, knowing that they are likely to fail and be worse off because of it. Though we did not examine this issue, Sharma and Kushner's staging system examines non-metabolic consequences as well, and it is reasonable to assume that these are equally important to examine as they are also important aspects of health, and inclusions of these factors may alter the associations observed.

OP: Are metabolically-healthy obese individuals actually healthy?

Dr. Kuk: I think that whether metabolically-healthy obese are actually healthy is dependent upon the accuracy of the definition. As we see that obese without CVD or diabetes risk factors are at elevated cancer risk implies that our definition of metabolically healthy is not capturing cancer metabolic risk factors. Similarly, risk for trauma events may also reflect aspects of health that may or may not be captured by metabolic risk factors, but are crucial aspects of health. For example, musculoskeletal fitness would be a predictor of risk of falling or functionality.

Thus, if we used a more encompassing definition, we would likely see that these metabolically-healthy obese may be at lower risk for mortality and are healthy. However, as our definition only identified 6% metabolically healthy obese, I would suspect that an all encompassing definition for healthy obese would be a very minuscule proportion of the population.

OP: What was the most interesting point raised by a reviewer during the publication process of this study?

Dr. Kuk: The most interesting point was surrounding whether metabolically normal obese should lose weight. I don't think there is a clear answer, but this study definitely provides food for thought.

OP: What came as the biggest surprise to you in doing this study?

Dr. Kuk: Our main finding was the biggest surprise. We actually expected that the metabolically normal obese were at lower risk for mortality.

Thanks very much to Dr. Jennifer Kuk!

Have a great weekend!


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Kuk, J., & Ardern, C. (2009). Are Metabolically Normal but Obese Individuals at Lower Risk for All-Cause Mortality? Diabetes Care, 32 (12), 2297-2299 DOI: 10.2337/dc09-0574

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8 Response to "Obese, but Metabolically Healthy Individuals: at Lower Risk for Death?"

  1. Darya Said,

    Wow, really interesting. Thanks for sharing!!

    A lot to think about. It sounds like a healthy lifestyle is the most important factor, but there's so much going on here.

    Posted on December 11, 2009 at 12:42 PM

  2. Beth Said,

    Wow!! Thanks so much for getting the additional details.

    Did you see the release today about BMI and breast cancer?

    They noted the same point about "more advanced disease at diagnosis."

    Hard not to think that this is as much about stigma and avoiding the doctor as it is biochemistry.

    Posted on December 11, 2009 at 1:06 PM

  3. Peter Janiszewski, PhD (Cand.), MSc Said,

    @ Darya - you are very welcome:)Thanks for the comment.

    @ Beth - Yes, thanks - I actually saw it on the news last night.

    You make an excellent point regarding the findings of this study being possibly explained by more social rather than physiological factors. I would love to see a study try and assess whether such a hypothesis pans out to be true - it is certainly very plausible.

    Posted on December 11, 2009 at 1:26 PM

  4. Beth Said,

    Peter, I wouldn't say that that these findings are more explained by social factors. As Taubes says, it is the things that make you fat that make you sick. And those are pretty physiological in nature.

    That said, when you are talking mortality as a result, access to health care sure looks to be a huge factor whether it is lack of access for economic reasons or whether it is psychological (e.g., stigma).

    Posted on December 11, 2009 at 1:31 PM

  5. Jennifer Said,

    Thanks for you interest in the article. In that paper we did adjust for income, physical activity and dietary fat intake, and income was a significant predictor of lower mortality rates, while physical activity and dietary fat intake was not. This is not to say that these factors are not important, but likely their effects are observed in part through differences in the metabolic profile of the groups. The point about stigma is very interesting and highlights the importants of educating our society not to stigmatize based on weight, and I guess it starts with us.

    Posted on December 11, 2009 at 6:26 PM

  6. Thomas Said,

    Interesting indeed, however:

    "Are metabolically-healthy obese individuals actually healthy?"

    How would you prove/disprove this question/statement other than observing metabolically-healthy obese people?

    Posted on December 11, 2009 at 6:59 PM

  7. Peter Janiszewski, PhD (Cand.), MSc Said,

    @ Jennifer - Thanks for participating in the discussion Dr. Kuk. This would mark the first time an author of a study discusses their findings with our readers (aside from when Travis and I discuss the results of our own studies). We're glad to have you here:)

    @ Thomas - That question is a bit of a trick as it really depends on your definition of health. While they may have a normal metabolic profile, obese individuals could still suffer from osteoarthritis, sexual dysfunction, depression, sleep apnea, and a plethora of other ailments that would deem someone "unhealthy". As an aside, Dr. Kuk actually asked me that very question when I was presenting a study of mine on metabolically healthy obese individuals at a recent conference. Thus, I figured I could use this opportunity to try and stump Dr. Kuk:)

    Posted on December 11, 2009 at 11:42 PM

  8. Thomas Said,

    Peter, i was going with your choice of topic "lower risk for death", therefor health should include anything that avoids death ;)
    Would also include injury recovery and chances of getting injured in the first place. but that's just me :)

    Posted on December 12, 2009 at 9:05 AM


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We are PhD students in the School of Kinesiology and Health Studies at Queen's University in Kingston, Ontario. Our research focuses on the relationships between obesity, physical activity, and health risk. This blog is our attempt to consider the many "cures" for obesity that we read about on a daily basis. Enjoy.


The opinions expressed here belong only to Peter and Travis and do not reflect the views of any organization. Any medical discussion on this page is intended to be of a general nature only. This page is not designed to give specific medical advice. If you have a medical problem you should consult your own physician for advice specific to your own situation.

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