Tuesday, July 8, 2014

Does BMI Underestimate Adiposity in Kids?

sharma-obesity-kids-scale2Regular readers are well aware of my reservations regarding the use of BMI as a diagnostic parameter in clinical practice. After all, while BMI may tell us how big someone is, it certainly is not a good measure of how sick someone is.

But to be honest, BMI was never intended as a measure of disease – it was (at best) introduced as a surrogate measure of adiposity (fatness).

Nevertheless, supporters of BMI continue to argue that it is still a good measure of fatness and as such should remain part of standard assessment – even in kids.

Now, a paper by Javed and colleagues, published in Pediatric Obesity, examines how well BMI performs as a means to identify obesity as defined by body fatness in children and adolescents.

The authors conducted a systematic review and meta-analysis of 37 studies in over 53,000 participants assessing the diagnostic performance of BMI to detect adiposity in children up to 18 years.

While the commonly used BMI cut-offs for obesity showed showed a high specificity (0.93) to detect high adiposity, the sensitivity was much lower (0.73) – particularly in boys.

This means that kids who exceed the current BMI cut-offs are indeed very likely to have fatter bodies (for what it’s worth).

On the other hand, relying on BMI cut-offs alone will miss as many as 25% of kids whose body fat percentage exceeds current definitions of adiposity.

Thus, assuming that bod fatness or adiposity is indeed a clinically useful measure of health, the use of BMI alone will ‘underdiagnose’ adiposity in a significant proportion of kids (especially boys) who may well be at risk from excess fat.

A word of caution about fatness is certainly in order – as in adults, much depends on exactly where the fat is located (abdominal or ectopic vs. subcutaneous) and other factors (e.g. cell size, inflammation, insulin sensitivity, etc.).

Thus, even if BMI was a perfect measure of body fat, it would probably still require further examinations and tests to determine exactly whether or not this “extra” fat poses a health risk.

As in adults, a clinical staging system similar to the Edmonton Obesity Staging System may be a fat better indicator of determining which kids may need to worry about their body fat and which don’t.

@DrSharma
Edmonton, AB

Hat tip to Kristi Adamo for pointing me to this study

ResearchBlogging.orgJaved A, Jumean M, Murad MH, Okorodudu D, Kumar S, Somers VK, Sochor O, & Lopez-Jimenez F (2014). Diagnostic performance of body mass index to identify obesity as defined by body adiposity in children and adolescents: a systematic review and meta-analysis. Pediatric obesity PMID: 24961794

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Wednesday, June 25, 2014

Social Anxiety As A Deterrent To Physical Activity

sharma-obesity-distored-body-image1Social anxiety, defined as persistent fears of one or more social situations in which the person is exposed to others and expects to be scrutinized, has been reported in as many as one in ten individuals with overweight or obesity.

Now, a paper by Abbas Abdollahi and Mansor Abu Talib, published in Psychology, Health and Medicine, examines the relationship between social anxiety and sedentary behaviour in this population.

The researchers surveyed 207 overweight and obese students (measured heights and weights) using a number of validated instruments to assess social anxiety, sedentariness and body esteem.

As one might expect, social anxiety was associated with lower body esteem and higher sedentary behaviour.

The key mediator in this relationship was body dissatisfaction and poor body esteem.

Thus,

“…obese individuals with poor body esteem are more likely to report social anxiety, because they are concerned about negative evaluation by others; therefore, obese individuals indicate avoidance behaviour, which, ultimately, leads to social anxiety.”

The implications of these findings are obvious,

“First, when assessing the social anxiety in individuals, it is important to account for the presence of sedentary behaviour in addition to other psychological risk factors. Second, reducing sedentary behaviour can alter the effect of social anxiety factors; this may be a significant factor to incorporate into social anxiety treatment programmes. Reducing social anxiety in individuals is a main part of any clinical intervention. Third, the findings of the current study suggest that health professionals should encourage obese individuals with social anxiety to reassure their value and abilities regardless of their weight or body shape, and assist them to recognize that everybody is unique and that differences between individuals are valuable.”

This will take more than simply telling people with overweight to be more active. It will certainly require targeted and professional help to overcome body dissatisfaction and low self esteem.

Or, even better, we need to do all we can to help people gain more confidence and be accepting about their own bodies in the first place.

@DrSharma
Vancouver, BC

ResearchBlogging.orgAbdollahi A, & Talib MA (2014). Sedentary behaviour and social anxiety in obese individuals: the mediating role of body esteem. Psychology, health & medicine, 1-5 PMID: 24922119

 

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Friday, June 20, 2014

Your Body Thinks Obesity Is A Disease

sharma-obesity-adipose-tissue-macrophageYesterday, the 4th National Obesity Student Summit (#COSM2014) featured a debate on the issue of whether or not obesity should be considered a disease.

Personally, I am not a friend of such “debates”, as the proponents are forced to take rather one-sided positions that may not reflect their own more balanced and nuanced opinions.

Nevertheless, the four participants in this “structured” debate, Drs. Sharon Kirkpatrick and Samantha Meyer on the “con” team and Drs. John Mielke and Russell Tupling on the “pro” team (all from the University of Waterloo) valiantly defended their assigned positions.

While the arguments on the “con” side suggested that “medicalising” obesity would detract attention from a greater focus prevention while cementing the status quo and feeding into the arms of the medical-industrial complex, the “pro” side argued for better access to treatments (which should not hinder efforts at prevention).

But a most interesting view on this was presented by Tupling, who suggested that we only have to look as far as the body’s own response to excess body fat (specifically visceral fat) to determine whether or not obesity is a disease.

As he pointed out, the body’s own immunological pro-inflammatory response to excess body fat, a generic biological response that the body uses to deal with other “diseases” (whether acute or chronic) should establish that the body clearly views this condition as a disease.

Of course, as readers are well aware, this may not always be the case – in fact, the state of “healthy obesity” is characterized by this lack of immunological response both locally within the fat tissue as well as systemically.

Obviously, it will be of interest to figure out why some bodies respond to obesity as a disease and others don’t – but from this perspective, the vast majority of people with excess weight are in a “diseased” state – at least if you asked their bodies.

While this is a very biological argument for the case – it is indeed a very insightful one: it is not the existence of excess body fat that defines the “disease” rather, how the body responds to this “excess” is what makes you sick.

As readers, are well aware, there are several other arguments (including ethical and utilitarian considerations) that favour the growing consensus on viewing obesity as a disease.

Of course,  calling obesity a disease should not detract us from prevention efforts, but, as I often point out, just because be treat diabetes or cancer as diseases, does not mean that we do not make efforts to prevent them.

If calling obesity a disease increases resources towards better dealing with this problem and helps take away some of the shame and blame – so be it.

@DrSharma
Waterloo, Ontario

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Thursday, June 19, 2014

Fat Activism in Canada

Dr. Jenny Ellison, Trent University, Peterborough, Ontario, Canada

Dr. Jenny Ellison, Trent University, Peterborough, Ontario, Canada

Yesterday’s opening plenary talk at the 4th Canadian Obesity Student Meeting, hosted by the Canadian Obesity Network’s Students and New Professionals (CON-SNP) network, was given by Dr. Jenny Ellison from the  Frost Centre for Canadian & Indigenous Studies at Trent University, on the history of fat activism in Canada.

In her talk, Ellison, presented a broad historical overview of how fat stigma and messaging around fat has evolved over the years.

From the early “Christian” view of obesity as a deadly sin, moral failing and lack of will power and the beginning of the obsession with body shape and size in the early half of the 20th century to the growing movement of fat acceptance and understanding of the negative consequences of fat stigma and fat politics for larger people.

She concluded with an overview of how informal networks within the fat activist movement are self-organising online sharing a wide range of information from finding physicians to identifying safe spaces where they can interact.

Ellison also complimented the Canadian Obesity Network on taking a strong stance against weight stigma and discrimination, thus opening up the possibility for a different future.

A recent paper by Ellison on this subject is available here.

@DrSharma
Waterloo, ON

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Wednesday, June 18, 2014

4th Canadian Obesity student Meeting (COSM 2014)

Uwaterloo_sealOver the next three days, I will be in Waterloo, Ontario, attending the 4th biennial Canadian Obesity Student Meeting (COSM 2014), a rather unique capacity building event organised by the Canadian Obesity Network’s Students and New Professionals (CON-SNP).

CON-SNP consist of an extensive network within CON, comprising of over 1000 trainees organised in about 30 chapters at universities and colleges across Canada.

Students and trainees in this network come from a wide range of backgrounds and span faculties and research interests as diverse as molecular genetics and public health, kinesiology and bariatric surgery, education and marketing, or energy metabolism and ingestive behaviour.

Over the past eight years, since the 1st COSM was hosted by laval university in Quebec, these meetings have been attended by over 600 students, most presenting their original research work, often for the first time to an audience of peers.

Indeed, it is the peer-led nature of this meeting that makes it so unique. COSM is entirely organised by CON-SNP – the students select the site, book the venues, review the abstracts, design the program, chair the sessions, and lead the discussions.

Although a few senior faculty are invited, they are largely observers, at best participating in discussions and giving the odd plenary lecture. But 85% of the program is delivered by the trainees themselves.

Apart from the sheer pleasure of sharing in the excitement of the participants, it has been particularly rewarding to follow the careers of many of the trainees who attended the first COSMs – many now themselves hold faculty positions and have trainees of their own.

As my readers are well aware, I regularly attend professional meetings around the world – none match the excitement and intensity of COSM.

I look forward to another succesful meeting as we continue to build the next generation of Canadian obesity researchers, health professionals and policy makers.

You can follow live tweets from this meeting at #COSM2014

@DrSharma
Waterloo, Ontario

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In The News

Diabetics in most need of bariatric surgery, university study finds

Oct. 18, 2013 – Ottawa Citizen: "Encouraging more men to consider bariatric surgery is also important, since it's the best treatment and can stop diabetic patients from needing insulin, said Dr. Arya Sharma, chair in obesity research and management at the University of Alberta." Read article

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