Wednesday, July 23, 2014

In Memorium: Albert (Mickey) J Stunkard

Stunkard twinsAs I spend my days at the 9th Canadian Obesity Network’s Summer Bootcamp for young trainees from Canada and around the world, I was saddened to learn of the passing of Mickey Stunkard, clearly one of the biggest names in obesity research – at a healthy age of 92.

With well over 500 publications to his name, Mickey is perhaps best known for his twin studies showing that the body weight of adopted identical twins reared apart resembles each other and that of their biological parents rather than the weight of their adoptive parents.

This work helped establish the basis for much of the genetic work on obesity that followed, clearly showing that differences in body weight between two individuals are much more accounted for by their difference in genetics than by differences in their “lifestyles”.

These findings were often misused in “nature vs. nurture” debates, an issue that serious scientists have long laid to rest in light of our current understanding that the two cannot be discussed separately, simply because genes and lifestyle interact on virtually every level – from molecules, to cells, to behaviours.

Here is what one obituary had to say about Mickey:

“He surveyed obesity treatment studies in the late ’50s and found that the nation’s diet programs could claim only a 2 percent success rate. He was an early advocate for the use of bariatric surgery to induce weight loss. He also published the first modern account of binge eating in obese individuals.”

I have had to pleasure to often hear him speak at conferences.

He will be dearly remembered.

@DrSharma
Kananaskis, AB

 

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Thursday, July 17, 2014

Infant Antibiotic Exposure and Obesity Risk

sharma-obesity-gut-buts1With all the interest in the role of the gut bacteriome in the development of obesity, it was only a matter of time before someone examined the relationship between antibiotic use and obesity risk.

This is exactly what Anita Kozyrskyj and colleagues from the University of Alberta, Edmonton, Canada, explored in a paper now published in the International Journal of Obesity.

For their study they linked rovincial healthcare records to clinical and survey data from a Canadian longitudinal birth cohort study, whereby antibiotic exposure during the first year of life was documented from prescription records.

Overweight and central adiposity were determined from anthropometric measurements at ages 9 (n=616) and 12 (n=431) years.

According to this analysis, infants receiving antibiotics in the first year of life were about twice as likely to be overweight later in childhood compared to those who were unexposed.

However, after adjustment for birth weight, breastfeeding, maternal overweight and other potential confounders, this association persisted in boys but not in girls. The reason for this discrepancy is not clear.

Although these findings are in line with the notion that early use of antibiotics may predispose to obesity, it is important to not that these type of studies cannot prove causality.

It may well be that other non-measured factors could explain this association (e.g. overprotective or lower SES parents may be more likely to use antibiotics in their infants – both factors are independently associated with higher rates of obesity).

Nevertheless, given the rather high rates of antibiotic exposure in infants it appears that this may well be a promising area for further research not just in the context of obesity but also for many of the other conditions that are now believed to be influenced by intestinal flora.

@DrSharma
Edmonton, AB

ResearchBlogging.orgAzad MB, Bridgman SL, Becker AB, & Kozyrskyj AL (2014). Infant antibiotic exposure and the development of childhood overweight and central adiposity. International journal of obesity (2005) PMID: 25012772

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Thursday, July 10, 2014

Can Germs In Your Drinking Water Help Prevent Obesity?

sharma-obesity-tap-water1In my show I joke about how I intend to import water from the river Ganges as a new obesity treatment that I will appropriately name “RunFast”.

Jokes aside, a study by Zhongyi Chen and colleagues, published in the Journal of Clinical Investigation, shows that treating mice with genetically modified bugs delivered through their drinking water can protect them from becoming obese even when fed a high-fat diet.

To be exact, the researchers used a strain of e coli bacteria genetically engineered to produce N-acylphosphatidylethanolamines (NAPEs), which are precursors to the N-acylethanolamide (NAE) family of lipids, normally synthesized in the small intestine in response to feeding and known to reduce food intake.

As their study shows, administration of these modified bacteria in drinking water for 8 weeks dramatically lowered food intake, weight gain, body fat, insulin resistance and liver fat in mice on a high-fat diet.

These “protective effects” lasted for at least 4 weeks after removal of these bacteria from the drinking water.

In another set of experiments the researchers also showed that this strain of bacteria reduced weight gain in a genetic model of mouse obesity.

Contrary to what one may believe, this study neither supports nor refutes the idea that gut bacteria may be partly responsible for the obesity epidemic.

Rather, the study primarily shows that bacteria may be used as a delivery system for “therapeutic doses” of molecules to the intestines – in this case, resulting in the modification of appetite and metabolism.

I would not be surprised if the therapeutic use of bacteria (genetically modified or not) opens up a whole new dimension of therapeutics – not just for obesity.

@DrSharma
Edmonton, AB

ResearchBlogging.orgChen Z, Guo L, Zhang Y, L Walzem R, Pendergast JS, Printz RL, Morris LC, Matafonova E, Stien X, Kang L, Coulon D, McGuinness OP, Niswender KD, & Davies SS (2014). Incorporation of therapeutically modified bacteria into gut microbiota inhibits obesity. The Journal of clinical investigation PMID: 24960158

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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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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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