Friday, August 8, 2014

Healthy Obesity: More Questions Than Answers?

sharma-obesity-visceral-fat-mriRegular readers will be well aware of the evidence that a subset of people living with obesity can be remarkably healthy despite carrying a rather large amount of body fat.

This issue of “healthy obesity” was the topic of the 13th Stock Conference of the International Association of the Study of Obesity, the proceeding of which are now published in Obesity Reviews.

As the authors note,

“The ‘healthy obese’ phenotype was described in the 1980s, but major advancements in its characterization were only made in the past five years. During this time, several new mechanisms that may be involved in health preservation in obesity were proposed through the use of transgenic animal models, use of sophisticated imaging techniques and in vivo measurements of insulin sensitivity. However, the main obstacle in advancing our understanding of the metabolically healthy obese phenotype and its related long-term health risks is the lack of a standardized definition.”

The latter is a real problem because finding people with obesity, who are truly metabolically and otherwise healthy becomes harder the higher the BMI gets – this makes the study of this phenomenon rather challenging.

Nevertheless,

“One of the most consistent characteristics of metabolic health in obesity across studies in humans is reduced liver lipid. This is likely the consequence of increased capacity for storing fat coupled with improved mitochondrial function in adipose tissue and decreased de novo lipogenesis in liver. This can also result in decreased deposition of lipids, including bioactive species, in skeletal muscle. Decreased adipose tissue inflammation with decreased macrophages and a unique T-cell signature with an anti-inflammatory circulating milieu were also suggested to characterize metabolic health in obesity. Anecdotal data support a possible role for healthier lifestyle, including increased level of physical activity and healthier diet. It remains to be established whether a favourable metagenomic signature is a characteristic of metabolic health in obesity.”

Finland’s, Dr Kirsi Pietiläinen explained that,

“..three energy dissipation pathways, oxidative phosphorylation, fat oxidation and amino acid catabolism showed preserved pathway activities in subjects who are MHO at a level similar to their lean counterparts. In contrast, these pathways were significantly down-regulated in adipose samples from obese twins with metabolic disturbances. Another potential hallmark of metabolic health, a favourable inflammatory profile of the adipose tissue was also observed in the MHO twins. Also, the fat cells of the MHO twins were smaller with evidence of more active differentiation processes within the fat tissue. As multiple mitochondrial pathways are vital in adipocyte differentiation [29], it is possible that mitochondrial malfunction impairs the development of new fat cells, which in turn results in an inability of the adipose tissue to expand under conditions of energy excess. This failure of fat cell proliferation has long been suspected to constitute the framework for ectopic fat storage, insulin resistance and type 2 diabetes.”

Other speakers discussed other aspects including immune function and microbiata in this phenomenon.

Finally, the authors concluded that,

“identifying underlying factors and mechanisms associated with this phenotype will eventually be invaluable in helping the scientific and medical community understand factors that predispose, delay or protect obese individuals from metabolic disturbances. It is essential to underscore that the MHO concept presently only address the cardio-metabolic risks associated with obesity; it is therefore important that patients who are MHO are still very likely to present many other obesity-related complications such as altered physical and/or physiological functional status, sleep problems, articulation and postural problems, stigma, etc. Importantly, the MHO concept supports the fact that classification based on excess adiposity per se (e.g. BMI or body composition if available) should be supplemented with obesity-related comorbidities, e.g. with fasting insulin as proposed by the Edmonton obesity classification system.”

Certainly a space to watch as we learn more and more about the “healthy obesity” phenotype.

@DrSharma
Edmonton, AB

ResearchBlogging.orgSamocha-Bonet D, Dixit VD, Kahn CR, Leibel RL, Lin X, Nieuwdorp M, Pietiläinen KH, Rabasa-Lhoret R, Roden M, Scherer PE, Klein S, & Ravussin E (2014). Metabolically healthy and unhealthy obese – the 2013 Stock Conference report. Obesity reviews : an official journal of the International Association for the Study of Obesity PMID: 25059108

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Thursday, June 26, 2014

Guidelines for Managing Overweight and Obesity in Adults

the obesity societyRegular readers may recall a previous post on guidelines on obesity management released by The Obesity Society (TOS) together with other organisations, including the American Heart Association and the American College of Cardiology, at Obesity Week in Atlanta last year (2013).

The bottom line, as I have blogged before, was the revelation of just how little we actually know about obesity.

For what it is worth, the complete guidelines are now published as a supplement to its July issue of the Obesity journal (Guidelines (2013) for Managing Overweight and Obesity in Adults: Full Report).

According to The Obesity Society’s press release,

TOS is investing in the improved treatment of obesity by making the full guidelines available in print so they can serve as a go-to resource for health practitioners around the world. Whether you are a physician, nurse, nutritionist or fitness trainer, every professional interacting with individuals with obesity can find value in this insightful treatment guide.

No doubt, a tremendous amount of work went into developing these guidelines – whether they will substantially change practice remains to be seen.

@DrSharma
Vancouver, BC

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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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Monday, June 23, 2014

Does More Energy In And Out Make It Easier To Maintain Energy Balance?

sharma-obesity-caloric_balance_scaleFrom every thing we know about obesity, the simplistic model of energy-in-energy-out (or Eat-Less-Move-More) approach to managing weight has not led us to any meaningful advances in obesity management. The number of people who can successfully manage their weight by this approach in the long-term is so minuscule, that every “success story” is considered “newsworthy”.

Now, a provocative paper by Gregory Hand and Steven Blair, published in US Endocrinology, suggests that what matters for good health is the amount of energy flowing through the system rather than the state of energy balance.

Thus,

“Recent findings suggest that a high energy flux, maintained by increasing energy expenditure, can improve an individual’s metabolic profile without changing weight.”

This, essentially, is a fancy way of saying, that simply moving more calories through your body by burning more calories (even if you instantly eat them back) benefits the organism irrespective of any impact this may have on body weight – or that exercise is good for you even if you do not lose weight.
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Anyone familiar with Steven Blair’s work (fat and fit is better than skinny and unfit) – will recognize the theme – but couching it in a concept of energy flux is a novel and interesting spin to this idea.

Apart from providing a theoretical model for how exercise may benefit you even if you don’t lose any weight doing it, the model may also have implications for weight management.

Thus,

“The significance of the model of energy regulation is twofold: First, the model suggests that energy balance, and maintaining a stable weight is more easily achieved at a high energy flux. Second, a high energy flux can be achieved by matching a high energy intake with equivalent high energy expenditure, or by increasing energy stores (gaining weight). Of note is that these two characteristics of the model suggest that the biological system was designed to maintain a high energy flux, and increasing energy stores is a quite viable mechanism to achieve this level of energetics. An extensive body of research indicates that multiple and redundant mechanisms regulate the ‘drive’ for energy intake. The high energy flux is attained by matching the intake with expenditure and/or a change in energy storage. Weight gain is consistent with high energy flux combined with low energy expenditure, and it follows that attempting to achieve energy balance at a low energy flux (sedentary behavior combined with food restriction) is not a long-term strategy for weight maintenance.”

The biological question that pops into my mind of course is as to how exactly the body would sense this “flux”. While it is easy to see how the body would sense energy stores (e.g. through hormonal signals such as leptin), it is not clear how the body would monitor flux (after all, to regulate something, it needs to be measured).

This is not something that the authors delve into, thus leaving a somewhat unsatisfying gap in what otherwise makes for an interesting hypothesis.

@DrSharma
Toronto, 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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