Thursday, April 24, 2014

Pectin is Not Pectin is Not Pectin is Not Pectin….

sharma-obesity-weight-loss-supplementsAdding fibre to your diet is one of the most commonly suggested strategies to increase satiety – however, we have long known that fibre is not fibre, as several subtypes of fibre vary widely in their different impacts on satiation.

Now, it turns out that even within distinct groups of fibre (in this case pectin), much depends on the actual physical form in which this fibre is ingested.

Thus, a randomised controlled trial by Anne Wanders and colleagues, published in Physiology and Behaviour, tested the satiety and metabolic effect of no pectin, bulking pectin (10 g), viscous pectin (10 g), or gelled pectin (10 g), whereby the latter was supplemented either as capsules (10 g) or as liquid (10 g).

Here is how the authors summarize their findings:

“Appetite was reduced after ingestion of gelled pectin compared to bulking (p < 0.0001), viscous (p = 0.005) and no pectin (p < 0.0001), without differences in subsequent energy intake (p = 0.32). Gastric emptying rate was delayed after gelled pectin (82 ± 18 min) compared to no pectin (70 ± 19 min, p = 0.015). Furthermore, gelled (p = 0.002) and viscous (p < 0.0001) pectin lowered insulin responses compared to no pectin, with minor reductions in glucose response. Regarding methods of supplementation, appetite was reduced after ingestion of the gelled test product compared to after capsules (p < 0.0001) and liquid (p < 0.0001). Energy intake was lower after ingestion of capsules compared to liquid (− 12.4%, p = 0.03).”

If you are now totally confused, so am I.

Clearly, pectin is not simply pectin – even for the same amount (10 g), much depends on exactly what form of pectin we are talking about – bulked, gelled, viscous, liquid, capsules?

They are all different!

And herein lies the problem with focussing on single nutrients – fibre is by no means alone in that the form and context in which it is consumed matters.

Along similar lines, fat is not fat, carbs are not carbs, protein is not protein, sugar is not sugar, fruit is not fruit, meat is not meat, veggies are not veggies, super foods are not super foods, and miracle supplements are not miracle supplements.

This is exactly why all dietary advice needs to be taken with a hefty pinch of salt.

@DrSharma
Edmonton, AB

ResearchBlogging.orgWanders AJ, Feskens EJ, Jonathan MC, Schols HA, de Graaf C, & Mars M (2014). Pectin is not pectin: A randomized trial on the effect of different physicochemical properties of dietary fiber on appetite and energy intake. Physiology & behavior, 128, 212-9 PMID: 24534170

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Wednesday, April 23, 2014

How Lifestyle Affects Your Gut Bugs

Dr. Jens Walter, Associate Professor and Campus Alberta Innovation Program (CAIP) Chair for Nutrition, Microbes and Gastrointestinal Health, University of Alberta

Dr. Jens Walter, Associate Professor and Campus Alberta Innovation Program (CAIP) Chair for Nutrition, Microbes and Gastrointestinal Health, University of Alberta

In my show, “Stop Being a Yo-Yo“, I joke about the notion that the bugs that live in your gut can be significant contributors to your weight problems.

All joking aside, the emerging recognition that your intestinal flora (a fancy term for gut bugs) can indeed affect your metabolism and other aspects of your health in rapidly evolving into one of the most promising avenues of nutrition and obesity research.

Reason enough for me to welcome Jens Walter, a new recruit to the University of Alberta as the Campus Alberta Innovation Program (CAIP) Chair for Nutrition, Microbes and Gastrointestinal Health.

Jens describes his research interest as follows:

“Dr. Walter’s research is primarily concerned with the microbial ecology of the human and animal gastrointestinal tract and the metabolic and immunological interactions between the microbiome and its host in relation to health. He views the interrelationship of gut microbes with their host as a symbiosis and is especially interested in the evolutionary processes that have shaped this partnership and the biological outcomes for both the host and the microbes. He is also interested in how environmental factors (such as diet and lifestyle) and historic processes impact the microbial communities in the gut and what consequences their effects have for the host. His research, which is inter-disciplinary and highly collaborative, has resulted in several publications on the evolution of the model gut symbiont Lactobacillus reuteri, the importance of environmental (diet) and host factors (host genotype) on the composition and functionality of the gut microbiota, and the impact of diet on gut microbial ecology in relation to health.”

As a regular reader you will appreciate my excitement in having Jens join our institution as we venture into studying the role that gut bugs may play in obesity.

On a personal note, the fact that Jens hails from Germany and we share an interest in music makes this recruitment even more attractive.

I certainly wish Jens all the best in his new position and look forward to future collaborations.

@DrSharma
Edmonton, AB

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Wednesday, April 16, 2014

Shame And Blame Has No Role In Addressing Obesity

Balancing the scales Kirk et alAs a regular reader you will be well aware of my recent excursions into the use of comedy to promote a better public understanding of obesity.

A very different (and I dare say more scientific) approach to harnessing the performing arts to promote a discourse on obesity is that taken by Sara Kirk and colleagues, Balancing The Scales, now described in a paper published in Qualitative Health Research.

Their approach is based on the recognition that,

“…individuals living with obesity are caught in the middle, facing judgment by society if they fail to manage their weight successfully and exposing themselves to health professionals who are unable to fully support them…if an individual is unable to make the changes prescribed for weight loss, resentment builds on both sides of the therapeutic relationship.”

This led Kirk and colleagues to extensively explore the issue of obesity from a variety of perspectives resulting in rather unique insights into similarities, differences, points of consensus, and tension associated with values, beliefs, perceptions, and practices among key stakeholders.

The 42 semistructured interviews were conducted in 22 individuals living with obesity, 4 policy makers, and 16 health professionals (8 dietitians, 4 family physicians, and 4 nurses).

Three major themes emerged from the analysis of the interviews:

Blame as a Devastating Relation of Power

“Individuals living with obesity shared feelings of shame and embarrassment with their inability to control their weight on their own. This blaming discourse can easily be seen in messages of “eat less, move more” promoted by health professionals, the health system, and wider society.”

“Individuals living with obesity spoke about the complexities of trying to lose weight, inclusive of cultural, social, and organizational barriers. Despite this insight, however, they placed the final explanation for their weight status on themselves and expressed immense feelings of guilt and shame.”

“All of the individuals living with obesity had tried multiple methods to manage their weight, with limited or no success. This was extremely frustrating for them and compounded their tendency, wholly or at least partially, to blame themselves for this perceived failure.”

“Similar to individuals living with obesity, health professionals struggled to understand the complexity of the issue, which often led to blaming the individual. Health professionals commented on the unrealistic expectations of people who wanted to lose weight quickly and how their role as a health professional could not possibly be supportive of this.”

“The health professionals we interviewed also blamed themselves for not having the answers, and described feeling ill-equipped to assist individuals to make successful changes.”

Tensions in Obesity Management and Prevention

“Both the individuals living with obesity and the health professionals did not feel supported by the health care system. Health professionals [and policy makers] also struggled to know how to approach the issue.”

“Individuals living with obesity also experienced exclusion when attempting to find appropriate support within the health care system. Most individuals in the study began to access this system when they believed they could no longer manage their weight by themselves.”

The Prevailing Medical Management Discourse

“Health professionals experienced many frustrations and contradictions in their experiences with obesity management, and at times questioned the notion of obesity as a disease. Being obese was often in itself not enough to receive health care. Health professionals in this study found it easier to work with individuals living with obesity when they also had another diagnosed chronic condition, such as diabetes or cardiovascular disease. They could then more confidently prescribe a specific treatment regime.”

As for policy makers,

“[One] policy maker questioned whether medical treatment for individuals living with obesity is necessary…. As an alternative to medicalizing obesity, the policy maker suggested addressing the issue of population health and using health promotion to support the majority of people who are not morbidly obese but are still struggling with weight problems.”

“Overall, individuals living with obesity sought validation for requiring support in a system that currently does not provide the support they need.”

Based on these findings, the authors note that,

“…our findings highlight the need to reframe the public debate on obesity. However, we suggest that rather than choosing one discourse over another (management vs. prevention; system vs. individual), we should engage aspects of both. This requires not only consideration of socioecological perspectives, but also a greater awareness among health professionals of the need to offer support, not advice.”

“Furthermore, relationships between patients and health care providers should be supportive (not blaming), recognizing the widespread prevalence of weight bias in society and working hard to challenge the stereotypes that dominate the discourse on body weight”

“It was also evident in the language and experiences provided by health care providers that training, resources, and support for weight management were a substantive part neither of their professional training nor of the health care system.”

To facilitate improved training of health professionals, the authors have developed the rich narratives obtained in this study into a dramatic presentation, depicting the relationship between a health professional and an individual living with obesity.

This narrative can be viewed here.

For interviews with the researchers – click here.

Clearly, it is work like this that is essential to understanding the current discourse (or rather lack of it) about obesity and finding strategies that do justice to those living with obesity.

There is simply no room for “shame and blame” in such a discourse.

@DrSharma
Edmonton, AB

ResearchBlogging.orgKirk SF, Price SL, Penney TL, Rehman L, Lyons RF, Piccinini-Vallis H, Vallis TM, Curran J, & Aston M (2014). Blame, Shame, and Lack of Support: A Multilevel Study on Obesity Management. Qualitative health research PMID: 24728109

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Thursday, April 10, 2014

Managing Weight Loss Expectations

sharma-obesity-great-expectationsWhile there are almost no limits to short-term weight loss goals (anyone can starve themselves thin) – the reality of long-term weight loss is rather sobering.

While diet and exercise generally provide an average long-term (3-5 years) sustainable weight loss or about 3-5% of initial weight, even bariatric surgery patients tend on average to sustain a weight loss of only 20-30% of their initial weight.

Surgery, although much safer than generally thought, still bears a risk of complications and the question is how much risk patients are willing to assume if they really knew and understood how much weight they are likely to lose with surgery.

This was the subject of a study by Christina Wee and colleagues, published in JAMA Surgery, in which they examined weight loss expectations and willingness to accept risk among patients seeking bariatric surgery.

The researchers interviews 650 patients interested in bariatric surgery at two bariatric centres in Boston.

On average, patients expected to lose as much as 38% of their weight after surgery and expressed disappointment if they did not lose at least 26%.

In fact, 40% of patients were unwilling to undergo a treatment that would result in only 20% weight loss.

Most patients (85%) accepted some risk of dying to undergo surgery, but the median acceptable risk was only 0.1%.

On the other hand, some patients (20%) appeared more desperate, willing to accept a risk of 10% or greater.

As one may expect, there were important gender differences in these findings: while women were more likely than men to be disappointed with a 20% weight loss, they were also less likely to accept a greater mortality risk.

An important finding for clinicians was that patients with lower quality-of-life scores and those who perceived needing to lose more than 10% and 20% of weight to achieve “any” health benefits were more likely to have unrealistic weight loss expectations.

This study not only shows that most patients seeking bariatric surgery have rather unrealistic weight loss expectations but also that   a substantial number may well be be disappointed with their weight loss after surgery.

It is also evident that many patients believe that they need to lose a rather substantial amount of weight to derive “ANY” health benefits, when in reality even rather modest (and certainly the average 20-30% weight loss seen with surgery) carries substantial health benefits for patients. (Many patients would in fact benefit substantially if they simply stopped gaining weight).

I certainly wonder what educational efforts may be necessary to align expectations with the clinical reality of bariatric surgery and whether better managing expectations is likely to alter current practice?

@DrSharma
Edmonton, AB

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Monday, April 7, 2014

The Molecular Mechanism of Sleeve Gastrectomy

sharma-obesity-verticalsleevegastrectomyIn recent year, vertical sleeve gastrectomy (VSG), which involves removing large parts of the stomach, thereby reducing it to the size of a small banana, has gained in popularity in bariatric surgery.

Although slightly less efficacious, it is a far simpler procedure to perform than the “classic” Roux-en-Y gastric bypass.

According to popular wisdom, the reason why VSG works has to do with mechanically reducing the volume of the stomach (thereby creating a physical “restriction”), whereby effect on gastric ghrelin secretion may or may not also play a role in reducing hunger (the science on this is somewhat unclear).

Now, a paper by Karen Ryan and colleagues from the University of Cincinnati, published in Nature, provides a completely new explanation for the molecular mechanism by which this surgery appears to work.

The study was prompted by the observation that VBG leads to profound changes in circulating bile acids. Bile acids are now known to bind to a nuclear receptor (farsenoid-X-receptor or FXR for short) which plays an important role in fat and glucose metabolism.

Using a rather elegant series of studies in mice, Ryan and colleagues demonstrate that the weight loss effect of sleeve gastrectomy has little to do with reducing the size of the stomach. Rather, almost all of its effect on body weight appears to be mediated by the effect of this surgery on circulating bile acids and accompanying changes in gut microbial flora.

The researchers also clearly demonstrate that much of the weight loss with SVG is dependent on a functional FXR, without which (as in FXR knockout mice) the surgery has little effect on body weight or glucose metabolism.

This demonstration of the importance of bile acids and FXR signalling as an important molecular mechanism for why VSG actually works is important because it means that this surgery could possibly be mimicked by pharmacological interventions that target bile acid and/or FXR.

In fact drugs that stimulate FXR (e.g. obeticholic acid) are already being considered for other indications including fatty liver disease and type 2 diabetes.

Given the remarkable efficacy of VSG surgery, the possibility of providing the same benefits in a pill are clearly attractive.

@DrSharma
Edmonton, AB

ResearchBlogging.orgRyan KK, Tremaroli V, Clemmensen C, Kovatcheva-Datchary P, Myronovych A, Karns R, Wilson-Pérez HE, Sandoval DA, Kohli R, Bäckhed F, & Seeley RJ (2014). FXR is a molecular target for the effects of vertical sleeve gastrectomy. Nature PMID: 24670636

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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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