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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Friday, April 11, 2014

Does Eating More Protein Help Keep The Pounds Off?

sharma-obesity-diogeneslogoAs a regular reader, you may remember the DIOGENES trial, which studied the impact of different levels of protein intake on sustaining a weight-loss induced by eight weeks of a low-calorie formula diet (800 Kcal resulting in an average weight loss of about 11 Kg).

The original paper showed that individuals on a high-protein diet (providing 12 % more energy from protein that the low-protein diet) were about half as likely to discontinue the 26 week trial than those on a low-protein intake.

Now, a new paper from DIOGENES, published in the International Journal of Obesity, reports on the weight outcomes in participants, who were followed for up to 12 months in two of the participating centres (n=256).

The five ad libitum diets (no caloric restrictions) that followed the low-calorie diet (resulting in an average weight loss of about 11 Kg) were:

1) a low-protein and low-glycemic index diet,

2) a low-protein and high-glycemic-index diet,

3) a high-protein and low-glycemic-index diet,

4) a high-protein and high-glycemic-index diet,

5) a control diet.

While average weight regain over the 12-months was about 4 Kg (of the 11 Kg lost initially), the subjects on the high-protein diets kept off almost twice as much weight as those on the low-protien diets (glycemic index did not appear to make any significant difference).

Thus, the authors conclude that following a higher-protein ad libitum diet improves weight loss maintenance in overweight and obese adults over 12 months.

Clinicians may wish to stress the importance of maintaining a high-normal protein intake to clients trying to avoid regaining pounds that they have lost.

@DrSharma
Edmonton, AB

 

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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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Wednesday, April 9, 2014

Reserve Your Spot At The Obesity and Mental Health Conference, Toronto, May 14, 2014

smaller_CON_OMH_program_2014_2_Page_014614As a regular reader you may recall a previous conference on obesity and mental health which saw the release of the Toronto Charter on Obesity and Mental Health.

A follow up to this conference will be held in Toronto on May 14, 2014.

This time the focus is on clinical management of people with mental health issues presenting with weight gain as well as people with obesity presenting with mental health problems.

This one-day program features a rather distinguished roster of speakers, the full program can be downloaded here.

Registration for the conference is now open to all health professionals with an interest in obesity and/or mental health – click here

For more information on this conference – click here

@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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