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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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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Friday, April 4, 2014

Will Vitamin D Help You Lose Weight?

Vitamin D

Vitamin D

As a regular reader, you may well be aware of the discussions regarding a potential role of calcium and vitamin D in promoting weight loss.

Now, this issue was examined by Mason and colleagues in a 12 month randomised controlled trial, published in the American Journal of Clinical Nutrition.

The study involved 218 overweight/obese women (50-75 y of age) with moderate vitamin D deficiency (serum 25-hydroxyvitamin D [25(OH)D] ≥10 ng/mL but

The weight-loss intervention included a reduced-calorie diet (10% weight loss goal) and 225 min/wk of moderate-to-vigorous aerobic activity.

A total of 86% of participants completed the 12-mo measurements losing on average about 7 Kg, with no significant differences between the two groups.

There were also no significant differences in the reduction in BMI, waist circumference, percentage body fat, trunk fat, insulin or CRP levels.

At best, there was a slight trend towards greater benefits in women, who became replete with vitamin D supplementation compared to those who did not.

Thus, in summary, simply adding vitamin D to a weight loss regimen does little (if anything) to aid weight loss.

This is not to say that vitamin D supplementation in people with vitamin D deficiency may not be a good thing – it just does not appear to have much effect on body weight.

@DrSharma
Halifax, NS

ResearchBlogging.orgMason C, Xiao L, Imayama I, Duggan C, Wang CY, Korde L, & McTiernan A (2014). Vitamin D3 supplementation during weight loss: a double-blind randomized controlled trial. The American journal of clinical nutrition PMID: 24622804

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Tuesday, April 1, 2014

Dr. Oz’s Next Miracle Obesity Cure: Ginger?

ginger-health-benefits-usesA recent article in Forbes Magazine noted at least 16 nonsensical “weight-loss miracles” discovered by Dr. Oz.

Well, allow me to be the first to predict another weight-loss miacle that may soon make the airwaves (or rather your cable): ginger.

And this would by no means be a surprise given that Saravanan and colleagues from Tamil Nadu, India, in a paper published in the Journal of the Science of Food and Agriculture, note the anti-obesity effects of ginger, especially in the face of a high-fat diet.

Unfortunately (not that Dr. Oz would care), this finding was in rats, who were given varying amounts of gingerol for 30 days.

And indeed, at the highest dose (75 mg/Kg), animals did have lower glucose level, body weight, leptin, insulin, amylase, lipase plasma and tissue lipids when compared to controls.

As the authors show, this was about as much of an effect as seen in animals treated with lorcaserin, an anti-obesity drug recently approved by the FDA.

While, to their credit, the authors make only generically optimistic claims as to the use of these findings rather than proclaim  another “weight-loss miracle”, they also fail to tell us exactly how many kilograms of fresh ginger (or even ginger extract) one would have to eat every day to come anywhere close to reaching an effective dose of gingerol.

Never mind that we also have no idea how such a dose would be tolerated in humans (yes, natural products have side effects!), or even whether or not ginger would in fact have any similar effects on body weight or metabolism in humans.

Surely, there is nothing wrong with this line of research. Many medical discoveries (e.g. aspirin) were made through the isolation of pharmacologically active moieties from plants.

What is wrong, however, is when such basic findings are overhyped and presented as “miracles” with claims of curing everything from obesity and heart disease to cancer and Alzheimer’s (surprisingly such claims often fail to include world peace).

Will Dr. Oz pick up on ginger? I don’t know. But if he does, remember you heard it here first.

@DrSharma
Edmonton, AB

ResearchBlogging.orgSaravanan G, Ponmurugan P, Deepa MA, & Senthilkumar B (2014). Antiobesity action of gingerol: Effect on lipid profile, insulin, leptin, amylase and lipase on male obese rats induced by a high-fat diet. Journal of the science of food and agriculture PMID: 24615565

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Thursday, March 27, 2014

Three Essential Ways in Which Melatonin Links to Energy Balance

sharma-obesity-pineal-glandAs a regular reader, you will be quite familiar with the emerging recognition of sleep (or rather lack thereof) as an important determinant of weight gain.

Melatonin, an evolutionary ancient molecule that, in mammals, is secreted from the pineal gland, is a hormone that plays a major role as a key regulator of the circadian cycle, along which  virtually all metabolic activities are coordinated.

A paper by José Cipolla-Neto and colleagues, published in the Journal of Pineal Research, provides a fascinating overview of how melatonin plays a significant role in energy metabolism.

Its first role relates to insulin secretion and action. Thus, melatonin is not only necessary for the proper synthesis and secretion of insulin, it also plays a role in the insulin-signalling pathway through its effects on GLUT4 receptors.

Secondly, as a powerful chronobiotic, it helps coordinate various metabolic processes so that the activity/feeding phase of the day is associated with higher insulin sensitivity whereas the rest/fasting phase is synchronized to lower insulin sensitivity.

Thirdly, melatonin plays an important role in regulating energy flow to and from fat stores and directly regulating the energy expenditure through the activation of brown adipose tissue and participating in the browning process of white adipose tissue.

The paper discusses how the reduction in melatonin production, as seen during aging, shift-work or night-time light exposure can induce insulin resistance, glucose intolerance, sleep disturbance and metabolic circadian disorganization, which together can lead to weigh gain.

Thus, the available data supports the notion that melatonin replacement therapy may provide a novel strategy to influence metabolism, at least in people with disruptions in their melatonin system.

Clearly, these notions need to be tested in well-controlled randomised trials but there certainly appears to be ample data to suggest that such a trial may well be worthwhile.

If you have taken melatonin or prescribed it to your patients, I’d certainly like to hear about your experience.

@DrSharma
Edmonton, AB

Hat tip to Sukie for pointing me to this article.

ResearchBlogging.orgCipolla-Neto J, Amaral FG, Afeche SC, Tan DX, & Reiter RJ (2014). Melatonin, Energy Metabolism and Obesity: a Review. Journal of pineal research PMID: 24654916

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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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