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Does Gastric Bypass Surgery Increase Energy Burn?

>> Thursday, September 10, 2015






We know that Roux-en-Y gastric bypass surgery is effective to induce weight loss, causing an average weight loss of about 40% of total body weight.  How this actually happens is still far from completely understood.   Many mechanisms are likely at play, but one of the most hotly debated is whether energy burn (called energy expenditure) goes up, down, or does not change after gastric bypass surgery.

We have recently published the results of our randomized, controlled clinical trial in gastric bypass patients, to add to our understanding of this complex area.

In this trial, conducted at the University of Copenhagen and published in the International Journal of Obesity, we enrolled 28 patients, and placed them on a low calorie diet (1000 kcal/day) in preparation for their gastric bypass surgery.  Patients were randomized to have surgery either 8 weeks or 12 weeks after the start of the low calorie diet, such that we could compare them just before the second group had surgery.  (This protocol enabled us to use a 'pair-fed' control model, as there have been criticisms of other studies comparing post surgical patients to control groups who are eating totally differently, not on a low calorie diet, and not on a negative weight trajectory.)  We then repeated testing on the entire group at 1.5 years post surgery.

We found that at 3 weeks postoperatively, patients had lower body composition-adjusted 24 hour and basal energy expenditure compared to those who had not yet had their surgery.  However, at the 1.5 year mark, patients' energy expenditure was not different compared to their own preoperative values.   We also found that surgery increased the postprandial response to many hormones, including GLP-1, PYY, bile acids, and FGF-19.  Decreases in appetite were particularly associated with increased GLP-1, increased PYY, and decreased ghrelin.

So, our study suggests that the decrease in weight seen after gastric bypass surgery is not caused by an increase in energy expenditure, but that weight loss is more likely to be mediated by hormonally-induced changes in appetite.

An enormous and heartfelt thank you to my ex-PhD student (now postdoc!) Dr Julie Berg Schmidt, and all of my dear colleagues at the University of Copenhagen, for years of fantastic collaboration to bring this study to fruition!  Stay tuned for many more publications stemming from this trial.


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www.drsue.ca © 2015

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Could Bariatric Surgery Cure My Diabetes?

>> Sunday, September 6, 2015




Clinicians out there – have you ever been asked this question?

I get asked this question at least once a day.

There is an expanding body of data demonstrating the powerful ability of bariatric surgery to improve control of type 2 diabetes, and even put it into remission.  However, we are lacking in long term data on this important topic, with most higher quality data only being available to 2 years post surgery For the first time, we now have data from a randomized clinical trial to tell us a little more about what happens to patients with type 2 diabetes, 5 years after bariatric surgery. (Skip to 'So, my take on this?' below if you don't want the study details)

The study, published this week in The Lancet by Mingrone and colleagues, randomized 60 patients to receive either gastric bypass surgery (n=20), biliopancreatic diversion (BPD, n=20), or medical treatment (n=20) for their type 2 diabetes.  Participants were age 30-60, and had to have type 2 diabetes for at least 5 years.  Almost half of the patients in the study were using insulin as part of their diabetes treatment 

The key findings of the study were:
  • ·             At 5 years after surgery, 37% of patients who had gastric bypass, 73% of patients who had BPD, and none of the patients in the medical treatment group, were in remission from their diabetes.
  • ·             About half of patients who achieved diabetes remission at 2 years, had relapsed by 5 years (in other words, their diabetes came back). However, when their diabetes came back, it required less medication and was under better control than before the surgery.
  • ·             Amount of weight lost did not predict who would go into diabetes remission (or who would relapse).
  • ·             Cardiovascular risk (defined as a composite endpoint of at least 2 parameters including reduction in heart/diabetes drugs and improvement in diabetes, cholesterol, or blood pressure control) decreased more in surgically treated groups.
  • ·             Five major diabetes complications were seen in patients in the medical group, vs one in the gastric bypass group and none in the BPD group.


So, my take on this? These findings support what we have seen in previous nonrandomized 5 year data: bariatric surgery can be quite powerful to put diabetes into remission (with variable effect depending on the type of surgery), but by 5 years, about half of the diabetes cases come back.  This is a small study, but kudos to the study authors, as I know from my own experiences that it is very difficult to conduct randomized controlled clinical trials in this area.  That the amount of weight loss did not predict the effect of the surgery on diabetes reminds us of the powerful impact of other mechanisms of these surgeries on blood glucose control (for example, changes in gut hormone production).

It’s important to note that while diabetes complications were lower in the surgery group, the surgical and surgically related metabolic complications were (of course) higher in the surgical groups.  These risks were highest in the BPD group, which is a rather dramatic and extensive intestinal bypass procedure.  BPD is not accepted as a standard surgery due to the risk of complications, and in most places BPD is only available in a research setting.

Bariatric surgery can be a powerful and effective treatment for type 2 diabetes for the right individual, who is comfortable with the risk vs benefit profile of surgery, and for whom the benefits clearly exceed the risks.  Patients who experience remission of their diabetes after surgery need to be followed lifelong, as the diabetes can certainly come back.

Follow me on twitter! @drsuepedersen

www.drsue.ca © 2015

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Obesity Management In Canada - A Long (But Promising!) Road Ahead

>> Saturday, May 2, 2015




At this week's Canadian Obesity Summit meeting, I have had the great pleasure of chairing, speaking, and participating in a diverse array of educational sessions, ranging from studies of lifestyle alterations, to government policies, to medications treating obesity, to bariatric surgery.

One of the themes that rang strong is this:

Canada needs more resources dedicated to the management of obesity. 

I can give you many examples of how this point came out, but I'll give you one that rings out in particular.  One session which discussed bariatric surgery included a fabulous presentation by bariatric surgeon, Dr Mary-Anne Aarts, regarding barriers to post operative follow up of bariatric patients.  An interesting discussion ensued with comments from bariatric care providers across the country, and most agreed that follow up appointment attendance is often not good, particularly the further a patient gets in their post op journey (after 6 months post surgery, patients are usually requested to come to appointments every 6 months until 2 years post op).   One point that was made was that follow up may be perhaps too infrequent to keep patients interested and motivated to continue to come. (Studies do show that bariatric surgery patients enjoy greater success with more frequent follow up.)  Dr Aarts pointed out that in the Netherlands, bariatric patients have appointments scheduled every 3 months for 2 years postoperatively, which shocked most of the audience... who in Canada has the resources for that?!  

Here is our problem.  Obesity is a chronic disease, just like, for example, diabetes - yet, we don't treat obesity like a chronic disease.  The Canadian Diabetes Guidelines recommend that diabetics see a physician every 3 months at least, to have an A1C (diabetes report card) and other elements of their health checked as needed.  Why don't we have the same resources available to treat obesity in the same long term, longitudinal way?  If we asked our patients with obesity to follow up every 3 months with a health care provider on an ongoing basis to help them manage this disease, perhaps they might feel more supported and weight management success might be better.

What we need is to:

1.  Break down the stigma against obesity amongst the general public and health care providers, such that obesity is accepted as a chronic disease and not a lifestyle problem.

2.  Have more resources available in health care such that we are able to manage obesity with a long term, team based approach that engages multiple disciplines including dietitians, nurses, pharmacists, psychologists, exercise therapists, and doctors.

3.  Teach health care providers how to best approach the discussion and treatment of obesity with their patients. (See the 5As of obesity as a great way to start!)


So what's the 'Promising' part in all of this?   We (as the Canadian Obesity Network) are 11,000 members strong, and passionately dedicated to achieving these goals.  Together, we continue to make a difference one step at a time, with the above goals in mind.   This week's Summit has gone a long way to breaking down the obesity stigma in the public eye, and we continue to redouble our efforts as our numbers and voice grow.

PS - the Canadian Obesity Network membership is open to anyone with a professional stake in obesity - and it's totally free to join!  Check it out here!

Looking forward to the last day of the Summit today.


Follow me on twitter! @drsuepedersen

www.drsue.ca © 2015

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Why Weight Loss Increases Gallstone Risk

>> Sunday, April 19, 2015





As for everything in life, weight loss too has its pros and cons.  While the health benefits of weight loss are numerous and powerful, there is an increased risk of gallstone formation, particularly if the weight loss is fast.

Gallstones are very common, being present in 17% of women and 8% of men (most don't know that they have them!).  Bile, which is the digestive juice made by the liver and stored in the gallbladder, is composed of bile acids, which are made by the liver from cholesterol.  Bile also contains cholesterol, phospholipids, proteins and electrolytes.  The bile is usually able to carry cholesterol produced by the liver out into the intestine in a liquid form, but if the cholesterol concentration gets too high, or the contraction of the gallbladder gets too sluggish, cholesterol crystals develop and gallstones form.

Obesity is a risk factor for gallstones for a number of reasons.  There is a larger pool of cholesterol moving around in the body, and the liver's ability to convert cholesterol into bile acids is impaired (thus, more cholesterol relative to bile acids in the bile).   Gallbladder contractions are also more sluggish in obesity, which may be related to insulin resistance and resistance to a satiety (sense of fullness) hormone called leptin.  Diabetes, prediabetes, use of the birth control pill, and hormone replacement therapy are other risk factors for gallstone disease.  Genetics also play a part in gallstone risk, which is an area that we are just starting to learn about.

Within the first 4 months of moderate weight loss on a diet, the risk of gallstones is as high as 25% (though most of these will be without symptoms).  With faster and larger weight loss, the risk is higher: as many as 71% of patients will have gallstone formation by 1 year after bariatric (obesity) surgery.  About 40% of people developing gallstones after bariatric surgery will have symptoms; for those who don't have symptoms, about half will disappear by 2 years after surgery.

Gallstones form during weight loss because cholesterol content of bile increases during weight loss, as fats are being moved out of fat tissue and being utilized or disposed of by the body.  If calorie intake is too low, bile acid production by the liver may drop as well.  Also, during rapid weight loss, the gallbladder contractions become more sluggish.

So, what are the take home messages here?  Again, remember that the health benefits of weight loss are great and numerous, and far outweigh the potential risk of gallstone formation.  That being said, losing weight at a reasonable rate (max 1-2 lb per week) helps to prevent the higher risk of gallstones that comes with too rapid a rate of weight loss.  For those who will be losing weight quickly with bariatric surgery, your surgeon may recommend that your gallbladder be removed at the time of surgery if you already have gallstones.  If not, a medication called URSO (ursodeoxycholic acid) may be recommended, which has been shown to reduce the risk of gallstone formation after gastric bypass surgery by 60%.

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www.drsue.ca © 2015

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Bariatric Surgery For Diabetes Prevention?

>> Wednesday, March 11, 2015







Over the last decades, many modalities to prevent type 2 diabetes have been studied.  Lifestyle changes, particularly if they result in weight loss, can be very powerful to prevent this condition.  Of all of the medications studied, only metformin has so far been recommended to decrease the risk of developing diabetes in people who have prediabetes.  Now, studies are coming out, showing that bariatric (obesity) surgery can be very powerful to prevent type 2 diabetes.

One such study, published recently in The Lancet (Diabetes & Endocrinology),  looked at over 2000 patients who had bariatric surgery, and compared them to a group of matched patients who had not had obesity surgery.  They found that, over a median of 2.8 years and a maximum of 7 years of follow up, patients who had bariatric surgery had an 80% lower risk of developing diabetes compared to people who had not had bariatric surgery.

Another recent study was a systemic review and meta-analysis that looked at the power of different interventions to prevent diabetes. In examination of studies of physical activity +/- diet, anti diabetic medications, obesity medications, and bariatric surgery, they found all of these strategies to be of benefit.  Bariatric surgery stood out as being the most effective to prevent diabetes, with a 90% reduction in risk.

So the question then becomes, should we advocate for obesity surgery for the purpose of prevention of diabetes?  Well, as for any treatment or prevention of any medical condition, it's important to balance the benefits vs risks.  Bariatric surgery is invasive, and the most successful modalities (gastric bypass and sleeve gastrectomy) are permanent procedures.  These procedures have a long list of possible complications that need to be taken into consideration.

While bariatric surgery may be the best treatment option for some patients with obesity and existing type 2 diabetes, obstructive sleep apnea, severe high blood pressure, or severe osteoarthritis, it seems that using surgery solely to prevent these conditions may be outweighed by potential risks.  That being said, a marked reduction in risk of developing type 2 diabetes is certainly an added bonus to the patient having bariatric surgery who is having bariatric surgery for other reasons.


Thanks to my friend Gord for the inspiration for this blog post!

Follow me on twitter! @drsuepedersen

www.drsue.ca © 2015

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