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Do Hormones Play A Role in Weight Loss Failure After Bariatric Surgery?

>> Monday, November 18, 2013




Obesity surgery is currently the most effective treatment available for severe obesity.  While the smaller stomach reservoirs that are created by these surgeries play a major role in the weight loss seen, it is becoming increasingly evident that there are many other contributors at work, one of which is thought to be alterations in various hormone levels after surgery.

I was asked to write a review article discussing what we know about hormone changes in relation to weight loss failure and weight regain after bariatric surgery, which was recently published in the journal Gastroenterology Research and Practice.  In the article, I review eight of the key hormones thought to be involved in the weight changes after bariatric surgery (from GLP-1 to PYY to oxyntomodulin, bile acids, and others), as well as what we know about the hormone changes that occur after the four main types of bariatric surgery (gastric banding, sleeve gastrectomy, Roux-en-Y gastric bypass, and biliopancreatic diversion).

In summarizing what we know about hormonal associations with weight loss failure and weight regain after bariatric surgery, there was painfully little to discuss - there is unfortunately very little data in this area.

What became poignantly clear to me from compiling this review is that more research is desperately needed to help us understand how hormones may contribute to weight loss failure or regain after obesity surgery.  As I noted in the article,

In the future, with a better understanding
of this complex arena, assessment of hormone status
could potentially be helpful in understanding the hormonal
contributors to a patient’s postoperative weight loss failure
or recidivism, potentially aiding the clinician in utilizing
appropriate targeted hormone therapy to help them achieve
successful or sustained weight loss.

This is probably not a wish I should expect to see fulfilled anytime soon - after all, pinpointing hormonal predictors of weight regain after 'regular' dietary-induced weight loss has proven evasive as well.  However, with a dedicated body of bariatric researchers worldwide, I hope that we will learn more about this important area with time. 

Follow me on twitter! @drsuepedersen

www.drsue.ca © 2013

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Could Obesity Surgery Increase the Risk of Colon Cancer?

>> Sunday, September 29, 2013





As for any medical treatment or surgery, the decision to undergo bariatric surgery requires that the benefits and risks are carefully evaluated by the patient and the health care team.  Amongst the list of benefits, several studies have suggested that bariatric surgery decreases the risk of cancer amongst women.   Now, a new study suggests that the risk of colorectal cancer may actually be increased after obesity surgery.

The study was an evaluation of the population database in Sweden, looking at the colon cancer incidence rates amongst men and women who had obesity surgery (gastric bypass, gastric banding, and an older procedure called vertical banded gastroplasty), compared to patients with obesity who did not have bariatric surgery.  They found that amongst those who had had bariatric surgery, the risk of colon cancer was 60% higher than those who hadn't had surgery (though the absolute numbers were fairly low - 70 out of 15,095 patients, or 0.46% of patients who had obesity surgery developed colon cancer).  Ten years after bariatric surgery, the risk of having colon cancer was double compared to people with obesity who hadn't had bariatric surgery.

These results need to be taken with a grain of salt, as there are a number of limitations to this database analysis - for example, other risk factors associated with colon cancer such as smoking, diabetes, family history etc were not available (the interested reader can read more about this here).  The study does seem to contradict the overall protective effect that bariatric surgery is thought to have on cancer risk (for women, at least) - but then again, most previous studies have not followed up patients for as long as this one, and colon cancer is known to be a very slow growing tumor.

Following gastric bypass surgery, it has been suggested that the lining of the intestine may change (called 'mucosal hyperproliferation'), and an increase in a pro-tumor chemical has been found (a cytokine called 'macrophage migration inhibitory factor'), though other tumor inducing chemicals (such as TNF alpha and interleukin 6) have been shown to decrease after bariatric surgery.  The population of intestinal bacteria change after surgery as well, and there is still much we don't know about the effects of these changes (though there appear to be metabolic benefits of these post-surgery bacterial changes).

So where does this leave us?  Well, there are still many questions to be answered about the long term efffects of bariatric surgery, which only time will teach us.  In the meantime, we must continue to carefully weigh the benefits and risks of obesity surgery, and for patients who have had bariatric surgery, colon cancer screening and surveillance should be undertaken.

@drsuepedersen

www.drsue.ca © 2013

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Excess Skin After Bariatric Surgery

>> Saturday, May 4, 2013









On the second day of the Canadian Obesity Summit, I had the honor of being asked to act as a judge for a number of excellent research presentations during the poster session.  First, a heartfelt congratulations to all of the presenters - I was truly impressed by all of your efforts and studies, and I enjoyed each of our stimulating conversations!

A study that really struck a chord with me, and which I feel is really important to share, was a study looking at the impact of excess skin on physical activity in women who have had bariatric surgery.  The reason for doing this study is that over 70% of patients who have bariatric (obesity) surgery are left with excess skin that interferes with physical and social functioning. The research, conducted by A Baillot and colleagues at the University of Sherbrooke in Quebec, administered questionnaires to 26 women who had had bariatric (obesity) surgery at least 2 years prior, asking women about how their excess skin impacted them physically, psychologically, and socially.

They found that 77% of patients reported that their excess skin was making mobility during physical activity difficult, and that almost half were avoiding physical activity because of their excess skin.  What really hurt my heart was that when these women were asked why the excess skin caused them to avoid physical activity, the most common reason cited was that they were concerned about people staring at them (other reasons were hygiene concerns, weightiness of the excess skin, and a feeling of 'sloshing' of the skin).

My take home message from this study is that the likely development of excess skin after obesity surgery is something that needs to be discussed in detail with patients prior to having surgery, such that they are prepared for the physical, psychological, and social challenges that they may perceive or encounter.

And, as always, it is my hope that with education of our society, that any obesity related stigma that may exist out there will continue to decrease until it disappears entirely.  I was asked a lot at the summit as to why I blog - this reason would be amongst the highest.

Dr Sue Pedersen www.drsue.ca © 2013 

Follow me on Twitter for daily tips! @drsuepedersen

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Nutritional Support After Bariatric Surgery





Today, I would like to kowtow to my friend and colleague Dr Priya Manjoo, endocrinologist at the University of Victoria, who gave a fantastic talk about nutritional support of the bariatric patient at the Canadian Obesity Summit


I'll highlight a few of the key points here: 

1.  Prior to obesity surgery, many patients are already often deficient in nutrients; for example, one study showed that 65% of patients were deficient in vitamin D before surgery, and 27% were deficient in iron.  Therefore, it is imperative that these levels be checked and corrected before surgery is undertaken. 

2.   Following obesity surgery, there are a number of reasons why nutritional deficiencies can occur,  including insufficient intake due to dietary restrictions and food intolerances, anatomical causes due to changes made in the intestinal anatomy, and a disconnect between the timing of release of digestive enzymes and entry of food into the intestine. 

3.  Dr Manjoo then went through a fabulous review of the various vitamins and nutrients that we need to be on the watch for after bariatric surgery.  Adequate protein intake, and monitoring and supplementation (depending on the type of surgery) of calcium, vitamin D, iron, vitamin B12, folate, thiamine, zinc, copper, and selenium are all things that we need to think about.

Finally, as previously blogged, she pointed us towards the 2013 American Bariatric Guidelines for some guidance on this complex topic. 

Thanks Priya for a fabulous session!

Dr Sue Pedersen www.drsue.ca © 2013 

Follow me on Twitter for daily tips! @drsuepedersen

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New Bariatric Surgery Guidelines are Out!

>> Saturday, April 20, 2013






It's been an exciting few weeks - not only are the Canadian Diabetes Association 2013 guidelines out, but so too have the Clinical Practice Guidelines for Bariatric Surgery been updated!

These guidelines, published as a joint effort by the American Association of Clinical Endocrinologists, The Obesity Society, and the American Society for Metabolic & Bariatric Surgery, have some exciting new updates and features.

The guidelines address 7 key questions:

1.  Which patients should be offered bariatric surgery? 

2.  Whic bariatric surgical procedure should be offered? 

3.  How should potential candidates for bariatric surgery be managaed preoperatively? 

4.  What are the elements of medical clearance for bariatric surgery? 

5.  How can early postoperative care be optimized? 

6.  How can optimal follow-up of bariatric surgery be achieved? 

7.  What are the criteria for hospital admission after bariatric surgery?


A few headliners that caught my eye:

1.  Sleeve gastrectomy is no longer considered to be investigational; it is now considered to be a mainstream bariatric procedure. (though it has been 'unofficially' considered to be mainstream for some time already)

2.  Emerging data to suggest that bariatric surgery could be offered to patients with a BMI between 30-34.9 with diabetes or the metabolic syndrome, though the current evidence is limited by the small number of patients studied, and the lack of long term outcomes (so far).   See my previous comments on this issue here.

3.  There are excellent preoperative and postoperative checklists to help guide health care providers in terms of what needs to be asked about, checked for, and monitored.

The guidelines are a must-read for anyone involved in the care of bariatric patients.

Dr Sue Pedersen www.drsue.ca © 2013 

Follow me on Twitter for daily tips! @drsuepedersen

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Sex Drive, Fertility, and Bariatric Surgery

>> Wednesday, April 17, 2013





It is a well known fact that obesity is a risk factor for female infertility, and that fertility is often seen to improve after obesity surgery.  While it has been generally thought that improvements in various hormones after surgery are the reason for the improvement in fertility, a recent study suggests that it is not just about the physiology, but also the psychology.

The study, by Dr Legro and colleagues, included 29 women having gastric bypass surgery.  They looked at ovulation rates before and up to 2 years after gastric bypass surgery, and they also looked at responses to a questionnaire designed to assess sexual function.

Interestingly, they found that despite half of these women reporting irregular periods before surgery, 90% were actually ovulating before surgery.  While they did see some improvements in the hormonal parameters of the menstrual cycle after surgery, what was most impressive was the marked improvement in the sexual function questionnaire scores, with the biggest improvements seen in sexual desire and arousal.

It's important to note is that the group in this study was comprised of women who were relatively healthy obese women, so the ovulation rate may have been unusually high in this group.  However, the Bottom Line of the study is that improvements in sex drive and enjoyment may be a major factor in the improvement in fertility seen after gastric bypass surgery.

The most important thing to point out is that pregnancy MUST be avoided for 1-2 years after bariatric surgery (exact recommendation varies by clinic and country), due to concerns for fetal undernutrition and poor fetal growth as well as potential nutritional deficiencies.  Furthermore, there are concerns that the birth control pill may not be absorbed properly after bariatric surgery, and therefore, the pill MUST NOT be relied on for contraception.    Therefore, be sure to speak to your doctor about these issues before surgery, such that appropriate plans can be made to avoid pregnancy until it's safe to proceed.

Dr Sue Pedersen www.drsue.ca © 2013 

Follow me on Twitter for daily tips! @drsuepedersen

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Baseline Body Weight Does Not Predict Success of Bariatric Surgery

>> Monday, March 18, 2013








Currently, the critieria for who qualifies for bariatric surgery typically includes a body mass index (BMI) criterion - ie, a patient has to be at a certain body weight relative to their height to qualify for surgery.

A review of data to date on the landmark SOS trial was just published by L. Sjöstrom, which I encourage anyone interested in this field to read.  They have now followed SOS study patients for 20 years - though it's noted that many patients have dropped out of the study follow up along the way, so we do have to take the results with a large grain of salt.

While there are many results in this study that are very worthy of discussing, what I wanted to point out today is that the SOS study showed a benefit of obesity surgery to decrease the risk of death, diabetes, and cardiovascular disease, as well as a decreased risk of cancer in women. What is even more interesting is that the baseline BMI did NOT predict the effect of surgery on any of these endpoints.  (For those who download the article - see figure 7).  Interestingly, higher baseline insulin levels did predict favorable outcomes with regards to bariatric surgery decreasing the risk of death, cardiovascular disease, and diabetes (but not cancer).

This data therefore lends further evidence to the fact that BMI criteria should not be a fixed and fast rule for who qualifies for obesity surgery and who doesn't; looking at the whole patient and their metabolic profile (as always) is important!

Dr Sue Pedersen www.drsue.ca © 2013 

Follow me on Twitter for daily tips! @drsuepedersen

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