Bariatric Surgery and Bone Health

The decision to undergo obesity (bariatric) surgery is a complex one, as the potential benefits and potential risks are many.  A longterm potential complication that is often overlooked is the effect that bariatric surgery can have on bones.


As outlined in an excellent review by Brzozowska and colleagues, the effect of bariatric surgery on bone health is not well understood.  As the potential effects, as well as what we know (and don't) is quite variable depending on what type of bariatric surgery is performed, here are a few notes organized by procedure:  (you can also read more about the procedures in general here)

Gastric Bypass Surgery:  We know that gastric bypass alters bone metabolism in favor of bone breakdown.  In many cases, this is at least partially due to vitamin D and/or calcium deficiency - both require supplementation lifelong after gastric bypass, and inadequate replacement will cause bone depletion over time.  There are many other factors involved as well - several hormones made in the fat tissue and the gut that change after gastric bypass surgery have been implicated in changes in bone metabolism as well.

Sleeve Gastrectomy:  As a newer procedure, very little is known about the effect of sleeve gastrectomy on bone.  The available data suggests that sleeves do affect bone metabolism and can cause bone loss over time.

Gastric Banding:  It is not known whether gastric banding has an adverse effect on bones or not - studies done so far have shown conflicting results.  Gastric banding is a less invasive procedure that doesn't cause calcium or vitamin D deficiency, and doesn't cause as many hormonal changes as the other two surgeries.  (That being said, gastric banding is falling out of favor due to its poor longterm efficacy and high reoperation rates over the long term.)

A few important caveats to the above discussion:

1.  It is not known whether changes in bone metabolism seen with bariatric surgery result in an increase in fracture risk - more study is needed.

2.  The long term effect on bone metabolism is not known, as most studies done to date are only a year or two in duration.  Longer term studies will help us to understand the effect on long term fracture risk as well, which is the most important outcome measure.

3.  The effect on bones may be different not only by the type of surgical procedure, but also by age and gender - again, more study is needed.

The Bottom Line: Anyone having bariatric surgery should have a baseline bone density done before surgery, and bone density should be monitored after surgery as well (guidelines are available here).   While adequate calcium and vitamin D is an important component of bone health, there is much more about the effects of bariatric surgery on bone that we still don't understand.


Dr Sue Pedersen www.drsue.ca © 2012 

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Struggles With Weight or Cholesterol? Turn Off Your Light at Night!

It is a well known fact that not getting enough sleep is a risk factor for obesity.  However, if you think you ARE one of the lucky ones who actually does get enough sleep, ask yourself if you are getting enough sleep in darkness?  A new study suggests that people who are exposed to light at night (even if they are sleeping) may be at an increased risk of carrying extra body weight, and even of having higher cholesterol!

The study, published in the current issue of the Journal of Clinical Endocrinology and Metabolism, examined body weight and cholesterol levels amongst older people (average age 73) in Japan.  Researchers went into participants' homes and recorded exposure to light overnight, and found that those who are exposed to light overnight were 89% more likely to be obese, and 72% more likely to have cholesterol problems, compared to those who sleep in the dark.  

While this study needs to be repeated in a younger population to know if these findings hold true outside of older age, there is already lots of evidence that sleep deprivation increases the risk of obesity, and that blue light exposure in particular (including from computer and mobile device screens) makes it harder to fall asleep - a habit that is particularly relevant for younger generations.


The Bottom Line:  Lights Out!

Dr Sue Pedersen www.drsue.ca © 2012 

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New Data on Type 2 Diabetes and Obesity Surgery

At the European Association for the Study of Diabetes (EASD) meeting in Berlin today, I had the pleasure of sitting in on a session discussing the effects of obesity surgery on type 2 diabetes.  Whereas previous years of diabetes meetings have seen very sparse attendance at bariatric surgery talks, this session was absolutely packed. 

At this session, a number of fascinating studies were
presented.  Highlights included: (be warned - it's a very science-heavy blog this week!)

A study by S. Steven and colleagues (UK) looked at a group of 92
patients who had type 2 diabetes prior to having gastric bypass
surgery, with the aim of determining which factors were associated
with a greater chance of diabetes remission after surgery. One of
their findings was that the degree of weight loss achieved post op was
the main determinant of diabetes remission - controversial, as the
bulk of currently available evidence suggests that remission of
diabetes is independent of weight lost.

A study by Pournaras and colleagues found that a nifty removable liner placed
inside of the first 60cm of small intestine (called a duodenal-jejunal
bypass liner) improved type 2 diabetes control over a 1 year trial period.
This introduces the question as to whether, in the future, we can
consider less invasive alternatives to bariatric surgery (such as
these) to help control type 2 diabetes.


A couple of elegant studies out of Denmark (including colleagues Jens Juul Holst and Sten Madsbad who I collaborate with on research studies personally) and Sweden were presented, designed to give us a better understanding of just how obesity surgery improves type 2 diabetes (with a lot of arrows pointing to the increase in the hormone GLP-1 that is seen after surgery).

Finally, there was a neat study from Finland showing that the insulin resistance of fat in femoral bone marrow improves with bariatric surgery (I personally had not previously thought about bone marrow being insulin resistant!).  

Overall, a very exciting day, and a very exciting meeting!

Dr Sue Pedersen www.drsue.ca © 2012 drsuetalks@gmail.com

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Sweeteners - Friend or Foe?

Artificial sweeteners have long been available, as a way to sweeten drinks and food while avoiding the calorie impact of sugar.  Recently, sweeteners have been on the hot seat, as it has been questioned whether these chemicals are friend or foe in the battle of the bulge.


There are several sweeteners currently available (as blogged previously), and the first thing that bears saying is that each of these chemicals is a very different compound, so the effects of each one could be different.   (to jump over the scientific part of this discussion, skip to The Bottom Line below)

Interestingly, in recent years, we have learned that sweeteners can activate not only the sweet receptors in our mouths, but also in our intestines and our pancreas (though it's only the receptors in our mouths that give us the feeling of eating something sweet).  It has therefore been suggested that artificial sweeteners may have an effect on the production of appetite regulating hormones, leading to weight gain.

As recently reviewed, some 'test tube' (in vitro) studies have shown that artificial sweeteners can affect the production of appetite hormones from gut cells, while other test tube studies have shown no effect.  In human and animal studies, most have NOT shown an effect of sweeteners on appetite hormones.  Thus, overall, the research suggests that sweeteners do not have an effect on appetite - though the research is far from complete, and there is still a lot of ongoing study in this area. 

In addition, several studies have shown that a higher consumption of sweeteners is linked with a higher risk of obesity.  However, what these studies are not able to separate is whether higher sweetener consumption is seen in people who are overweight because they are drinking the sweeteners in an attempt to lose the weight, or whether the sweeteners are actually causing the weight struggle.   There is much research being actively done in the area to give us an answer to this question.

The Bottom Line: As it stands now, there is not enough evidence to convince us that sweeteners lead to weight gain, while the evidence that excess sugar leads to weight gain is very clear.  There are many excellent clinical trials underway in this area, which will hopefully give us more clarity on the subject.

Dr Sue Pedersen www.drsue.ca © 2012 drsuetalks@gmail.com

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Bisphenol A Exposure from Canned Soup

There is mounting evidence that exposure to a widely used chemical called bisphenol A is associated with an increased risk of obesity, diabetes, and metabolic syndrome.  A recent study reveals that eating canned soup for just 5 days can dramatically increase exposure to this potentially dangerous chemical.

Bisphenol A is a widely used chemical, found in a variety of products ranging from plastics to cash register receipts.  Most of our exposure is thought to be through food; in addition to being present in many water bottles and plastic food storage containers, it is also present in the interior epoxy coatings of many canned goods used to prevent corrosion.

The study was eloquently simple.  Seventy-five students and staff at the Harvard School of Public Health were each asked to eat soup for lunch for 5 consecutive days, and were randomly assigned to eating either canned soup, versus homemade soup from scratch. The following week, they ate soup each day for lunch once again, but they ate the opposite kind of soup from what they had eaten the week previously (researchers: thereby providing a randomized, single blinded, crossover design). 

The results were, in my opinion, quite astonishing: the researchers found that the bisphenol A levels in the urine were nearly twenty times higher after a week of canned soup consumption, compared to after homemade soup consumption.  Further, the urine bisphenol A levels after the canned food week were 60% higher than the higher end of urine bisphenol A levels noted in the general population. 

The study did not test the bisphenol A levels in the blood, so we don’t know if these people quickly cleared the bisphenol A from their systems, or whether the bisphenol A levels in their blood or other tissues was also elevated, or for how long.  That being said, the study does clearly show that just 5 days of eating canned soup dramatically increases exposure to this potentially harmful compound. 

Let’s hope that this study gives an extra push towards using bisphenol A – free linings to canned goods, as well as yet another reason to cook and enjoy healthy food made at home!  

Thanks to my friend and colleague Jon for pointing out this study!

Dr Sue Pedersen www.drsue.ca © 2012

drsuetalks@gmail.com 

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Abuse in Childhood Increases Risk of Obesity in Adulthood

The struggle with weight is very complex, and goes so much deeper than simply a balance between calories in and calories out. For many people, there is an emotional contributor to the weight struggle, and for some, a history of abuse in their childhood.

An ongoing study called the ACE (Adverse Childhood Experiences) study has done much to educate us on the important relationship between childhood abuse and obesity later in life.  This study, which includes data from over 17,000 people, is one of the largest studies ever conducted to help us understand the associations between childhood maltreatment, and health and wellbeing later in life.

The obesity substudy surveyed adults by mail about their first 18 years of life, and looked for associations between their answers and their body weight as adults.

An alarming two thirds of the study population reported some sort of abuse during their childhood years.  Physical and verbal abuse were most strongly associated with obesity.  People who reported being 'often hit and injured' had a 40% increased risk of obesity.  Furthermore, the risk of obesity was higher with the number of different types, and severity, of abuse.

This study shows us that some people's struggles with obesity may be deeply rooted in a history of abuse in their childhood.  It is of the utmost importance for health care providers to do everything they can to help people identify, understand, and manage these complex and serious issues.

Taken as a whole, the ACE study suggest that certain childhood experiences such as abuse, neglect, and family dysfunction are risk factors for several illnesses as well as poor quality of life.  The ACE study is still ongoing, and is now looking at the relationship between these childhood experiences, the use of health care resources, and causes of death.

As the ACE study website notes: Progress in preventing and recovering from the nation's worst health and social problems is likely to benefit from understanding that many of these problems arise as a consequence of adverse childhood experiences.

Thank you to my friend and colleague, Margaret, for bringing this important study to my attention.

Dr Sue Pedersen www.drsue.ca © 2012 drsuetalks@gmail.com

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Blue Light From Your Electronic Device - Keeping You Up At Night?

Most of us have one, and most of us do it - we use our computers, iPhones, tablets, and other devices until right before sleep. Heck, most of us bring them into the bedroom with us (it's our alarm clock too, right?).  If you are a person who struggles to get to sleep, rethink your actions - the blue light emitted from these devices may be making it harder for you to fall asleep.

Blue light is part of the spectrum of normal light, and it's abundantly emitted from the screen of your computer and your portable device.  Blue light stimulates a special sensor in our eyes called melanopsin, which is thought to regulate our sense of night and day by affecting levels of melatonin (a sleep hormone) in our brains.  When we see blue light, melanopsin is stimulated, which suppresses melatonin levels, effectively telling our brains that it is daytime and not the time to sleep.  So, if you're using your electronic device before bed, it may take a while after you shut it off for your brain to realize it's night time and fall asleep.

The makers of these devices are hard at work to develop features that limit the amount of blue light emitted from screens at night.  For iPad and iPhone users, you can dim the screen in the Settings menu, which helps to decrease the overall (and therefore also the blue) light emitted.  There are also funky orange tinted glasses and screen filters available out there that help to decrease the amount of blue light you see, and even computer software that can be installed to decrease the amount of blue light coming from your screen.

Knowing that sleep deprivation increases the risk of obesity, here's one more item we can add to the long list of contributors to weight struggles in modern society.

Not to mention that reading those palpitation-inducing work emails right before bed probably isn't the best idea, either. :)

Dr Sue Pedersen www.drsue.ca © 2012 drsuetalks@gmail.com

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Dangers of Herbal Remedies

Many people take some form of naturopathic or alternative remedy for a wide variety of reasons - a whopping $14.8 BILLION has been spent in the United States on herbal remedies in a single year.  For most people, it's the idea that the product is 'natural' that is attractive - it makes it seem as though these substances can only do good, and can do no harm.  Be warned - it is due to the unfortunate lack of regulation of these products that this 'do no harm' idea has been successfully disseminated - but it is not true at all.

As nicely summarized in a recent article which I highly encourage you to read, dietary supplements are exempt from the usual medication regulation by the American FDA.  This means that a product does not have to be proven effective or safe before it is put on the market.  The only information we have about potential side effects of a herbal remedy is from voluntary reporting after the product is in use, which only represents a small fraction of the side effects that are happening but not being reported.

As an example from the world of herbal treatments of obesity, the article notes:

Even when the agency identifies an unsafe product, it lacks authority to mandate its removal from the market because it must meet the very high legal requirement to demonstrate “significant or unreasonable” risk. That is why it took the FDA more than 10 years to remove from the market ephedra-containing herbal weight-loss products that had caused hundreds of deaths and thousands of adverse events.   


Other problems that limit the ability to understand these chemicals and herbs include:

• Inadequate labeling of the supplement - in other words, it's not clear exactly what the product contains. 
• Frequent unsound and illegal claims made by websites - a study investigating this found that staff at retail outlets have even been caught telling patients to take their herbs instead of prescription medications - which could have life threatening consequences.
• Herbal remedies can be tainted with undeclared prescription drugs and heavy metals - as noted in the recent article - “These tainted products can cause serious adverse events, including strokes, organ failure and death.”

The internet and TV media tend to overblow the potential benefits and downplay potential harms of herbal supplements, while the reverse publicity is true for prescription medications.  As such, many people have a trust in herbal remedies that they don't have for prescription medications. 

The bottom line is that just like for a prescription medication, the decision to take a herbal remedy should be made with a careful evaluation of the benfits vs the risks.  The unfortunate reality is that this information for naturopathic remedies is just not available, so it's impossible to make this assessment.  

The only solution to this problem is much stricter regulation of these substances, with careful evaluation of their benefits vs risks, before they are put on shelves.  The FDA has recently issued a draft proposal to gain authority to regulate supplements - let's hope that this goes through.  

As a final note - the beautiful, naturally occuring plant pictured above is the digitalis plant.  The extract from this plant (also called Digoxin) is a cardiovascular drug that is used to treat certain heart problems.  When digoxin is prescribed to patients, levels are monitored very carefully, as high levels can cause very dangerous side effects, including heart rhythm disturbances, which can be life threatening.  This example reminds us that just because a substance is natural, does not mean that it is free of possible side effects.

Dr Sue Pedersen www.drsue.ca © 2012 drsuetalks@gmail.com

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Colored Potato Chips Curb Snacking

I'm pretty sure that most of us have had that experience where we open a package of our favorite (insert: candy, chips, chocolate) for a little taste... and the next thing you know, it's gone!  In an effort to discover ways to help us curb our snacking habits, researchers have discovered that inserting the occasional red potato chip into a stack of regular chips helped to curb snack size by over 50%!

The study, just published in the journal Health Psychology, asked a group of American undergraduate students to eat chips from a tube while watching a movie.  Red chips were inserted at regular intervals (eg every 5th chip) in one group, with no red chips in the tubes of the other group.

They found that when red chips were inserted, the number of chips consumed was reduced by more than 50%.  Further, when participants were asked how much they ate, they were more accurate in their estimates when the red chips were inserted, compared to when there were no red chips inserted.  

So what does this teach us?  It seems that having a natural 'break' in a snack, in this case created by a different color, helps us to curb our portions.  This may be because the alternate color gives us pause to actually think about the fact that we are eating (ie avoiding Mindless Eating), or to think about how much we have eaten, or how much we should be eating.  It is also possible that the color gives us a subconscious cue to portion control.

Perhaps in the future, we will see a new wave of colored snack products on the shelves in response to this study.   In the meantime, think about what your favorite snacks are, and how you could adapt them to take advantage of these findings.  I'd be thrilled to hear your ideas!

Dr Sue Pedersen www.drsue.ca © 2012

drsuetalks@gmail.com 

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Liposuction Increases Bad Fat

While liposuction is a commonly performed cosmetic procedure, the long term health effects are not well understood. A recent study reveals that not only is there regain of fat after liposuction, but that fat regain is in the form of ‘bad fat’ – the fat that increases the risk of diabetes and heart disease.

The study evaluated 36 healthy, normal weight women, who underwent abdominal (tummy) liposuction at the University of Sao Paolo, Brazil.  Two months after surgery, participants were randomly allocated to two groups: one group was put into a 4 month exercise program, and the other group was not put onto an exercise program.

At 6 months after liposuction, while fat did not reaccumulate in the area of liposuction, the group that was not in the exercise program had a 10% increase in visceral fat – this is the fat that surrounds our organs, which, in excess, is the ‘bad fat’ that secretes hormones and inflammatory chemicals that increase our risk of getting diabetes and heart disease.  The ‘bad fat’ did not increase in the exercise group, suggesting that the physical activity was sufficient to keep the bad fat at bay.

So, what this study teaches us is that although the lipo-sucked areas do not reaccumulate fat, the body’s compensation mechanisms do kick in to reaccumulate fat in more dangerous places around the organs, thereby increasing the risk of health complications of excess fat.  While exercise kept the bad fat away in this study, it would be very interesting to see what happened to these women six months or a year after the study was complete – if they stopped exercising, did they regain bad fat too?  Yet another research study that needs to be done.  

Dr Sue Pedersen www.drsue.ca © 2012

drsuetalks@gmail.com 

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Breast Feeding and Obesity Risk Later in Childhood

There is a long list of established benefits of breast feeding, including benefits to baby's immune defenses, gastrointestinal function, nutrition, and psychological well being.  It is controversial as to whether breast feeding decreases the risk of obesity later in life, but the evidence is mounting, with another new study lending support to this claim.

The study by Cathal McCrory and colleagues examined data from nearly 8,000 Irish children and their families, to see if breast feeding vs formula feeding had an impact on the risk of obesity later in childhood.  They found that kids who had been breast feed for 3 to 6 months were 38% less likely to be obese at 9 years of age, compared with kids who were exclusively formula fed.  Those who were breast fed for 6 months or more had half the risk of obesity at age 9, compared with formula fed kids.

While the mechanism responsible for these findings is still up for debate, the study lends further credence to the mantra we already know: Breast is Best!

Dr Sue Pedersen www.drsue.ca © 2012

drsuetalks@gmail.com 

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Healthy Obesity - Is There Such A Thing?

In this era where obesity is so prevalent, the question has arisen as to whether everyone with obesity is at risk of developing complications of their excess weight, such as heart disease.  It turns out that all obesity is not equal, and that Healthy Obesity is a very real phenomenon.

A recent study that adds to our growing knowledge on this topic examined data from over 22,000 people in the United Kingdom, and compared the risk of developing cardiovascular disease, or death, in people who were obese vs not obese, according to whether they had other metabolic risk factors for cardiovascular disease or not (including high blood pressure, low levels of good cholesterol, diabetes, waist circumference, and a blood marker of inflammation called CRP).

Over an average of 7 years, the obese people who were metabolically healthy (with 0 or 1 of the above risk factors) were not at increased risk of cardiovascular disease, compared with metabolically healthy people who were not obese.  Amongst people who were metabolically unhealthy (with 2 or more of the above risk factors), body weight didn't make a difference in risk - it was the metabolic factors that mattered, not the body weight.   Amongst people with obesity, those who were metabolically unhealthy were at 72% increased risk of death compared to those who were metabolically healthy.

The bottom line here is that it is not body weight that is the primary determinant of health, but rather, it is the risk factors for disease that may or may not be present (or develop) in the person who carries excess body weight that are the key.  In this study, one quarter of the people who were obese were metabolically healthy, and were therefore not at increased risk.

Once again, we learn that it is not about 'curing' obesity.  Rather, it is about each individual achieving their Best Weight - a realistic weight goal (which is different for everyone) that optimizes metabolic health and overall wellbeing.

Dr Sue Pedersen www.drsue.ca © 2012

drsuetalks@gmail.com 

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Medications vs Bariatric Surgery for Treatment of Type 2 Diabetes

It has become clear that bariatric (obesity) surgery can result in substantial improvement, or even remission, of type 2 diabetes for some people.   Two new articles from the New England Journal of Medicine now add to our knowledge on this topic.

(For the non-scientists in the audience, feel free to skip down to 'So what does this mean?' below.)

One of these studies, by Mingrone and colleagues, looked at 60 patients randomized to receive either gastric bypass surgery, biliopancreatic diversion surgery (BPD), versus their usual diabetes care with medications, and examined how many people would be in remission from their diabetes 2 years later.  They found that 75% of the patients who had gastric bypass and 95% of the patients who had BPD were in remission, whereas none of the control group was in remission.  Interestingly, none of age, gender, baseline body mass index, nor duration of diabetes were predictive of remission.

The other study, by Schauer and colleagues, randomized 150 patients to receiving either gastric bypass surgery, sleeve gastrectomy, versus usual medical care of type 2 diabetes, with the goal being to see how many patients from each group could achieve very tight control of their diabetes (defined by A1C of 6% or less) at one year.  They found that more patients who had surgery achieved this goal (42% of gastric bypass patients and 37% in sleeve gastrectomy patients), compared with 12% of patients receiving medications alone.  At one year, the mean A1C in the medication group was 7.5%, compared to 6.4% in the gastric bypass group and 6.6% in the sleeve gastrectomy group.

While each of these studies could be discussed with chapters of detail, for purposes of brevity I'll highlight just a couple of important caveats.  While a strength of these studies is that they are randomized clinical trials (very hard to do in the area of bariatrics), both studies are small.  In the Mingrone study, BPD was used as a surgical technique, which is a fairly drastic surgery (it bypasses more of the bowel than gastric bypass), and is currently only experimental.  The longer term follow up of these patients is important, as other studies now suggest that at 5 years after bariatric surgery, about half of the diabetes cases that initially went into remission come back (though the diabetes-free years are undoubtedly still of substantial health benefit).   In the Schauer study, one could argue that the diabetes control goal (A1C 6% or less) was too tight and not appropriate for routine clinical care, given that we no longer strive for this tight control in most cases of type 2 diabetes because of the potential risk of harm (see the ACCORD trial).  What is interesting to me, however, is that the overall control was better in the surgical groups compared to the control group.

So what does this mean?  These studies show us that bariatric (obesity) surgery can put type 2 diabetes into remission, and can improve control of diabetes in those who don't go into remission.  However, it must be noted that remission does NOT mean cure - each patient must be followed on a lifelong basis and monitored for possible recurrence of diabetes down the road.  These surgeries have significant risk associated with them, and the balance of benefit versus risk has to be considered on a patient-by-patient basis.  The improvement in diabetes does not appear to depend on how much the person weighs before surgery, implying that the current body mass index (BMI) critieria for selecting patients for surgery may not be the right way to determine who would benefit the most. (More research needs to be done to figure out what does predict best success with bariatric surgery.)

Overall, (and as noted in the accompanying editorial), studies such as these suggest that bariatric surgery should perhaps not be a 'last resort' in the treatment of patients with obesity and type 2 diabetes.

Dr Sue Pedersen www.drsue.ca © 2012 drsuetalks@gmail.com

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The Science Behind Comfort Foods and the Stomach Brain Connection

Have you ever wondered why you might feel the urge to reach for a chocolate bar or a bowl of ice cream after receiving some bad news?   Or why that baked mac n' cheese really does fit the bill of a 'comfort food'?  The effect on mood that we often feel after eating these foods is not a figment of our imaginations - it is a physiologic reality that high fat foods affect our emotions, and it turns out that it goes farther than the enjoyable taste, smell, or texture of these foods.  In fact, a recent study provides some interesting evidence to suggest that a direct message from the stomach to the brain in response to a fatty meal may play a role in this fascinating phenomenon.

A rather ingenious study (in my opinion) published by Van Oudenhove and colleagues in the Journal of Clinical Investigation infused a solution of either fats or salt water directly into the stomachs of 12 healthy, non obese volunteers (thereby bypassing any satisfaction or pleasure derived from the taste, smell, or texture sensations of a fatty meal).  Along with these infusions, they induced feelings of either sadness or neutral emotion, using pictures and music, and asked them to rate their mood.

The researchers found that hunger scores were higher during the sad emotion than during the neutral emotion (supporting that a down mood promotes hunger).  While they did not find that the fat infusion decreased hunger compared to the salt water infusion, they did find that the difference in hunger ratings between the sad and neutral conditions was less during the fat infusions than it was during the salt water infusions, suggesting that the fat infusion has an effect to take the edge off of, or lessen the blow of, the effect of sadness on hunger.

They also found that while there was no difference in sadness ratings in the fat infusion versus the salt water infusion, the difference in sadness ratings between the sad and neutral conditions was less during the fat infusions than during the salt water infusion.  Again, this suggests that fat has an effect to moderate sadness such that it feels like less of a roller coaster ride.

The researchers also looked at parts of the brain involved in sadness using functional MRI, and found that the fat infusions had an attenuating (lessening) effect on the activity of some of these areas of the brain in response to induction of sadness, compared to the salt water infusions.

Putting these findings together, it suggests that there may be a direct signal from the stomach to the brain  after taking in a fatty meal, which may lessen the feeling of hunger that sadness induces, and may lessen the swing between neutral mood and sadness.  What this message is, exactly, is unknown, but it is likely that gut hormones are involved in this fascinating response.

These findings beg the question:  Is the effect of a fatty meal on mood, or mood swings, or perception of sadness, different in people who struggle with their weight, compared to normal weight individuals?  Do people with obesity have less mood modulation after consuming a similar amount of fatty food than nonobese individuals, thereby resulting in the need to eat a larger fatty meal in order to feel better or more emotionally stable?  Or, do individuals with obesity have more mood improvement or stability with eating a fatty meal, thereby providing a greater emotional reward and causing that individual to be more inclined to seek out high fat meals in the future (eg in the case of food addiction)?


Very, very interesting, and most deserving of further research.



Dr Sue Pedersen www.drsue.ca © 2012 drsuetalks@gmail.com

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Is Global Warming Contributing to Obesity?

In parallel with the rising obesity rates around the world over the last decades, so too have we seen an environmental trend of global warming.  I never stopped to consider that the two might be related - until now.

A thought provoking paper just published by my Danish colleagues suggests that there may be a link between increasing atmospheric carbon dioxide levels (as observed with global warming) and obesity.  Breathing in air containing higher carbon dioxide (CO2) level causes the pH of the blood to decrease ever so slightly.   The brain is exquisitely sensitive to these small changes, and the activity of neural cells that are involved in appetite regulation are affected.  In addition, these decreases in pH may affect neurons that regulate wakefulness, resulting in less sleep, which is a known risk factor for obesity.

Therefore, they hypothesize that these small pH changes in our blood seen with higher CO2 concentrations in the air could lead to an increase in appetite as well as energy storage, and could therefore be one of the many contributors to the high rates of obesity that we currently see.

My colleagues went on to test this theory in a small study of six participants, and found that study participants consumed 6.1% more calories when exposed to higher CO2 concentrations in the air, compared to ambient air.  It is noted that this difference was not significant in the study, but a study of a larger size is now needed to see if there is a real difference here.

The obesity endemic, therefore, may be one more important item to add to the list of reasons to put a stop to global warming.

Dr Sue Pedersen www.drsue.ca © 2012

drsuetalks@gmail.com 

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Does The Composition of Your Diet Affect POUNDS LOST?

The research world has long been trying to figure out whether the protein, carbohydrate, and fat content of a diet matters, or whether it is 'simply' all about the number of calories being taken in, that determines the end effect on weight.  While a large clinical trial suggested that the composition of the diet doesn't matter, there may be certain elements of this trial that make it difficult to draw these conclusions.

In the POUNDS LOST trial, originally published in 2009 in the New England Journal of Medicine, over 800 overweight adults were randomly assigned to diets with different proportions of fat, carbs, and protein.  At the two year follow up, weight lost was similar in all groups, regardless of the diet composition, leading the authors to conclude that the composition of the diet doesn't matter, and that it's all about the calories.

In a follow up to the POUNDS LOST trial, the authors recently published further data suggesting that there was not only no difference in weight between the various diet groups, but no difference in changes in body composition, abdominal fat, or liver fat lost between the groups either.

In an accompanying editorial in the American Journal of Clinical Nutrition, my colleague Arne Astrup and I comment that further analysis of the POUNDS LOST data show that, based on urine excretion of nitrogen, which is a marker of dietary protein intake, there was actually no difference in protein intake between the low and high protein diet groups.  In other words, despite being assigned diets with different protein content, the participants ended up eating the same amount of protein after all.   As such, it is not actually possible to assess the effect of protein content on weight loss success based on this study.

The heart of the problem is that it is very difficult for study participants to adhere to a hard and fast dietary regimen for the duration of a study.  Although people in this study were asked to eat different amounts of protein, they ended up eating much the same.   Much better is to design dietary trials which point participants towards consumption of certain types of foods, without a fixed caloric intake or diet composition assigned.  That way, we can study how different types of foods affect weight via their natural effects on hunger and satiety.  This is a much more practical way to address the obesity epidemic from a research perspective, as it more accurately represents eating patterns in real life!

Dr Sue Pedersen www.drsue.ca © 2012

drsuetalks@gmail.com 

Follow me on Twitter for daily tips! @drsuepedersen  

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Photos in Lunch Trays Increase Veggie Consumption in Kids

While the focus of healthy eating tableware tends to be on limiting portions of carbs and proteins, a study group out of Minnesota took a different slant with a group of kids by putting photos of vegetables in their lunch trays - and it worked!

The study, recently published in the Journal of the American Medical Association, looked at the consumption of carrots and green beans at a school cafeteria, comparing eating patterns on a day with pictures of carrots and green beans placed in the bottom of the tray, to a day when there were no pictures placed in the tray.   Kids helped themselves on both days to these vegetables as they wished, and were not aware that their selection or eating patterns were being recorded.

They found that the number of kids who selected green beans more than doubled (from 6.3% to 14.8%), and the number who selected carrots more than tripled (from 11.6% to 36.8%).  However, the number of kids choosing these vegetables overall was still low; further, the amount consumed was low, and did not meet government recommendations.

What this study teaches us is that the power of suggestion can have an impact on helping kids make healthier choices, with minimal additional cost above other much more expensive interventions such as structured classroom teaching.  While the classroom teaching is a crucial part of teaching our kids to eat healthy, let's not forget that a picture speaks a thousand words!

Dr Sue Pedersen www.drsue.ca © 2012

drsuetalks@gmail.com 

Follow me on Twitter for daily tips! @drsuepedersen 

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How You Taste Fat May Be Genetically Determined

As the human genome is being explored in more detail, the genetic contribution to obesity is becoming increasingly recognized.  While we know of at least 45 genes that contribute to obesity, little is understood about how they work.  A new study has discovered a gene that affects how we sense and taste fat in our mouths, and postulates that this gene may be one more mechanism that contributes to the development of obesity in people who are genetically prone.

The study, conducted by MY Pepino and colleagues at Washington University, looked at 21 people with obesity and different variants of a gene called the CD36 gene.  They found that people who had two copies of a certain variant of the CD36 gene had an 8 fold lower threshold for sensation of fat than people who had no copies of this gene variant.  In other words, people with two copies of the gene variant were far more sensitive to the taste of fat than people without this gene variant.

Exactly how these genetic differences affect food intake is not known.  It may be, for example, that people who are less sensitive to the taste of fat need to eat more fat to feel satisfied.   Further study is needed to understand how the difference in sensitivity to the taste of fat may affect food intake and body weight.

What is increasingly clear is that genetics have a powerful role in the risk of obesity, in the context of the toxic enviroment in which we live.

Note: you can read more about the genetics of obesity here.

Dr Sue Pedersen www.drsue.ca © 2012

drsuetalks@gmail.com 

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