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What We Don't Know about Absorption of Medication after Gastric Bypass Surgery

>> Friday, April 29, 2011

Although there are now over 160,000 gastric bypass surgeries being performed on an annual basis world wide, there is still much that we are still learning about postoperative management of concomitant medical conditions.  One area in which we know very little is in regards to the effect of gastric bypass surgery on the absorption of medications taken orally.

Because gastric bypass surgery causes food to bypass about the first 1.5m of small intestine, the absorption of some medications may be significantly impaired as well.  One medication that is particularly relevant in the gastric bypass population is metformin, as it is the first line of treatment to treat type 2 diabetes, and is also used to prevent diabetes in patients who have prediabetic blood sugars.  Although gastric bypass surgery results in remission of type 2 diabetics in about 80% of people initially, about half of these cases of diabetes recur by 5 years postoperatively, so metformin use may be considered at some point in a signficant number of these patients.

At the Second Canadian National Obesity Summit in Montreal today, Dr Raj Padwal of the University of Alberta presented the results of a recent study that were published in the journal Diabetes Care, looking at the absorption and bioavailability of metformin in patients who have had gastric bypass surgery.

In this study, 16 patients who had gastric bypass surgery were administered a single dose of 1,000 mg of metformin, and their absorption of metformin was compared to 16 gender and BMI matched control subjects who had not had gastric bypass surgery.  Surprisingly, they found that metformin absorption was actually increased in patients who had had gastric bypass surgery - exactly the opposite of what was expected.

Although this was a small study and tested only a single dose of metformin, it raises some interesting questions.  Does the absorption of medications after gastric bypass vary depending on the normal absorption rate of a medication?  Does the surgery have some effect to alter transporters in the lining of the gut to accelerate absorption?

Other medications which are very relevant in this population include birth control pills (we currently recommend against using them to prevent pregnancy after gastric bypass because we don't know if their absorption is altered) and antidepressive agents (a slightly increased risk of suicide is seen after gastric bypass surgery - is this due to changes in the patient's environment, a difficulty in breaking the emotional bond with food - or, as Dr Padwal questioned in his commentary today, could impaired absorption of antidepressive medications play a role?).

Further studies clearly need to be done to improve our understanding of medication absorption after gastric bypass surgery.

Dr. Sue © 2011

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115 Calorie Chocolate Espresso Brownies as a Holiday Treat!

>> Saturday, April 23, 2011

It's holiday weekend!  Families and friends are gathering to celebrate the occasion, often with heaping trays of food, snacks, and desserts in tow.  The sweets enjoyed at the end of the meal are a significant contributor to the total caloric intake of a meal, and can easily provide as many or more calories as the meal itself.  

As such, I would like to share with you one of my very favorite recipes.   These chocolate espresso brownies are absolutely delicious - they are moist and satisfying, and you'd never guess that they contain only 115 calories per square!  The secret that makes this recipe low calorie yet very flavorful is that cocoa powder is used instead of chocolate.   And no, the brownies are not microscopic - they are appropriately portion controlled at 1/16 of an 8x8" pan.  

For diabetics, please note that the carbohydrate content is about 17 grams per square.  This is not a lot of carbohydrate, but they are simple carbs (sugar and flour), making this a high glycemic index food (a deviation from the recommendations of choosing complex carbohydrates with a low glycemic index).  Therefore, these squares may cause blood sugars to rise a little more than a complex carb food would.  Having said that, one square as a special Easter dessert would be a much better choice than many other desserts, which can easily contain several fold higher carbohydrate and calories.


  • 2/3 cup unsweetened cocoa powder
  • 1/3 cup all purpose flour (or try whole wheat flour for a more complex carb)
  • 1/2 tsp baking powder
  • 1/3 cup canola oil
  • 1/2 cup packed dark brown sugar
  • 1/2 cup granulated sugar
  • 4 large egg whites
  • 1 tbsp instant espresso powder (I like to use a Starbucks Via!)
  • 1 tbsp hot water
  • 1 tbsp coffee flavored liquor
  • 1 tsp vanilla extract

Heat oven to 350F.  

Whisk together cocoa, flour and baking powder. 
In a separate bowl, stir together canola oil and sugars. 
In a small bowl, whisk the egg whites until they are foamy. 

In a small cup, dissolve the espresso powder in 1 tbsp hot water.  Stir coffee, coffee liquer and vanilla extract into the canola/sugar mixture, along with the egg whites.  Gradually stir this into the cocoa mixture, until well blended.

Pour the batter into an 8x8 inch baking pan lined with foil and coated with cooking spray. Bake 25 minutes, or until a skewer inserted into centre comes out clean.   Cool completely before cutting into squares.

Makes 16 brownies.

Per brownie:
115 cal, 2g protein, 17g CHO, 5g fat, 1g fiber.

Note that these brownies don't have any icing - they don't need it, as they are so rich on their own.  For decoration, consider adding one dark chocolate chip to the top of each one while they are still warm (for an additional 2.5 calories!).

It can be a challenge to maintain a healthy dietary pattern on weekends like this!  Remember to practice portion control at all aspects of the meal as well, and to make healthy food choices wherever possible!

Dr. Sue © 2011

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FDA Gives Thumbs Up to Broader Lap Banding Indications While Research Gives Thumbs Down to Long Term Outcomes

>> Saturday, April 16, 2011

For some individuals, despite intensive and longstanding attempts at shedding pounds and exhausting every possible lifestyle intervention or medical therapy, weight loss remains elusive.  In some cases, weight loss surgery (called 'bariatric' surgery) may be the most appropriate option.  Bariatric surgery has typically been reserved for the most extreme cases, but recently, the American FDA has lowered the Body Mass Index (BMI) requirements for eligibility to undergo laparascopic adjustable gastric banding ('lap band') surgery.

As blogged previously, bariatric surgery has traditionally been reserved for the most serious cases of obesity, defined as a Body Mass Index of 40 or greater, or, a BMI of ≥ 35 with one or more serious complication of obesity, such as diabetes, obstructive sleep apnea, or high blood pressure (you can calculate your own BMI in the right hand column here).  However, because of the impressive success that bariatric surgery can have to result in weight loss and reduce complications of obesity, the FDA has lowered the required BMI for a patient with a serious complication of obesity to 30 for the lap band procedure.

However, as blogged previously, recent study suggests that lap banding may actually have a poor long term outcome.   It is interesting that the FDA seems to be embracing the most extreme of obesity treatments by expanding indications for bariatric surgery, in a form that may be associated with poor long term outcomes, while simultaneously (and in some experts' opinions, perhaps stringently) rejecting a lineup of three potential new weight loss medications in the last year.

For Canadians, the BMI criteria for bariatric surgery remain unchanged.  If we were to follow our US counterparts with a broadening of the BMI criteria, it would make little practical difference in any case, as the average wait time for bariatric surgery across Canada is over half a decade.  In addition, in light of recent study suggesting that lap banding may have a poor long term outcome, other types of bariatric surgery (such as gastric bypass) may be more appropriate to consider, though these other forms of surgery have a significant risk of complications as well, and long term outcomes of these procedures are not yet well known.

Dr. Sue © 2011

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Dangers of the Very Low Calorie Diet

>> Saturday, April 9, 2011

For people struggling with overweight and obesity, there are an overwhelming number and variety of diet strategies that are available in the commercial marketplace.  With the wide diversity of options available, it can be confusing to sort through them, and to know if some are better than others.  One thing is certain: any diet plan that includes a very low calorie diet can be downright dangerous.

A 'Very Low Calorie Diet' is defined as any diet providing less than 800 calories per day.  These diets  aim to supply very little energy, while trying to supply essential nutrients.  They often seem very attractive because of the rapid weight loss that often occurs on these diets.  However, there are several safety concerns with these Very Low Calorie Diets, including the following: 

1.  Potentially fatal heart rhythm disturbances may occur.  These diets cause a rapid shift in water balance, especially in the early phases, which can lead to dangerous alterations in the balance of electrolytes that are important to normal heart function and rhythm (especially potassium).   Over the longer term on these diets, even after the initial fluid shifts settle down, these electrolyte imbalances and heart rhythm disturbances can still occur. 

2.  Very low calorie diets are likely to be nutritionally insufficient.  Because so little food is being taken in, it is very difficult to obtain sufficient amounts of the important vitamins and minerals that are needed for the daily function of our body and cells.

3.  Due to the rapid weight loss that is seen on these diets, there is an increased risk of gallstone formation.  (Any intervention that causes rapid weight loss can cause gallstone formation - weight loss surgery is another example of this.)

In addition to the safety concerns above, the very low calorie diet is highly unlikely to result in successful and sustained weight loss over the long run.  Though they can result in a substantial and rapid weight loss, they teach nothing about how to modify dietary habits in the long term.  Therefore, when an individual stops one of these diets (and they do stop at some point, as they are simply not sustainable over the long term), a rapid weight gain most often ensues, as that person returns to their old habits and way of life. 

In addition, a number of studies have shown that a diet providing 500-600 calories per day does not produce a greater weight loss compared to diets comprising 800 calories per day.  It has been suggested that the body may go in a 'starvation mode' on the very low calorie diets, downregulating its metabolic rate and calorie burn, as an evolutionary tactic designed to survive times of starvation.  In other words, these diets may negatively affect your baseline metabolism while on the diet, such that your calorie burn is lower, thereby leaving you with no greater weight loss benefit, but putting you at all of the risks that come with these low energy diets.

In order to successfully lose weight, the calories in must be less than calories out - no doubt.  However, a permanent lifestyle change that results in a more moderate rate of weight loss is much safer, much more enjoyable, and sustainable!  We generally recommend a weight loss of 1 pound per week, which can be achieved by a typical woman on about 1,200 calories per day, or by a man on about 1,700 calories per day, though this number can vary substantially from person to person.  You can calculate your own caloric requirement for weight maintenance or weight loss using the BMR calculator here.

Dr Sue Pedersen © 2011

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Iced Pumpkin Fiber Muffins!

>> Sunday, April 3, 2011

Pumpkin is a fantastic ingredient to consider for use in your baking.  It weighs in as a low calorie food at only 30 calories per cup, and it lends a fantastic moisture to your baking that makes it easy to bake without oil or butter.  I have scoured the internet to find a good, healthy, pumpkin muffin recipe, and here it is:  The Hungry Girl does it again!

These muffins are delightful!  They are made with one of my favorite sources of fiber, that being Fiber One Cereal (All Bran is my other favorite source).  They taste great with or without icing.  Should you choose the 'with icing' alternative, consider sprinkling a little cinnamon (and maybe just a little extra Splenda) on top.

1 cup Fiber One Original bran cereal
1 1/2 cups whole-wheat flour
1/2 cup Splenda No Calorie Sweetener (granulated)
1/4 cup brown sugar (not packed)
1 tbsp. baking powder
2 tsp. cinnamon
1/2 tsp. pumpkin pie spice
1/4 tsp. salt
One 15-oz. can pure pumpkin
1 cup club soda
1/2 cup fat-free liquid egg substitute (like Egg Beaters Original)
1/4 cup sugar-free pancake syrup
1 tsp. vanilla extract
1/4 cup raisins, chopped

1/4 cup Cool Whip Free, thawed
3 tbsp. fat-free cream cheese, room temperature
1 tbsp. Splenda No Calorie Sweetener (granulated) 

Preheat oven to 350 degrees. Line 10 cups of a 12-cup muffin pan with baking cups and/or spray with nonstick spray. Set aside.

Using a blender or food processor, grind cereal to a breadcrumb-like consistency. Transfer crumbs to a large bowl.
 Add flour, Splenda, brown sugar, baking powder, cinnamon, pumpkin pie spice, and salt. Mix well and set aside.

In another bowl, combine pumpkin, soda, egg substitute, syrup, and vanilla extract. Mix thoroughly. Add mixture to the large bowl and stir until blended to form the batter.

Slowly sprinkle and stir chopped raisins into the batter. Evenly distribute batter among the 10 prepared cups of your muffin pan. (Batter may be piled high... This is OK!)

Bake in the oven until muffins are golden brown and a toothpick inserted into the center of one comes out mostly clean, about 30 minutes. Set aside to cool.

Meanwhile, combine all icing ingredients in a small microwave-safe bowl. Mix until smooth and blended. (Refrigerate icing if you don't plan to serve muffins right away.)

Remove cooled muffins from the pan. Just before serving, warm icing in the microwave for a few seconds and drizzle it onto the muffins (or simply spread it on evenly). Enjoy!

Serving Size: 1 iced muffin

Calories: 150
Carbs: 30g
Fiber: 4g

Dr Sue Pedersen © 2011

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I am excited that you have arrived at my site, and I hope you are too - consider this the first step towards a Healthier New You!! As a medical doctor, Endocrinologist, and obesity specialist, I am absolutely passionate about helping people with weight management. Though there is certainly no magic cure for obesity, there IS a successful treatment plan out there for you - it is all about understanding the elements that contribute to your personal weight struggle, and then finding the treatment plan that suits your needs and your lifestyle. The way to finding your personal solution is to learn as much as you can about obesity: how our toxic environment has shaped us into an overweight society; the diversity of contributors to obesity; and what the treatment options out there are really all about. Knowledge Is Power!!

Are you ready to change your life? Let's begin our journey together, towards a healthier, happier you!!

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