Hunger After Gastric Bypass

I just attended another fabulous conference, The 24th Annual International Conference on Practical Approaches to the Treatment of Obesity. I learned a lot about new surgical techniques and heard an intriguing new way to understand the honeymoon period after gastric bypass. I'll write about that when I have an article to discuss.

Today we turn to the experience of hunger. During the first 12-24 months after gastric bypass, most patients report a drastic change in their experiences of hunger and taste. And they are usually totally surprised and delighted. Someone suddenly prefers yogurt to chocolate. Another can be satisfied with one bite of a piece of cheesecake and literally throw the rest away. Someone else enjoys vegetables for the first time in her life.

Researchers at the Interdisciplinary Obesity Center in Rorschach, Switzerland (I swear, that is not a joke, here's the link: http://www.kssg.ch) wanted to investigate hedonic hunger before and after gastric bypass and in non-obese controls. By hedonic hunger we mean the drive to eat palatable foods in the absence of energy need. (Think hedonism, the desire for pleasure.)

So, hedonic hunger might include emotional eating, cravings for certain foods even after eating a meal, and that gnawing need for something even when we're not hungry. Before you start cursing human biology for this drive to eat in the absence of the need for calories, let's see if this drive might be adaptive. By adaptive I mean, did it serve an evolutionary purpose? Did a behavior or a physiological response increase an individual's or a species' chance of survival?

I think so. Let's consider a college dorm. I used to use this example with my intro psych students all the time in a discussion of motivation. Let's say you just ate dinner and are comfortably full, about to hit the books for the night. A friend sticks his head in your room and asks if you want in on a pizza. "No, thanks," you say, "I just ate." And you dutifully open your books.

Half an hour later the pizza arrives and the aromas of bubbly cheese, meat and fresh dough permeate the corridor. You are still not hungry but that smell is absolutely unavoidable! Before you know it, you are eating a piece of pizza. And you do feel some hunger and it does taste great. Your appetite changed in response to the environment.

Now replay this vignette about 100,000 years ago when one's appetite needed to adjust itself in response to food in the environment. Let's say you are not especially hungry, but the smell of fresh-killed meat wafts its way to you. It was adaptive for you to generate some hunger and eat because you never knew where your next meal was coming from.

Of course, in 2010, an excess of hedonic hunger can contribute to obesity. Food is so readily available that we do not need to adjust our hunger in response to the environment. But try retraining the primitive parts of your brain to eat only when they are hungry and let me know how that works out!

So, the study. The researchers used an instrument called the Power of Food Scale (PFS) that measures one's mental experience of and preoccupation with food overall and in 3 contexts: when food is available, when food is present, and when food is tasted. Here's a taste (couldn't resist) of some of the items:

      I find myself thinking about food even when I'm not physically hungry.

      When I know a delicious food is available, I can't help myself 

      from thinking about having some.

      When I'm in a situation where delicious foods are present 

      but I have to wait to eat them, it is very difficult for me to wait.

      When I taste a favorite food, I feel intense pleasure.

They had 3 groups of participants: patients preparing for bariatric surgery, patients who had had gastric bypass at least 1 year ago, and non-obese controls. The results are in line with the researchers' hypotheses that hedonic hunger decreases after gastric bypass:

For the total PFS score, the Food Available subscore, and the Food Present subscore, post-bypass patients did not differ from the non-obese controls, and the pre-bypass patients reported significantly higher ratings. Further, the post-bypass patients reported significantly lower on the Food Tasted subscore than both other groups.

So, how does this contribute to our understanding of the gastric bypass honeymoon period? These results show a difference in the post-bypass patients' mental experience of and preoccupation with food, bringing them in line with non-obese controls. The quantitative results of the PFS support the qualitative reports of patients in that first year after surgery.

Two points come to mind, one regarding future research and one regarding an overarching theory. One drawback of this study is that it is cross-sectional. This simply means that the pre-surgery group and the post-surgery group were different people. A more powerful design is a longitudinal approach, in which the same individuals are evaluated before and after surgery. An even more interesting study would be a longer longitudinal approach, to track the mental power of food through the first few years after surgery and gain greater insight into the gastric bypass honeymoon period.

Regarding theory, I can't help but think of one of the diagnostic criteria for substance dependence:

      a great deal of time is spent in activities necessary to obtain

      the substance, use the substance, or recover from its effects.

The mental effort dedicated to planning, obtaining, consuming, and enjoying the effects of an addictive drug can become ritualized, with favorite settings, companions, utensils, and other environmental factors necessary for the full experience of the substance. Might the preoccupation with obtaining food, preparing food, sometimes sneaking food, consuming food and recovering from its effects be considered in the same light? I'm not saying I think all food is addictive (see previous posts) but there does seem to be a similarity in the mental experience of those who struggle with both food and addictive drugs.




Schultes, B., Ernst, B., Wilms, B., Thurnheer, M., & Hallschmid, M. (2010). Hedonic hunger is increased in severely obese patients and is reduced after gastric bypass surgery American Journal of Clinical Nutrition DOI: 10.3945/ajcn.2009.29007


Lowe MR, Butryn ML, Didie ER, Annunziato RA, Thomas JG, Crerand CE, Ochner CN, Coletta MC, Bellace D, Wallaert M, & Halford J (2009). The Power of Food Scale. A new measure of the psychological influence of the food environment. Appetite, 53 (1), 114-8 PMID: 19500623

Support Eating Disorders Research

My dear friend, Dr. Ann Goebel-Fabbri of the Joslin Diabetes Center, is running a race this weekend and raising funds to support her research on eating disorders in people with Type 1 diabetes.  Here's her email and a link to contribute to this important work.


Hi Family and Friends,

Well, it’s that time of year again. This Sunday, I am running the Litchfield Hills Road Race and raising funds and awareness for eating disorders and type 1 diabetes. First, I want to thank all of you who supported the cause (and my run) last year. You have been most generous, and I appreciate any support for this important cause.

Attached is my weblink below:
https://events.joslin.org/teamjoslin/pfp/?ID=GA0004

The best thing you could do (apart from supporting the fund yourself) is to forward this onward to as many people as you can. If “viral marketing” worked for President Obama, then it can work for me!

Thanks to all of you for your generous support. Last year, I ran 4 minutes over the time I had at age 21. This year, at 41, I hope to tie with my 21 year old self, or kick that self into the dust!!

Much love and thanks,
Ann
 

Welcome, Part 2

Welcome to GourMind!

On this, the day of my "official" launch, I feel I have enough momentum to trust I will keep writing and thus warrant your continued attention. In this post, I want to acknowledge two people who make this blog possible, give you some tips for enjoying blogs (in the event that you are new to them), and recommend some of my favorite blogs.

First tip: this is the newest entry in the blog. To read the rest in chronological order, scroll down or use the directory on the right to get to the first entry.

Soapbox moment: I love the idea of introducing high school and beginning college students to science through blogs. Many bloggers excel at translating complex research into easily understandable prose. So please bring your youngsters to some of the science sites named below and encourage them to find others that are interesting to them.

Acknowledgments . . .

Steven Roach is my wonderful research assistant. He is a Harvard undergrad who has been a tremendous help in navigating the research literature. Happy summer vacation, Steven, and thanks for all your hard work.

Lisa Schreider is my personal assistant (and lots of other people's too) who makes it possible for me to have the time to work on special projects like this blog. Lisa is a tremendous resource and I feel fortunate to have her in my life. Check out her business at:

http://www.lisashandsoftimeconcierge.com/

Now, for those of you who are new to the world of blogs . . . let me introduce you to a few helpful services:

(1) Google Reader is a central site that lets you track new entries on your favorite blogs:

http://www.google.com/reader

You can add the addresses of all the blogs you are following on Google Reader. Then you simply check that page to see if there are new entries, called posts, on your set of blogs. There are other such sites as well.

(2) Research Blogging is a directory of blogs that describe and critique peer-reviewed scientific research. GourMind is a member. You can search Research Blogging for blogs about topics you are interested in. For example, if you search for GHRELIN, some of my posts will pop up. It also allows direct links to the research articles published online. (You or your institution still have to have a subscription most of the time.) When you see this symbol in a blog:








it means that it is indexed in Research Blogging. Here's the link:

http://researchblogging.org/

(3) Another outstanding collection of blogs is Science Blogs, an elite group of writers who have been invited to participate. You'll also see some of these writers in The New Yorker, The New York Times, The Wall Street Journal, Nature, and Wired. Find lots of fascinating science here:

http://scienceblogs.com/

Finally, some of my favorite blogs:

Neurotopia                 http://scienceblogs.com/neurotopia/

The Frontal Cortex      http://scienceblogs.com/cortex/

We're Only Human      http://onlyhumanaps.blogspot.com/

Obesity Panacea         http://scienceblogs.com/obesitypanacea/

Dan Ariely                  http://danariely.com/
(Author of the great Predictably Irrational)

So . . . enjoy GourMind and any other sites that enrich your mind and your life. Write comments, ask questions, and connect with other readers and writers.  

Thanks for your attention and your participation!

I met Ana Sortun!!

Last week I attended the annual conference of the Association for Psychological Science here in Boston. I learned a lot and may be blogging in future posts about some of the presentations I saw there.

So, how did I meet Ana Sortun of the famous Oleana restaurant in Cambridge? Our current president Linda Bartoshuk has researched taste over the course of her distinguished career. Linda invited Chef Sortun among others to her Presidential Symposium, titled "Spicing Up Psychological Science," presented to a packed Grand Ballroom at the Sheraton Boston.

Chef Sortun and Mimi Sheraton, former New York Times food critic, talked about spices and how strongly they relate to and evoke different cultures. Just think about how easily you can imagine and distinguish Thai food from southern Italian from Indian from Greek from Moroccan from . . . you get the idea. And what distinguishes these cuisines so clearly? Spice, of course. The "cool" flavors of dill and caraway take us to Scandinavia, while "hot" flavors suggest countries closer to the equator.

Chef Sortun has become known for combining spices in unexpected ways to create unique taste experiences. She created some appetizers for us that teased our taste buds to name the ingredients. And that's when I got to speak to her!

I'm so happy to report that she is a real sweetheart. (Don't you hate it when a famous person you admire turns out to be a jerk?) She seemed genuinely touched when I told her I had my 50th birthday party at Oleana. She even asked me if I cooked (!) and I told her about my passion for growing my own herbs.

Check out Chef Sortun's cookbook, appropriately titled Spice:

Also on the symposium panel was Marianne Gillette of the McCormick (no relation) spice company, who described McCormick's interest in research on medicinal and other effects of spices. The McCormick Science Institute's most impressive effort, in my opinion, is the creation and dissemination of standard samples of spices. This standardization supports the creation of a body of research that compares apples to apples, or, in this case, cinnamon to cinnamon! Here's the link:

http://www.mccormickscienceinstitute.com/

Add a little spice to your day . . . try something new . . . shake some cinnamon into your oatmeal or some dill onto your salmon.

Ghrelin after Gastric Banding vs. Sleeve Gastrectomy

In the last post, we discussed differences in ghrelin production after gastric bypass and sleeve gastrectomy. Today the studies we are going to consider describe the effects of gastric banding and sleeve gastrectomy on ghrelin and weight loss variables.

Langer et al. randomly assigned (love it!) 20 patients to either gastric banding or sleeve gastrectomy. The groups were well-matched on demographics and medical co-morbidities. The researchers measured plasma ghrelin levels at 4 time periods: preoperatively, 1 day after surgery, 1 month after surgery, and 6 months after surgery.

The results are consistent with what we saw in the last post, specifically, that the sleeve gastrectomy produced a significant, immediate and long-term decrease in plasma ghrelin levels. Most ghrelin is produced by the stomach in an area called the gastric fundus, and that part is simply removed by the sleeve gastrectomy. No more fundus, much less ghrelin.

And what about the banding? No change in ghrelin was seen after 1 day, but a significant increase occurred after 1 month and 6 months. Again, this is consistent with other studies we have examined . . . weight loss by dieting or other surgical techniques results in an increase in ghrelin. This is one way to understand yo-yo dieting and what used to be called the setpoint theory of body weight.

Himpens et al. compared other variables in 2 groups of randomly assigned (about to swoon!) patients, namely, weight loss, loss of feeling of hunger, loss of craving for sweets, new diagnoses of gastroesophageal reflux disease (GERD), and surgical complications.

Can you guess the results? Based on what we are learning about ghrelin, you might predict that the only significant differences would be in weight loss and loss of feeling of hunger . . . and you would be right. Specifically, sleeve gastrectomy patients had lost significantly more weight than the gastric banding patients after 1 year and 3 years, and they felt significantly less hunger at the same time points.

And the researchers like this as a working hypothesis . . . that decreased ghrelin production results in appetite suppression and weight loss. However, they also introduce another mechanical factor, the effect of gastric emptying on appetite, and they associate this change with the new anatomy of the stomach after sleeve gastrectomy. I need to read up on this, and maybe consult someone who knows more about this than I do, and get back to you.

The take-away message I want to send to everyone who struggles with their weight is this . . . there are serious and likely redundant biochemical mechanisms that are working to maintain your weight where it is. Sometimes, when it seems like your appetite has a mind of its own, maybe it does. Lighten up on yourself. Keep working to maintain health-promoting behaviors, but don't beat yourself up for being human.


Langer, F., Reza Hoda, M., Bohdjalian, A., Felberbauer, F., Zacherl, J., Wenzl, E., Schindler, K., Luger, A., Ludvik, B., & Prager, G. (2005). Sleeve Gastrectomy and Gastric Banding: Effects on Plasma Ghrelin Levels Obesity Surgery, 15 (7), 1024-1029 DOI: 10.1381/0960892054621125

Himpens, J., Dapri, G., & Cadière, G. (2006). A Prospective Randomized Study Between Laparoscopic Gastric Banding and Laparoscopic Isolated Sleeve Gastrectomy: Results after 1 and 3 Years Obesity Surgery, 16 (11), 1450-1456 DOI: 10.1381/096089206778869933

Comparing Ghrelin Levels Across 2 Bariatric Surgical Techniques

So, what have we learned so far? That ghrelin production is directly related to appetite in normals, but is unpredictable in post-bariatric surgery patients. And that studies of post-surgical patients in the U.S. and Sweden showed contradictory results. So let's throw in another variable - surgical procedure - as well as another location - Greece - and see what we can add to our narrative.

First, a little background from a non-surgeon. Gastric bypass is a procedure in which the stomach is reduced in size from that of a football to that of an egg or even a walnut. The reduction is accomplished by surgically stapling a line through part of the stomach so that a large part of it is just hanging out in the belly, still producing chemicals but not available to hold food. Thus, right off the bat, the amount of food that can be consumed is significantly restricted.

Further, the gastric bypass surgeon attaches this newly created small pouch to the small intestine far enough down the line so that absorption is significantly decreased as well. The new arrangement forms a "Y" and gives the Roux-en-Y its name (Roux was the name of the surgeon who first described the procedure in the 1800's).

In contrast, the sleeve gastrectomy is a purely restrictive procedure. And you may be tipped off by the -ectomy suffix . . . a large portion of the stomach is removed. And that's it. No reversibility, no band that needs to be filled with fluid, no port infections, just a long thin stomach where a football used to be.

Researchers in Greece performed a double-blind prospective study (a reader's favorite terms) with 32 patients, 16 in each surgical group. Measurements of dependent variables were taken at 5 times: preoperatively, and then postoperatively at 1, 3, 6, and 12 months. Of course, both groups lost a significant amount of weight and enjoyed improvements in medical outcomes during that first year.

More interestingly, the patients in the gastric bypass group did not show a significant change in fasting plasma ghrelin levels in the same period. And the patients in the sleeve gastrectomy group did.

A subset of patients were also tested 2 hours after a meal, and ghrelin levels from before and after eating were compared. The patients in the sleeve gastrectomy group showed a decrease of 21.3%, a statistically significant change, and those in the Roux-en-Y group showed a 14% decrease, which was not statistically significant.

So, this study seems to suggest that there is a specific spot or area in the stomach responsible for production of ghrelin, and that sometimes that spot is removed or neutralized with surgery. Again, in bariatric surgery as in real estate, some value may be attributed to location, location, location.



Karamanakos, S., Vagenas, K., Kalfarentzos, F., & Alexandrides, T. (2008). Weight Loss, Appetite Suppression, and Changes in Fasting and Postprandial Ghrelin and Peptide-YY Levels After Roux-en-Y Gastric Bypass and Sleeve Gastrectomy Annals of Surgery, 247 (3), 401-407 DOI: 10.1097/SLA.0b013e318156f012

Is Ghrelin Simply Related to Weight Loss?

In direct contradiction to the results discussed in the last post, Holdstock, et al. found that ghrelin levels do not fall precipitously after gastric bypass. In fact, they concluded that ghrelin responds to weight loss in a predicted manner . . . by increasing.

Holdstock, et al. measured four substances involved in metabolism that we will collectively call gut hormones: ghrelin, adinopectin, insulin and leptin. They compared the levels of these hormones in the blood of their research participants before gastric bypass, 6 months after, and 12 months after. In contrast to Cummings' results, Holdstock found that ghrelin increased only as participants lost weight, which is what we would expect under normal circumstances.

In another part of the study, Holdstock compared ghrelin levels in obese women who had had gastric bypass and those who had not. Perhaps you can anticipate the finding . . . there was no significant difference between the two groups.

As Holdstock concludes: "Apparently, further detailed studies are needed to fully elucidate the effect of gastrointestinal surgery on circulating ghrelin levels" (p. 3180). I know, I know. Just like a scientist to say we need more research. And more research we shall find.

I wonder, could the surgical techniques used in Uppsala, Sweden (Holdstock) differ enough from those used in Seattle, Washington (Cummings) to explain such disparate conclusions? I mean, is there a sweet spot in the stomach where ghrelin is produced, and sometimes it is surgically bypassed and sometimes it is not?


Holdstock, C. (2003). Ghrelin and Adipose Tissue Regulatory Peptides: Effect of Gastric Bypass Surgery in Obese Humans Journal of Clinical Endocrinology & Metabolism, 88 (7), 3177-3183 DOI: 10.1210/jc.2002-021734