Why We Struggle to Maintain Weight Loss

Tara Parker-Pope of The New York Times has written an excellent summary of research on set point theory, that is, the body's tendency to defend a higher weight after weight loss. And some of us may just have to work harder to maintain weight loss because of other genetic factors.

This research can be used as an excuse for weight regain - "What's the use?" or "My genes made me do it" - or as information that can help us forgive ourselves for sometimes falling short of our goals. Of course, I recommend it as a source of compassion, not an excuse for poor eating habits.

Tara Parker-Pope's article

The research also supports the idea that gastric bypass surgery resets the set point that the body will defend going forward. Surgery is not a simple engineering change. Rather, it starts a complex biochemical process that supports weight loss until the new set point is reached.

Does Preoperative Weight Loss Affect LONG-Term Postoperative Weight Loss?

Some surgical weight loss programs require that, in preparation for bariatric surgery, patients lose a certain amount of weight. This might be a fixed amount, such as 25 pounds, a percentage of total body weight, or a percentage of excess body weight. To my knowledge there are no guidelines from the American Society of Metabolic and Bariatric Surgery (ASMBS) in favor of or opposed to this requirement, as it pertains to weight loss. The ASMBS guidelines do recommend presurgical weight loss in order to reduce liver size and thus decrease surgical risk.

In the previous post, we reviewed a study looking at short-term weight loss after Roux-en-Y gastric bypass surgery. Today we will consider a study conducted at a single medical center that recommends that patients lose 10% of their total body weight before surgery. These clinician researchers state that their experience tells them that preoperative weight loss improves weight loss outcome in the long term, and their data support their expectation. However, as we'll see, there are some problems with the study that limit the validity of that claim.

Let's take a look at the results. Some number of patients were recruited for the study and their preoperative weight loss was documented. We are not told how many people initially participated in the study, only that 150 patients were available for follow-up after 3 years and 95 were available after 4 years.

Right off the bat, there is a question. How many people were unavailable after 3 or 4 years, and, more importantly, why? Were there 200 or 500 or 1,000 participants who signed on to the study in the preoperative phase? We don't know, and this means we also don't know why people were unavailable. Did they simply move away? Did they stop coming in for medical care for some other reason relevant to their weight loss? We also cannot consider how - or if - the dropout rate affects the results. Maybe the 150 patients available after 3 years and the 95 available after 4 years had some special characteristics that set them apart from the general population of gastric bypass candidates. We cannot determine this from the article.

The data clearly showed exactly what the researchers expected: a nearly linear, statistically significant correlation between the weight a patient lost before surgery the weight they had lost at 3 and 4 years out. Percentages of both total body weight and excess body weight followed this relationship.

Another problem with the study: no control group. It is a purely correlational study. This wouldn't be a problem if the researchers hadn't used the word "causation." OUCH! Remember from Intro Psych (and many other intro science courses) the 3 requirements for a true experiment: random sampling from the population, random assignment to groups, and the presence of a control group. Based on what is reported in this article, none of these conditions were met.

So, while intuitively it sounds logical that preoperative weight loss will solidify behavioral changes and ultimately influence long-term weight loss, I'm still looking for evidence that this claim can be supported. What is known is that preoperative weight loss has many other benefits for the patient, such as reduced liver size at the time of surgery (reducing the risk of converting a laparoscopic procedure to an open one), shorter operating time, and fewer surgical complications. These factors alone speak to the importance of starting weight loss as early as possible.


Alger-Mayer, S., Polimeni, J., & Malone, M. (2008). Preoperative Weight Loss as a Predictor of Long-term Success Following Roux-en-Y Gastric Bypass. Obesity Surgery, 18 (7), 772-775 DOI: 10.1007/s11695-008-9482-2

Does Preoperative Weight Loss Affect Short-Term Postoperative Weight Loss?

May is "Mental Health Month" and today is "Mental Health Month Blog Party," an initiative of the American Psychological Association's Public Education Campaign. Today, bloggers who write about mental health issues will be linked to on APA's public information web site:

http://www.yourmindyourbody.org/

So, since every bariatric surgery patient is indoctrinated with the message, "Bariatric surgery is a tool, not a panacea, and I know I have to make lifestyle changes to maintain my weight loss," I thought I would blog today about the value - or lack thereof - of losing weight before having surgery. Some bariatric surgery programs encourage, or even require, prospective patients to lose some amount of weight before having their procedure.

After all, doesn't it make good intuitive sense that solidifying some of those important behavioral changes would lead to a better outcome? Researchers at the Stanford School of Medicine asked that question and reported their results in today's article.


Eisenberg, D., Duffy, A., & Bell, R. (2010). Does Preoperative Weight Change Predict Postoperative Weight Loss after Laparoscopic Roux-en-Y Gastric Bypass in the Short Term? Journal of Obesity, 2010, 1-4 DOI: 10.1155/2010/907097


The authors question two basic assumptions in bariatric surgery research and practice - that preoperative weight loss indicates an individual's intrinsic motivation for behavior modification, and that intrinsic motivation is a valid predictor of outcome. Some institutions may deny patients bariatric surgery when those patients do not demonstrate sufficient commitment by losing weight on their own.

The researchers deserve credit for designing a very well-controlled study: all 354 study participants had laparoscopic Roux-en-Y gastric bypass surgery by the same surgeon at a single institution. All preoperative and postoperative care followed the same guidelines. Large surgical centers tend to have dedicated well-trained staff and large patient volumes. They lend themselves to this type of large prospective study.

Of the 354 patients having surgery, 256 were available for evaluation 1 year later and were included in the study. Of these patients, 125 lost weight before surgery, 104 gained weight, and 27 had no change. A statistical analysis did not find a significant correlation between weight lost (or gained) before surgery and weight lost in the first year.

Thus, the authors conclude (correctly, given their assumptions and research question) that preoperative weight loss should not be required prior to Roux-en-Y because preoperative weight change does not affect 1-year outcomes . . . assuming 1-year outcomes are all one is interested in.

But what about longer-term outcomes? It is pretty much a given that the first year post-op will result in significant weight loss. That's not where the problems set in. Continuing to lose weight and maintaining that weight loss after the first 12-24 months is where the challenges lie. And research tells us that long term success requires long-term behavior changes.

So the next question is . . . Does preoperative behavior change affect behavior change and weight loss in the long term, say 3-5 years? In other words, does the intuitive assumption that the sooner one starts behavior change the longer and stronger those new habits are likely to remain? Stay tuned.

And Happy Mental Health Month! 

How do you spell "success" after bariatric surgery?

The sweet smell of "success" . . . it's so intangible, so personal, so dependent on the point of view. Here's a sampling of what I have heard from patients:

"I can buy clothes in a regular department store!"

Often after years of buying shapeless clothes in specialty stores, many people - women and men! - enjoy trying on clothes in a department store, feeling stylish and reveling in colors other than black.

"I don't need a seat belt extender on airplanes anymore! And I actually fit into the seat properly."
Many post-bariatric-surgery patients start flying again after many years of staying at home because of shame at the ordeal of negotiating the seat constraints. Attending far-away family events suddenly becomes possible and taking vacations just for the fun of it becomes part of the normal routine.

"I don't have to wear my CPAP mask anymore!"
CPAP stands for Continuous Positive Airway Pressure and the mask is attached to a machine that pumps air into and out of the nose throughout the night. It is the work-around of choice for a condition known as sleep apnea. Wearing a CPAP mask is nobody's idea of a good time, but waking up refreshed and having energy throughout the day makes the ordeal worthwhile for many people. Obesity is a significant risk factor for sleep apnea, and it often clears up after weight loss. Sleeping without the mask and the machine represents a dramatic improvement in quality of life for many people.

"I'm off all my medications!"

Other conditions that often clear up after weight loss or simply after gastric bypass (see previous posts) include Type 2 diabetes, hypertension, high cholesterol, and psoriasis. Fewer medications means saving money, time and trouble. And individuals may feel a sense of greater autonomy over their own health.

Which brings us to the question of point of view . . . how do researchers define success after bariatric surgery? After all, the outcomes measured for a research study must be quantifiable. And, while there are questionnaires that assess a person's quality of life, today we are going to examine a study that looks at weight loss only.

Specifically, a way of measuring weight loss not in pounds, but expressed as a percentage of the weight an individual needs to lose. For example, if an individual weighs 300 pounds, and the ideal weight is 200 pounds, then 100 pounds is the excess body weight (EBW). If the person has now lost 40 pounds, then the percentage of excess weight that has been lost is 40%.

Snyder, B., Nguyen, A., Scarbourough, T., Yu, S., & Wilson, E. (2009). Comparison of those who succeed in losing significant excessive weight after bariatric surgery and those who fail. Surgical Endoscopy, 23 (10), 2302-2306. DOI: 10.1007/s00464-008-0322-1

In this study, "good weight loss" was defined as >= 50% EBW, and "poor weight loss" as <= 30% EBW within the first year after surgery. They included patients who had had gastric bypass and gastric banding procedures.

There are problems right off the bat. First, these are not generally accepted definitions, and the authors provided no justification for their choices. And, in general, I am always wary of analyses that throw out data. Why not include all the data in a linear analysis rather than creating 2 extreme groups? This question was not addressed.

Second, weight loss in and of itself is not necessarily the best definition of success. Ultimately, it is lifestyle change that allows patients to maintain weight loss.

Third, the most obese patients likely did not have enough time to lose 50% EBW. In other words, we might predict that the "good weight loss" group is going to be disproportionately made up of people who started out with a lower BMI. And this is exactly what was reported in the study for both gastric bypass and banding groups.

And fourth, the timelines for weight loss differ based on the procedure performed, that is, gastric bypass patients generally experience a drastic weight loss in year 1, tapering off to their maximum at the end of 3 years, and gastric banding patients see a more steady curve over those first 3 years. Often the results at the end of 3 years are similar, but that first year looks very different based on the procedure.

Again, this is exactly what was reported. Among bypass patients, 75% achieved "good weight loss" and only 5% had "poor weight loss." Fine, but this represents the period of most dramatic weight loss for this group. Among banding patients, only 27% achieved "good weight loss" and 34% had "poor weight loss." But when the banding patients have time to reach their potential, who knows how this comparison would turn out?

I was hoping to learn some useful distinctions about success and failure from this study, but, alas, that was not to be. Here's what I'll be looking for in the future:

First, a more robust definition of success after bariatric surgery, including %EBW lost, objective improvements in pre-existing medical conditions, and subjective improvements in quality of life.

Second, the inclusion of life style changes in the prediction of success. For example, how do exercise, dietary choices, and adherence to nutrition supplements contribute to long-term weight loss?

Third, the selection of a dataset that allows for meaningful comparisons. For example, the validity of a study comparing bypass and banding patients would be strengthened by using a follow-up period of 3 years.

Gastric bypass and psoriasis????

Hossler EW, Maroon MS, & Mowad CM (2010). Gastric bypass surgery improves psoriasis. Journal of the American Academy of Dermatology PMID: 20655127

How could I not blog this article? What could possibly be the connection between gastric bypass and a skin disease?

The authors - dermatologists - describe two cases of significant long-lasting improvement in psoriasis after weight loss from gastric bypass surgery. They point out that obesity has been thought to be a risk factor for psoriasis, and that the risk increases with body mass index (BMI).

But why? The authors propose three possible mechanisms.

First, chronic low-grade inflammation is associated with both obesity and psoriasis, specifically through tumor necrosis factor (TNF)-alpha. Adipose (fat) tissue can secrete TNF-alpha in anyone, and the adipose tissue of obese individuals produces 2.5 times more TNF-alpha than that of people with a normal BMI. And, according to the authors, TNF-alpha plays a major role in the chronic inflammation found in the plaques of psoriasis. Weight loss can result in a decrease in production of TNF-alpha.

So, what is TNF-alpha? It's a cytokine involved in systemic inflammation. And a cytokine? It's a protein molecule secreted by the glial cells of the nervous system and by numerous cells of the immune system. They are used extensively in communication between cells. Dysregulation of cytokines may be involved in autoimmune diseases. Cytokines are also implicated in chronic inflammation. (And you thought the glial cells were just neuron wannabes!)

Second, the connection may be related to leptin. Leptin is a hormone that plays a key role in regulating satiety and metabolism. Obese people have excessive amounts of leptin circulating in their blood, and that's the problem. If it's circulating in the blood, it's not binding to its receptors and doing its job, that is, increasing the feeling of satiety. It has been hypothesized that obese individuals are resistant to leptin in a similar way that people with Type II diabetes are resistant to insulin.

Studies have also demonstrated that leptin levels are higher in people with psoriasis than in control groups. Further, leptin levels decrease after weight loss. Leptin increases the production of the type of T cells found in psoriasis, and stimulates the production of TNF-alpha.

Third, weight loss may alter bacteria on the skin. Obesity has been associated with an increased risk for bacterial and non-bacterial skin infections. The authors are hopeful that weight loss will become an effective treatment for psoriasis.

I'd like to learn more about inflammation. Cursory MedLine searches show that the word "inflammation" occurs in article titles suggesting a link with cardiovascular disease, cancer, some forms of non-Alzheimer's dementia, obesity, psoriasis, eczema, autoimmune disorders, depression, and schizophrenia. With a rap sheet this long, inflammation might be the new public health enemy #1.

Pushing the Envelope

Another cognitive pitfall that came up at the Brigham talk was pushing the envelope after recovering from bariatric surgery. Immediately following surgery, patients usually follow a liquid diet for a time and then gradually introduce foods back into their diet. Most people can tolerate soft plain foods pretty quickly but may have trouble with dairy, sugar, or other items.

Some patients experience dumping syndrome, an extremely uncomfortable rapid emptying of the stomach contents into the small intestine. Symptoms may include nausea, sweating, fainting, weakness, and diarrhea. Sometimes specific foods can be identified as the causes of dumping syndrome, and other times it is unpredictable. Other times, certain foods simply cannot be tolerated and cause patients to very quickly vomit to get them out of the body.

Now, one might think that if a specific food caused one of these very uncomfortable responses, an individual might be highly motivated to avoid that food in the future. But this is not always the case. The 3 counter-examples I wrote about in the last post apply here too:  job, marriage, kids. We typically don't push the envelope in these 3 areas, as in "I'm going to do the least amount of work I can and see what it takes to get fired."

Pushing the envelope becomes a mindset in competition with the goal of self-care. Instead of a positive, health-promoting mindset like, "I'm going to take the best care of myself that I can," the opposite becomes the default.

A mindset of pushing the envelope might sound like:

"Let's see how much ice cream I can eat without getting sick." (Setting the bar pretty low, right?) 

"I'm going to count the French fries so I know how many I can tolerate." (Really?)

"I can have 2 cigarettes a day." (WHY BOTHER?)

"A naturally thin person eats cookies." (If you have had bariatric surgery, you are not a naturally thin person!)

"I need to see how much I can get away with." (Are you 12?)

Sound familiar? That last bullet point has a decidedly adolescent flair to it, don't you think? I hear that a lot from surgery patients. If you have adopted this mindset, please ask yourself why you feel you must risk mistreating your body and sabotaging your health and your weight loss.

Try becoming aware of these dangerous thoughts. That's the first and often most difficult step in changing them. Perhaps you can jot them down in your journal.

When you become aware of pushing the envelope, see if you can challenge yourself to have another response, one that expresses respect for your body and for the surgical procedure you had. Perhaps one of these:

• "I'm not going to risk getting sick just for the taste of that food."
• "Why would I sabotage all I went through to have this surgery?"
• "I can't control my intake of certain foods and it makes sense to avoid them."
• "If I eat this, I will not have the stomach capacity for the healthful food I must eat."
• "I don't want to risk falling into bad habits again."

Now, I don't mean to say that you will never have a piece of birthday cake again. Far from it. But I do want you to distinguish the occasional mindful indulgence from a way of thinking that seriously jeopardizes your success. Start your day with the mindset of an adult, not an adolescent. You have the capacity for mature decision making. Use those frontal lobes!

All-or-Nothing Thinking

Recently I had the opportunity to address the support group for bariatric surgery patients at the Brigham and Women's Hospital here in Boston. One of the topics we discussed is familiar to many people who have engaged in almost any kind of treatment for obesity: all-or-nothing thinking.

You know what this is. It's the idea that you have to stick to a diet and exercise program perfectly, daily, and indefinitely, starting on a Monday, or else you are a failure and might as well shove any old junk into your mouth and live on the sofa. I have been making the point to patients for years that this is the only area of life in which we think this way!

Let's take a look at a few examples of important parts of our lives and test this idea. First, your job. Give this a reality test:  "Starting Monday, I'm going to arrive on time, finish all the tasks on my to-do list, return all phone calls within 24 hours, be prepared for every meeting, and smile while doing it all! And I'm going to do this every day for the rest of my career!" And then, on Tuesday, you arrive 5 minutes late for work:  "Well, that's it! I'm going to the beach and I'll come back when I'm ready to re-commit!"

Next, consider your marriage. Is this you? "I'm going to be the best spouse on the planet! Starting Monday, I'm going to put my spouse's needs first, tell my spouse how wonderful he/she is, prepare his/her favorite meals, and have sex every night! Forever!" Then on Tuesday, when you argue over whose turn it is to take out the trash:  "Enough! I tried to be the perfect spouse! I knew it wouldn't work! I'm outta here and I'll come back when I'm ready to be the perfect spouse again!"

One more example and I think I will demonstrate my point. Let's talk about your kids. Is this you? Careful how you answer! "Starting Monday, I'm going to be the perfect parent. I'm not going to lose it when my kids misbehave, I'm going to help them with their homework, drive them to school, soothe the baby when she cries, and never ever complain. Every day and every night!" Then on Tuesday when the baby simply can't be soothed and you feel frustrated and defeated:  "That's it! You kids are on your own! I'm going away and I'll come back when I can be the perfect parent again!"

I'm betting you could not identify with these examples. So perhaps it's worth reconsidering the all-or-nothing approach to eating and exercise. Remember:

• You don't have to wait until Monday to make a self-respecting choice.
• Every moment is an opportunity to choose health.
• The steps you take create the path of your life.
• Everything you do matters. What you do is a demonstration of who you are.

Have a mindful day!